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  • Parallel LINQ - PLINQ

    - by nmarun
    Turns out now with .net 4.0 we can run a query like a multi-threaded application. Say you want to query a collection of objects and return only those that meet certain conditions. Until now, we basically had one ‘control’ that iterated over all the objects in the collection, checked the condition on each object and returned if it passed. We obviously agree that if we can ‘break’ this task into smaller ones, assign each task to a different ‘control’ and ask all the controls to do their job - in-parallel, the time taken the finish the entire task will be much lower. Welcome to PLINQ. Let’s take some examples. I have the following method that uses our good ol’ LINQ. 1: private static void Linq(int lowerLimit, int upperLimit) 2: { 3: // populate an array with int values from lowerLimit to the upperLimit 4: var source = Enumerable.Range(lowerLimit, upperLimit); 5:  6: // Start a timer 7: Stopwatch stopwatch = new Stopwatch(); 8: stopwatch.Start(); 9:  10: // set the expectation => build the expression tree 11: var evenNumbers =   from num in source 12: where IsDivisibleBy(num, 2) 13: select num; 14: 15: // iterate over and print the returned items 16: foreach (var number in evenNumbers) 17: { 18: Console.WriteLine(string.Format("** {0}", number)); 19: } 20:  21: stopwatch.Stop(); 22:  23: // check the metrics 24: Console.WriteLine(String.Format("Elapsed {0}ms", stopwatch.ElapsedMilliseconds)); 25: } I’ve added comments for the major steps, but the only thing I want to talk about here is the IsDivisibleBy() method. I know I could have just included the logic directly in the where clause. I called a method to add ‘delay’ to the execution of the query - to simulate a loooooooooong operation (will be easier to compare the results). 1: private static bool IsDivisibleBy(int number, int divisor) 2: { 3: // iterate over some database query 4: // to add time to the execution of this method; 5: // the TableB has around 10 records 6: for (int i = 0; i < 10; i++) 7: { 8: DataClasses1DataContext dataContext = new DataClasses1DataContext(); 9: var query = from b in dataContext.TableBs select b; 10: 11: foreach (var row in query) 12: { 13: // Do NOTHING (wish my job was like this) 14: } 15: } 16:  17: return number % divisor == 0; 18: } Now, let’s look at how to modify this to PLINQ. 1: private static void Plinq(int lowerLimit, int upperLimit) 2: { 3: // populate an array with int values from lowerLimit to the upperLimit 4: var source = Enumerable.Range(lowerLimit, upperLimit); 5:  6: // Start a timer 7: Stopwatch stopwatch = new Stopwatch(); 8: stopwatch.Start(); 9:  10: // set the expectation => build the expression tree 11: var evenNumbers = from num in source.AsParallel() 12: where IsDivisibleBy(num, 2) 13: select num; 14:  15: // iterate over and print the returned items 16: foreach (var number in evenNumbers) 17: { 18: Console.WriteLine(string.Format("** {0}", number)); 19: } 20:  21: stopwatch.Stop(); 22:  23: // check the metrics 24: Console.WriteLine(String.Format("Elapsed {0}ms", stopwatch.ElapsedMilliseconds)); 25: } That’s it, this is now in PLINQ format. Oh and if you haven’t found the difference, look line 11 a little more closely. You’ll see an extension method ‘AsParallel()’ added to the ‘source’ variable. Couldn’t be more simpler right? So this is going to improve the performance for us. Let’s test it. So in my Main method of the Console application that I’m working on, I make a call to both. 1: static void Main(string[] args) 2: { 3: // set lower and upper limits 4: int lowerLimit = 1; 5: int upperLimit = 20; 6: // call the methods 7: Console.WriteLine("Calling Linq() method"); 8: Linq(lowerLimit, upperLimit); 9: 10: Console.WriteLine(); 11: Console.WriteLine("Calling Plinq() method"); 12: Plinq(lowerLimit, upperLimit); 13:  14: Console.ReadLine(); // just so I get enough time to read the output 15: } YMMV, but here are the results that I got:    It’s quite obvious from the above results that the Plinq() method is taking considerably less time than the Linq() version. I’m sure you’ve already noticed that the output of the Plinq() method is not in order. That’s because, each of the ‘control’s we sent to fetch the results, reported with values as and when they obtained them. This is something about parallel LINQ that one needs to remember – the collection cannot be guaranteed to be undisturbed. This could be counted as a negative about PLINQ (emphasize ‘could’). Nevertheless, if we want the collection to be sorted, we can use a SortedSet (.net 4.0) or build our own custom ‘sorter’. Either way we go, there’s a good chance we’ll end up with a better performance using PLINQ. And there’s another negative of PLINQ (depending on how you see it). This is regarding the CPU cycles. See the usage for Linq() method (used ResourceMonitor): I have dual CPU’s and see the height of the peak in the bottom two blocks and now compare to what happens when I run the Plinq() method. The difference is obvious. Higher usage, but for a shorter duration (width of the peak). Both these points make sense in both cases. Linq() runs for a longer time, but uses less resources whereas Plinq() runs for a shorter time and consumes more resources. Even after knowing all these, I’m still inclined towards PLINQ. PLINQ rocks! (no hard feelings LINQ)

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  • Building KPIs to monitor your business Its not really about the Technology

    When I have discussions with people about Business Intelligence, one of the questions the inevitably come up is about building KPIs and how to accomplish that. From a technical level the concept of a KPI is very simple, almost too simple in that it is like the tip of an iceberg floating above the water. The key to that iceberg is not really the tip, but the mass of the iceberg that is hidden beneath the surface upon which the tip sits. The analogy of the iceberg is not meant to indicate that the foundation of the KPI is overly difficult or complex. The disparity in size in meant to indicate that the larger thing that needs to be defined is not the technical tip, but the underlying business definition of what the KPI means. From a technical perspective the KPI consists of primarily the following items: Actual Value This is the actual value data point that is being measured. An example would be something like the amount of sales. Target Value This is the target goal for the KPI. This is a number that can be measured against Actual Value. An example would be $10,000 in monthly sales. Target Indicator Range This is the definition of ranges that define what type of indicator the user will see comparing the Actual Value to the Target Value. Most often this is defined by stoplight, but can be any indicator that is going to show a status in a quick fashion to the user. Typically this would be something like: Red Light = Actual Value more than 5% below target; Yellow Light = Within 5% of target either direction; Green Light = More than 5% higher than Target Value Status\Trend Indicator This is an optional attribute of a KPI that is typically used to show some kind of trend. The vast majority of these indicators are used to show some type of progress against a previous period. As an example, the status indicator might be used to show how the monthly sales compare to last month. With this type of indicator there needs to be not only a definition of what the ranges are for your status indictor, but then also what value the number needs to be compared against. So now we have an idea of what data points a KPI consists of from a technical perspective lets talk a bit about tools. As you can see technically there is not a whole lot to them and the choice of technology is not as important as the definition of the KPIs, which we will get to in a minute. There are many different types of tools in the Microsoft BI stack that you can use to expose your KPI to the business. These include Performance Point, SharePoint, Excel, and SQL Reporting Services. There are pluses and minuses to each technology and the right technology is based a lot on your goals and how you want to deliver the information to the users. Additionally, there are other non-Microsoft tools that can be used to expose KPI indicators to your business users. Regardless of the technology used as your front end, the heavy lifting of KPI is in the business definition of the values and benchmarks for that KPI. The discussion about KPIs is very dependent on the history of an organization and how much they are exposed to the attributes of a KPI. Often times when discussing KPIs with a business contact who has not been exposed to KPIs the discussion tends to also be a session educating the business user about what a KPI is and what goes into the definition of a KPI. The majority of times the business user has an idea of what their actual values are and they have been tracking those numbers for some time, generally in Excel and all manually. So they will know the amount of sales last month along with sales two years ago in the same month. Where the conversation tends to get stuck is when you start discussing what the target value should be. The actual value is answering the What and How much questions. When you are talking about the Target values you are asking the question Is this number good or bad. Typically, the user will know whether or not the value is good or bad, but most of the time they are not able to quantify what is good or bad. Their response is usually something like I just know. Because they have been watching the sales quantity for years now, they can tell you that a 5% decrease in sales this month might actually be a good thing, maybe because the salespeople are all waiting until next month when the new versions come out. It can sometimes be very hard to break the business people of this habit. One of the fears generally is that the status indicator is not subjective. Thus, in the scenario above, the business user is going to be fearful that their boss, just looking at a negative red indicator, is going to haul them out to the woodshed for a bad month. But, on the flip side, if all you are displaying is the amount of sales, only a person with knowledge of last month sales and the target amount for this month would have any idea if $10,000 in sales is good or not. Here is where a key point about KPIs needs to be communicated to both the business user and any user who might be viewing the results of that KPI. The KPI is just one tool that is used to report on business performance. The KPI is meant as a quick indicator of one business statistic. It is not meant to tell the entire story. It does not answer the question Why. Its primary purpose is to objectively and quickly expose an area of the business that might warrant more review. There is always going to be the need to do further analysis on any potential negative or neutral KPI. So, hopefully, once you have convinced your business user to come up with some target numbers and ranges for status indicators, you then need to take the next step and help them answer the Why question. The main question here to ask is, Okay, you see the indicator and you need to discover why the number is what is, where do you go?. The answer is usually a combination of sources. A sales manager might have some of the following items at their disposal (Marketing report showing a decrease in the promotional discounts for the month, Pricing Report showing the reduction of prices of older models, an Inventory Report showing the discontinuation of a particular product line, or a memo showing the ending of a large affiliate partnership. The answers to the question Why are never as simple as a single indicator value. Bring able to quickly get to this information is all about designing how a user accesses the KPIs and then also how easily they can get to the additional information they need. This is where a Dashboard mentality can come in handy. For example, the business user can have a dashboard that shows their KPIs, but also has links to some of the common reports that they run regarding Sales Data. The users boss may have the same KPIs on their dashboard, but instead of links to individual reports they are going to have a link to a status report that was created by the user that pulls together all the data about the KPI in a summary format the users boss can review. So some of the key things to think about when building or evaluating KPIs for your organization: Technology should not be the driving factor KPIs are of little value without some indicator for whether a value is good, bad or neutral. KPIs only give an answer to the Is this number good\bad? question Make sure the ability to drill into the Why of a KPI is close at hand and relevant to the user who is viewing the KPI. The KPI is a key business tool when defined properly to help monitor business performance across the enterprise in an objective and consistent manner. At times it might feel like the process of defining the business aspects of a KPI can sometimes be arduous, the payoff in the end can far outweigh the costs. Some of the benefits of going through this process are a better understanding of the key metrics for an organization and the measure of those metrics and a consistent snapshot of business performance that can be utilized across the organization. And I think that these are benefits to any organization regardless of the technology or the implementation.Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • Windows 8 Launch&ndash;Why OEM and Retailers Should STFU

    - by D'Arcy Lussier
    Microsoft has gotten a lot of flack for the Surface from OEM/hardware partners who create Windows-based devices and I’m sure, to an extent, retailers who normally stock and sell Windows-based devices. I mean we all know how this is supposed to work – Microsoft makes the OS, partners make the hardware, retailers sell the hardware. Now Microsoft is breaking the rules by not only offering their own hardware but selling them via online and through their Microsoft branded stores! The thought has been that Microsoft is trying to set a standard for the other hardware companies to reach for. Maybe. I hope, at some level, Microsoft may be covertly responding to frustrations associated with trusting the OEMs and Retailers to deliver on their part of the supply chain. I know as a consumer, I’m very frustrated with the Windows 8 launch. Aside from the Surface sales, there’s nothing happening at the retail level. Let me back up and explain. Over the weekend I visited a number of stores in hopes of trying out various Windows 8 devices. Out of three retailers (Staples, Best Buy, and Future Shop), not *one* met my expectations. Let me be honest with you Staples, I never really have high expectations from your computer department. If I need paper or pens, whatever, but computers – you’re not the top of my list for price or selection. Still, considering you flaunted Win 8 devices in your flyer I expected *something* – some sign of effort that you took the Windows 8 launch seriously. As I entered the 1910 Pembina Highway location in Winnipeg, there was nothing – no signage, no banners – nothing that would suggest Windows 8 had even launched. I made my way to the laptops. I had to play with each machine to determine which ones were running Windows 8. There wasn’t anything on the placards that made it obvious which were Windows 8 machines and which ones were Windows 7. Likewise, there was no easy way to identify the touch screen laptop (the HP model) from the others without physically touching the screen to verify. Horrible experience. In the same mall as the Staples I mentioned above, there’s a Future Shop. Surely they would be more on the ball. I walked in to the 1910 Pembina Highway location and immediately realized I would not get a better experience. Except for the sign by the front door mentioning Windows 8, there was *nothing* in the computer department pointing you to the Windows 8 devices. Like in Staples, the Win 8 laptops were mixed in with the Win 7 ones and there was nothing notable calling out which ones were running Win 8. I happened to hit up the St. James Street location today, thinking since its a busier store they must have more options. To their credit, they did have two staff members decked out in Windows 8 shirts and who were helping a customer understand Windows 8. But otherwise, there was nothing highlighting the Windows 8 devices and they were again mixed in with the rest of the Win 7 machines. Finally, we have the St. James Street Best Buy location here in Winnipeg. I’m sure Best Buy will have their act together. Nope, not even close. Same story as the others: minimal signage (there was a sign as you walked in with a link to this schedule of demo days), Windows 8 hardware mixed with the rest of the PC offerings, and no visible call-outs identifying which were Win 8 based. This meant that, like Future Shop and Staples, if you wanted to know which machine had Windows 8 you had to go and scrutinize each machine. Also, there was nothing identifying which ones were touch based and which were not. Just Another Day… To these retailers, it seemed that the Windows 8 launch was just another day, with another product to add to the showroom floor. Meanwhile, Apple has their dedicated areas *in all three stores*. It was dead simple to find where the Apple products were compared to the Windows 8 products. No wonder Microsoft is starting to push their own retail stores. No wonder Microsoft is trying to funnel orders through them instead of relying on these bloated retail big box stores who obviously can’t manage a product launch. It’s Not Just The Retailers… Remember when the Acer CEO, Founder, and President of Computer Global Operations all weighed in on how Microsoft releasing the Surface would have a “huge negative impact for the ecosystem and other brands may take a negative reaction”? Also remember the CEO stating “[making hardware] is not something you are good at so please think twice”? Well the launch day has come and gone, and so far Microsoft is the only one that delivered on having hardware available on the October 26th date. Oh sure, there are laptops running Windows 8 – but all in one desktop PCs? I’ve only seen one or two! And tablets are *non existent*, with some showing an early to late November availability on Best Buy’s website! So while the retailers could be doing more to make it easier to find Windows 8 devices, the manufacturers could help by *getting devices into stores*! That’s supposedly something that these companies are good at, according to the Acer CEO. So Here’s What the Retailers and Manufacturers Need To Do… Get Product Out The pivotal timeframe will be now to the end of November. We need to start seeing all these fantastic pieces of hardware ship – including the Samsung ATIV Smart PC Pro, the Acer Iconia, the Asus TAICHI 21, and the sexy Samsung Series 7 27” desktop. It’s not enough to see product announcements, we need to see actual devices. Make It Easy For Customers To Find Win8 Devices You want to make it easy to sell these things? Make it easy for people to find them! Have staff on hand that really know how these devices run and what can be done with them. Don’t just have a single demo day, have people who can demo it every day! Make It Easy to See the Features There’s touch screen desktops, touch screen laptops, tablets, non-touch laptops, etc. People need to easily find the features for each machine. If I’m looking for a touch-laptop, I shouldn’t need to sift through all the non-touch laptops to find them – at the least, I need to quickly be able to see which ones are touch. I feel silly even typing this because this should be retail 101 and I have no retail background (but I do have an extensive background as a customer). In Summary… Microsoft launching the Surface and selling them through their own channels isn’t slapping its OEM and retail partners in the face; its slapping them to wake the hell up and stop coasting through Windows launch events like they don’t matter. Unless I see some improvements from vendors and retailers in November, I may just hold onto my money for a Surface Pro even if I have to wait until early 2013. Your move OEM/Retailers. *Update – While my experience has been in Winnipeg, similar experiences have been voiced from colleagues in Calgary and Edmonton.

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  • Expectations + Rewards = Innovation

    - by D'Arcy Lussier
    “Innovation” is a heavy word. We regard those that embrace it as “Innovators”. We describe organizations as being “Innovative”. We hold those associated with the word in high regard, even though its dictionary definition is very simple: Introducing something new. What our culture has done is wrapped Innovation in white robes and a gold crown. Innovation is rarely just introducing something new. Innovations and innovators are typically associated with other terms: groundbreaking, genius, industry-changing, creative, leading. Being a true innovator and creating innovations are a big deal, and something companies try to strive for…or at least say they strive for. There’s huge value in being recognized as an innovator in an industry, since the idea is that innovation equates to increased profitability. IBM ran an ad a few years back that showed what their view of innovation is: “The point of innovation is to make actual money.” If the money aspect makes you feel uneasy, consider it another way: the point of innovation is to <insert payoff here>. Companies that innovate will be more successful. Non-profits that innovate can better serve their target clients. Governments that innovate can better provide services to their citizens. True innovation is not easy to come by though. As with anything in business, how well an organization will innovate is reliant on the employees it retains, the expectations placed on those employees, and the rewards available to them. In a previous blog post I talked about one formula: Right Employees + Happy Employees = Productive Employees I want to introduce a new one, that builds upon the previous one: Expectations + Rewards = Innovation  The level of innovation your organization will realize is directly associated with the expectations you place on your staff and the rewards you make available to them. Expectations We may feel uncomfortable with the idea of placing expectations on our staff, mainly because expectation has somewhat of a negative or cold connotation to it: “I expect you to act this way or else!” The problem is in the or-else part…we focus on the negative aspects of failing to meet expectations instead of looking at the positive side. “I expect you to act this way because it will produce <insert benefit here>”. Expectations should not be set to punish but instead be set to ensure quality. At a recent conference I spoke with some Microsoft employees who told me that you have five years from starting with the company to reach a “Senior” level. If you don’t, then you’re let go. The expectation Microsoft placed on their staff is that they should be working towards improving themselves, taking more responsibility, and thus ensure that there is a constant level of quality in the workforce. Rewards Let me be clear: a paycheck is not a reward. A paycheck is simply the employer’s responsibility in the employee/employer relationship. A paycheck will never be the key motivator to drive innovation. Offering employees something over and above their required compensation can spur them to greater performance and achievement. Working in the food service industry, this tactic was used again and again: whoever has the highest sales over lunch will receive a free lunch/gift certificate/entry into a draw/etc. There was something to strive for, to try beyond the baseline of what our serving jobs were. It was through this that innovative sales techniques would be tried and honed, with key servers being top sellers time and time again. At a code camp I spoke at, I was amazed to see that all the employees from one company receive $100 Visa gift cards as a thank you for taking time to speak. Again, offering something over and above that can give that extra push for employees. Rewards work. But what about the fairness angle? In the restaurant example I gave, there were servers that would never win the competition. They just weren’t good enough at selling and never seemed to get better. So should those that did work at performing better and produce more sales for the restaurant not get rewarded because those who weren’t working at performing better might get upset? Of course not! Organizations succeed because of their top performers and those that strive to join their ranks. The Expectation/Reward Graph While the Expectations + Rewards = Innovation formula may seem like a simple mathematics formula, there’s much more going under the hood. In fact there are three different outcomes that could occur based on what you put in as values for Expectations and Rewards. Consider the graph below and the descriptions that follow: Disgruntled – High Expectation, Low Reward I worked at a company where the mantra was “Company First, Because We Pay You”. Even today I still hear stories of how this sentiment continues to be perpetuated: They provide you a paycheck and a means to live, therefore you should always put them as your top priority. Of course, this is a huge imbalance in the expectation/reward equation. Why would anyone willingly meet high expectations of availability, workload, deadlines, etc. when there is no reward other than a paycheck to show for it? Remember: paychecks are not rewards! Instead, you see employees be disgruntled which not only affects the level of production but also the level of quality within an organization. It also means that you see higher turnover. Complacent – Low Expectation, Low Reward Complacency is a systemic problem that typically exists throughout all levels of an organization. With no real expectations or rewards, nobody needs to excel. In fact, those that do try to innovate, improve, or introduce new things into the organization might be shunned or pushed out by the rest of the staff who are just doing things the same way they’ve always done it. The bigger issue for the organization with low/low values is that at best they’ll never grow beyond their current size (and may shrink actually), and at worst will cease to exist. Entitled – Low Expectation, High Reward It’s one thing to say you have the best people and reward them as such, but its another thing to actually have the best people and reward them as such. Organizations with Entitled employees are the former: their organization provides them with all types of comforts, benefits, and perks. But there’s no requirement before the rewards are dolled out, and there’s no short-list of who receives the rewards. Everyone in the company is treated the same and is given equal share of the spoils. Entitlement is actually almost identical with Complacency with one notable difference: just try to introduce higher expectations into an entitled organization! Entitled employees have been spoiled for so long that they can’t fathom having rewards taken from them, or having to achieve specific levels of performance before attaining them. Those running the organization also buy in to the Entitled sentiment, feeling that they must persist the same level of comforts to appease their staff…even though the quality of the employee pool may be suspect. Innovative – High Expectation, High Reward Finally we have the Innovative organization which places high expectations but also provides high rewards. This organization gets it: if you truly want the best employees you need to apply equal doses of pressure and praise. Realize that I’m not suggesting crazy overtime or un-realistic working conditions. I do not agree with the “Glengary-Glenross” method of encouragement. But as anyone who follows sports can tell you, the teams that win are the ones where the coaches push their players to be their best; to achieve new levels of performance that they didn’t know they could receive. And the result for the players is more money, fame, and opportunity. It’s in this environment that organizations can focus on innovation – true innovation that builds the business and allows everyone involved to truly benefit. In Closing Organizations love to use the word “Innovation” and its derivatives, but very few actually do innovate. For many, the term has just become another marketing buzzword to lump in with all the other business terms that get overused. But for those organizations that truly get the value of innovation, they will be the ones surging forward while other companies simply fade into the background. And they will be the organizations that expect more from their employees, and give them their just rewards.

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  • codingBat repeatEnd using regex

    - by polygenelubricants
    I'm trying to understand regex as much as I can, so I came up with this regex-based solution to codingbat.com repeatEnd: Given a string and an int N, return a string made of N repetitions of the last N characters of the string. You may assume that N is between 0 and the length of the string, inclusive. public String repeatEnd(String str, int N) { return str.replaceAll( ".(?!.{N})(?=.*(?<=(.{N})))|." .replace("N", Integer.toString(N)), "$1" ); } Explanation on its parts: .(?!.{N}): asserts that the matched character is one of the last N characters, by making sure that there aren't N characters following it. (?=.*(?<=(.{N}))): in which case, use lookforward to first go all the way to the end of the string, then a nested lookbehind to capture the last N characters into \1. Note that this assertion will always be true. |.: if the first assertion failed (i.e. there are at least N characters ahead) then match the character anyway; \1 would be empty. In either case, a character is always matched; replace it with \1. My questions are: Is this technique of nested assertions valid? (i.e. looking behind during a lookahead?) Is there a simpler regex-based solution?

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  • codingbat wordEnds using regex

    - by polygenelubricants
    I'm trying to solve wordEnds from codingbat.com using regex. This is the simplest as I can make it with my current knowledge of regex: public String wordEnds(String str, String word) { return str.replaceAll( String.format( ".*?(?=%s)(?<=(.|^))%1$s(?=(.|$))|.+", java.util.regex.Pattern.quote(word) ), "$1$2" ); } String.format is used to inject word into the pattern for both readability and convenience (it's injected twice). Pattern.quote isn't necessary to pass their tests, but I think it's required for a proper regex-based solution. The regex has two major parts: If after matching as few characters as possible ".*?", word can still be found "(?=%s)", then lookbehind to capture any character immediately preceding it "(?<=(.|^))", match word "%1$s" and lookforward to capture any character following it "(?=(.|$))". The initial "if" test ensures that the atomic lookbehind captures only if there's a word Using lookahead to capture the following character doesn't consume it, so it can be used as part of further matching Otherwise match what's left "|.+" Groups 1 and 2 would capture empty strings I think this works in all cases, but it's obviously quite complex. I'm just wondering if others can suggest a simpler regex to do this. Note: I'm not looking for a solution using indexOf and a loop. I want a regex-based replaceAll solution. I also need a working solution that I can just copy-paste into codingbat and passes.

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  • Bubble Breaker Game Solver better than greedy?

    - by Gregory
    For a mental exercise I decided to try and solve the bubble breaker game found on many cell phones as well as an example here:Bubble Break Game The random (N,M,C) board consists N rows x M columns with C colors The goal is to get the highest score by picking the sequence of bubble groups that ultimately leads to the highest score A bubble group is 2 or more bubbles of the same color that are adjacent to each other in either x or y direction. Diagonals do not count When a group is picked, the bubbles disappear, any holes are filled with bubbles from above first, ie shift down, then any holes are filled by shifting right A bubble group score = n * (n - 1) where n is the number of bubbles in the bubble group The first algorithm is a simple exhaustive recursive algorithm which explores going through the board row by row and column by column picking bubble groups. Once the bubble group is picked, we create a new board and try to solve that board, recursively descending down Some of the ideas I am using include normalized memoization. Once a board is solved we store the board and the best score in a memoization table. I create a prototype in python which shows a (2,15,5) board takes 8859 boards to solve in about 3 seconds. A (3,15,5) board takes 12,384,726 boards in 50 minutes on a server. The solver rate is ~3k-4k boards/sec and gradually decreases as the memoization search takes longer. Memoization table grows to 5,692,482 boards, and hits 6,713,566 times. What other approaches could yield high scores besides the exhaustive search? I don't seen any obvious way to divide and conquer. But trending towards larger and larger bubbles groups seems to be one approach Thanks to David Locke for posting the paper link which talks above a window solver which uses a constant-depth lookahead heuristic.

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  • shell scripting: search/replace & check file exist

    - by johndashen
    I have a perl script (or any executable) E which will take a file foo.xml and write a file foo.txt. I use a Beowulf cluster to run E for a large number of XML files, but I'd like to write a simple job server script in shell (bash) which doesn't overwrite existing txt files. I'm currently doing something like #!/bin/sh PATTERN="[A-Z]*0[1-2][a-j]"; # this matches foo in all cases todo=`ls *.xml | grep $PATTERN -o`; isdone=`ls *.txt | grep $PATTERN -o`; whatsleft=todo - isdone; # what's the unix magic? #tack on the .xml prefix with sed or something #and then call the job server; jobserve E "$whatsleft"; and then I don't know how to get the difference between $todo and $isdone. I'd prefer using sort/uniq to something like a for loop with grep inside, but I'm not sure how to do it (pipes? temporary files?) As a bonus question, is there a way to do lookahead search in bash grep? To clarify: so the simplest way to do what i'm asking is (in pseudocode) for i in `/bin/ls *.xml` do replace xml suffix with txt if [that file exists] add to whatsleft list end done

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  • How do I extract a postcode from one column in SSIS using regular expression

    - by Aphillippe
    I'm trying to use a custom regex clean transformation (information found here ) to extract a post code from a mixed address column (Address3) and move it to a new column (Post Code) Example of incoming data: Address3: "London W12 9LZ" Incoming data could be any combination of place names with a post code at the start, middle or end (or not at all). Desired outcome: Address3: "London" Post Code: "W12 9LZ" Essentially, in plain english, "move (not copy) any post code found from address3 into Post Code". My regex skills aren't brilliant but I've managed to get as far as extracting the post code and getting it into its own column using the following regex, matching from Address3 and replacing into Post Code: Match Expression: (?<stringOUT>([A-PR-UWYZa-pr-uwyz]([0-9]{1,2}|([A-HK-Ya-hk-y][0-9]|[A-HK-Ya-hk-y][0-9] ([0-9]|[ABEHMNPRV-Yabehmnprv-y]))|[0-9][A-HJKS-UWa-hjks-uw])\ {0,1}[0-9][ABD-HJLNP-UW-Zabd-hjlnp-uw-z]{2}|([Gg][Ii][Rr]\ 0[Aa][Aa])|([Ss][Aa][Nn]\ {0,1}[Tt][Aa]1)|([Bb][Ff][Pp][Oo]\ {0,1}([Cc]\/[Oo]\ )?[0-9]{1,4})|(([Aa][Ss][Cc][Nn]|[Bb][Bb][Nn][Dd]|[BFSbfs][Ii][Qq][Qq]|[Pp][Cc][Rr][Nn]|[Ss][Tt][Hh][Ll]|[Tt][Dd][Cc][Uu]|[Tt][Kk][Cc][Aa])\ {0,1}1[Zz][Zz]))) Replace Expression: ${stringOUT} So this leaves me with: Address3: "London W12 9LZ" Post Code: "W12 9LZ" My next thought is to keep the above match/replace, then add another to match anything that doesn't match the above regex. I think it might be a negative lookahead but I can't seem to make it work. I'm using SSIS 2008 R2 and I think the regex clean transformation uses .net regex implementation. Thanks.

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  • Having an issue with overwriting an element of a file correctly (numeric)

    - by IngeniousHax
    This is an ATM style program, but currently it doesn't do exactly what I need it to do... I need to get the current balance, and when money is transferred from either checking or savings, it should add it to checking and subtract it from savings. which is does, but not correctly... Input example -=[ Funds Transfer ]=- -=[ Savings to Checking ]=- Account Name: nomadic Amount to transfer: $400 New Balance in Checking: $900 // original was 500 New Balance in Savings: $7.7068e+012 // this should now be 1100... Here is my code, it's a lot of code, but there are no errors, so throwing it into an IDE and compiling should be fairly quick for whoever would like to help. mainBankClass.h mainBankClass.h #ifndef MAINBANKCLASS_H #define MAINBANKCLASS_H #include <iostream> #include <fstream> #include <string> using namespace std; class Banking { protected: string checkAcctName, saveAcctName; // Name on the account int acctNumber[13]; // Account number float acctBalance, initSaveDeposit, initCheckDeposit, depAmt; // amount in account, and amount to deposit public: char getBalanceChoice(); // Get name on account for displaying relevant information char newAccountMenu(); // Create a new account and assign it a random account number void invalid(char *); // If an invalid option is chosen char menu(); // Print the main menu for the user. virtual float deposit(){ return 0; } // virtual function for deposits // virtual float withdrawal() = 0; // Virtual function for withdrawals void fatal(char *); // Handles fatal errors. Banking(); }; class Checking : public Banking { public: friend ostream operator<<(ostream &, Checking &); friend istream operator>>(istream &, Checking &); Checking operator <= (const Checking &) const; void newCheckingAccount(); void viewCheckingBalance(); void transferFromSaving(); float deposit() { return (acctBalance += depAmt); } }; class Saving : public Banking { public: friend ostream &operator<<(ostream &, Saving &); friend istream &operator>>(istream &, Saving &); Saving operator <= (const Saving &) const; void newSavingAccount(); void viewSavingBalance(); void transferFromChecking(); float deposit() { return (acctBalance += depAmt); } }; class checkAndSave : public Banking { public: void newCheckAndSave(); void viewBothBalances(); }; #endif bankAccount.cpp #include <iostream> #include <sstream> #include <string> #include <iomanip> #include <fstream> #include <time.h> #include "MainBankClass.h" /*****************************\ | BANKING CONSTRUCTOR | \*****************************/ Banking::Banking() { string acctName; // Name on the account acctNumber[13] = 0; // Account number acctBalance = 0; initCheckDeposit = 0; initSaveDeposit = 0; depAmt = 0; }; /********************************\ | The following code is to print the menu | | and recieve the users choice on what | | they want to do with the ATM | \********************************/ char Banking::menu() { char choice; system("cls"); cout << "\t\t -=[ Main Menu ]=- \n\n" << "\tA) Create New Account\n" << "\tB) View Account Balance\n" << "\tC) Transfer Funds From Checking To Savings\n" << "\tD) Transfer Funds From Savings To Checking\n" << "\tE) Exit\n" << "\n\n\tSelection: "; cin >> choice; cin.ignore(); choice = toupper(choice); while(!isalpha(choice)) { invalid("[!!] Invalid selection.\n[!!] Choose a valid option: "); cin >> choice; cin.ignore(); } return choice; } /*********************\ | Will read in account choic | | and display it for the user | \*********************/ char Banking::getBalanceChoice() { char choice; fstream saveFile("saving.dat", ios::in | ios::beg); system("cls"); cout << "\t\t -=[ View Account Balance ]=-\n\n"; cout << "A) View Checking Account\n" << "B) View Saving Account\n" << "C) View Checking \\ Saving Account\n" << endl; cout << "Choice: "; cin >> choice; choice = toupper(choice); if(!isalpha(choice)) fatal(" [!!] Invalid Choice"); return choice; } /***************************\ | Incase an invalid decision to made | | this throws the error message sent | | to it by the calling area | \***************************/ void Banking::invalid(char *msg) { cout << msg; } /*************************\ | Used if files can not be opened | | and exits with code 251: | | miscommunication with server | \*************************/ void Banking::fatal(char *msg) { cout << msg; exit(1); } /***************************\ | Create an account, either checking | | or savings, or both. | | Must should create a randomly | | generated account number that will | | correspond with each account. | \***************************/ /************************\ NOTE:: WILL BE UPDATED TO CONTAIN A PIN FOR ACCOUNT VERIFICATION *************************/ char Banking::newAccountMenu() { srand(time(NULL)); // Seed random generator with time initialized to NULL char acctChoice; // choice for the account type ofstream checkFile("checking.dat", ios::out | ios::app); // For saving checking accounts ofstream saveFile("saving.dat", ios::out | ios::app); // For saving savings accounts system("cls"); cout << "\t\t-=[ New Account Creation ]=-\n\n" << endl; cout << "A) Checking Account\n" << "B) Savings Account\n" << "C) Checking and Saving Account\n" << endl; cout << "New account type: "; cin >> acctChoice; acctChoice = toupper(acctChoice); cin.clear(); cin.sync(); return acctChoice; } /********************************************************************* ********************************************************************** CHECKING ACCOUNT CODE ********************************************************************** **********************************************************************/ // New Checking Account Creation void Checking::newCheckingAccount() { system("cls"); ofstream checkFile("checking.dat", ios::out | ios::app); // For saving checking accounts cout << "\t\t -=[ New Checking Account ]=- \n" << endl; cout << "Name of the main holder to be on the account: "; getline(cin, checkAcctName); cout << "Initial deposit amount: $"; cin >> initCheckDeposit; if(initCheckDeposit <= 0) { while(initCheckDeposit <= 0) { invalid("[!!] 0 or negative amount entered\nMaybe a typo?\n"); cout << "Deposit Amount: $"; cin >> initCheckDeposit; } } if(!checkFile) fatal("[!!] Fatal Error 251: Miscommunication with server\n"); checkFile << checkAcctName << endl; for(int j = 0; j < 13; j++) { acctNumber[j] = (rand() % 10); // Build a random checking account number checkFile << acctNumber[j]; } checkFile << endl; checkFile << initCheckDeposit << endl; checkFile.close(); } void Checking::viewCheckingBalance() { fstream checkFile("checking.dat", ios::in | ios::beg); string name; int i = 0; double balance = 0; system("cls"); cout << "\t\t -=[ View Checking Account ]=-\n\n" << endl; cout << "Account Name: "; cin.sync(); getline(cin, name); getline(checkFile, checkAcctName); while(name != checkAcctName && !checkFile.fail()) { i++; getline(checkFile, checkAcctName); } if(name == checkAcctName) { system("cls"); cout << "\t\t -=[ Checking Account Balance ]=-\n\n" << endl; cout << "Account Name: " << checkAcctName << "\n"; cout << "Account Number: "; for(int j = 0; j < 13; j++) { char input_number; stringstream converter; checkFile.get(input_number); converter << input_number; converter >> acctNumber[j]; cout << acctNumber[j]; } // if balance a problem, try the below commented out line // checkFile.ignore(numeric_limits<streamsize>::max(), '\n'); cout << endl; checkFile >> acctBalance; cout << "Balance: $" << fixed << showpoint << setprecision(2) << acctBalance << endl; } else fatal("[!!] Invalid Account\n"); checkFile.close(); getchar(); } void Checking::transferFromSaving() // Move funds FROM SAVINGS to CHECKING { system("cls"); string name; long checkPos = 0; long savePos = 0; float savingBalance = 0; string saveAcctName; int i = 0; cin.clear(); fstream saveFile("saving.dat", ios::in | ios::out | ios::beg); fstream checkFile("checking.dat", ios::in | ios::out | ios::beg); cout << "\t\t-=[ Funds Transfer ]=-" << endl; cout << "\t\t-=[ Savings to Checking ]=-" << endl; cout << "Account Name: "; cin.sync(); getline(cin, name); getline(checkFile, checkAcctName); while(name != checkAcctName && !checkFile.fail()) { i++; getline(checkFile, checkAcctName); } getline(saveFile, saveAcctName); while(name != saveAcctName && !saveFile.fail()) { i = 0; i++; getline(saveFile, saveAcctName); } if(name == checkAcctName) { cout << "Amount to transfer: $"; float depAmt = 0; cin >> depAmt; for(int j = 0; j < 13; j++) { char input_number; stringstream converter; checkFile.get(input_number); converter << input_number; converter >> acctNumber[j]; } checkPos = checkFile.tellg(); // if the file is found, get the position of acctBalance and store it in ptrPos checkFile.seekg(checkPos); checkFile >> acctBalance; savePos = saveFile.tellg(); saveFile.seekg(savePos); // sending the cursor in the file to ptrPos + 1 to ignore white space saveFile >> savingBalance; if(savingBalance < depAmt) // if checking account does not have enough funds, exit with NSF code fatal("[!!] Insufficient Funds\n"); acctBalance += depAmt; // can be changed to an overloaded operator savingBalance -= depAmt; // can be changed to an overloaded operator checkFile.seekp(checkPos); // go to position previously set above checkFile << acctBalance; // write new balance to checkFile saveFile.seekp(savePos); // same thing as above comment saveFile << savingBalance; // write new balance to saveFile cout << "New Balance in Checking: $" << acctBalance << endl; // will be removed later cout << "New Balance in Savings: $" << savingBalance << endl; // will be removed later aswell } else fatal("[!!] Linked accounts do not exist.\n"); // if account is not found saveFile.close(); checkFile.close(); } /******************************************************** ******************************************************** SAVING ACCOUNT CODE ********************************************************* *********************************************************/ void Saving::newSavingAccount() { system("cls"); ofstream saveFile("saving.dat", ios::out | ios::app); // For saving savings accounts cout << "\t\t -=[ New Savings Account ]=- \n" << endl; cout << "Name of the main holder to be on account: "; getline(cin, saveAcctName); cout << "Deposit Amount: $"; cin >> initSaveDeposit; if(initSaveDeposit <= 0) { while(initSaveDeposit <= 0) { invalid("[!!]0 or negative value entered.\nPerhaps a typo?\n"); cout << "Deposit amount: $"; cin >> initSaveDeposit; } } if(!saveFile) fatal("[!!] Fatal Error 251: Miscommunication with server\n"); saveFile << saveAcctName << endl; for(int j = 0; j < 13; j++) { acctNumber[j] = (rand() % 10); saveFile << acctNumber[j]; } saveFile << endl; saveFile << initSaveDeposit << endl; saveFile.close(); } void Saving::viewSavingBalance() { string name; int i = 0; fstream saveFile("saving.dat", ios::in | ios::beg); cin.clear(); system("cls"); cout << "\t\t -=[ View Saving Account ]=-\n\n" << endl; cout << "Account Name: "; cin.sync(); getline(cin, name); getline(saveFile, saveAcctName); while(name != saveAcctName && !saveFile.fail()) { i++; getline(saveFile, saveAcctName); } if(name == saveAcctName) { system("cls"); cout << "\t\t -=[ Saving Account Balance ]=-\n\n" << endl; cout << "Account Name: " << saveAcctName << "\n"; cout << "Account Number: "; for(int j = 0; j < 13; j++) { char input_number; stringstream converter; saveFile.get(input_number); converter << input_number; converter >> acctNumber[j]; cout << acctNumber[j]; } // if balance a problem, try the below commented out line // checkFile.ignore(numeric_limits<streamsize>::max(), '\n'); cout << endl; saveFile >> acctBalance; cout << "Balance: $" << fixed << showpoint << setprecision(2) << acctBalance << endl; } else fatal("[!!] Invalid Account\n"); saveFile.close(); getchar(); } // NEED TO WORK ON THIS PORTION TOMORROW AND MONDAY, ADD OVERLOADED OPS FOR ASSIGNMENT!!!!!!! void Saving::transferFromChecking() // This is to take money FROM checking and ADD IT TO SAVING { system("cls"); string name; long savePos = 0; long checkPos = 0; float checkingBalance = 0; string checkAcctName; int i = 0; cin.clear(); fstream saveFile("saving.dat", ios::in | ios::out | ios::beg); fstream checkFile("checking.dat", ios::in | ios::out | ios::beg); cout << "\t\t-=[ Funds Transfer ]=-" << endl; cout << "\t\t-=[ Checking to Savings ]=-" << endl; cout << "Account Name: "; cin.sync(); getline(cin, name); getline(saveFile, saveAcctName); getline(checkFile, checkAcctName); while(name != saveAcctName && name != checkAcctName && !saveFile.fail() && !checkFile.fail()) { i++; getline(saveFile, saveAcctName); getline(checkFile, checkAcctName); } if(name == saveAcctName) { cout << "Amount to transfer: $"; float depAmt = 0; cin >> depAmt; for(int j = 0; j < 13; j++) { char input_number; stringstream converter; saveFile.get(input_number); converter << input_number; converter >> acctNumber[j]; } savePos = saveFile.tellg(); // if the file is found, get the position of acctBalance and store it in ptrPos saveFile.seekg(savePos); saveFile >> acctBalance; checkPos = checkFile.tellg(); checkFile.seekg(checkPos); // if file is found, store current position of the cursor to ptrPos checkFile >> checkingBalance; if(checkingBalance < depAmt) // if checking account does not have enough funds, exit with NSF code fatal("[!!] Insufficient Funds\n"); // Can also place overloaded op here acctBalance += depAmt; // can be changed to an overloaded operator checkingBalance -= depAmt; // can be changed to an overloaded operator saveFile.seekg(savePos); // go to position previously set above saveFile << acctBalance; // write new balance to saveFile checkFile.seekg(checkPos); // same thing as above comment checkFile << checkingBalance; // write new balance to checkFile cout << "New Balance in Savings: $" << acctBalance << endl; // will be removed later cout << "New Balance in Checking: $" << checkingBalance << endl; // will be removed later aswell } else fatal("[!!] Linked accounts do not exist.\n"); // if account is not found saveFile.close(); checkFile.close(); } /******************************************** ******************************************** CHECK AND SAVE CODE ********************************************** **********************************************/ void checkAndSave::newCheckAndSave() { system("cls"); ofstream saveFile("saving.dat", ios::out | ios::app); // For saving savings accounts ofstream checkFile("checking.dat", ios::out | ios::app); // For saving checking accounts cout << "\t -=[ New Checking & Saving Account ]=- \n" << endl; cout << "Name of the main holder to be on account: "; getline(cin, checkAcctName); saveAcctName = checkAcctName; cout << "Checking Deposit Amount: $"; cin >> initCheckDeposit; if(initCheckDeposit <= 0) { while(initCheckDeposit <= 0) { invalid("[!!] 0 or negative amount entered\nMaybe a typo?\n"); cout << "Deposit Amount: $"; cin >> initCheckDeposit; } } cout << "Saving Deposit Amount: $"; cin >> initSaveDeposit; if(initSaveDeposit <= 0) { while(initSaveDeposit <= 0) { invalid("[!!]0 or negative value entered.\nPerhaps a typo?\n"); cout << "Deposit amount: $"; cin >> initSaveDeposit; } } if(!saveFile || !checkFile) fatal("[!!] Fatal Error 251: Miscommunication with server\n"); checkFile << checkAcctName << endl; saveFile << saveAcctName << endl; for(int j = 0; j < 13; j++) { acctNumber[j] = (rand() % 10); checkFile << acctNumber[j]; saveFile << acctNumber[j]; } saveFile << endl; saveFile << initSaveDeposit << endl; checkFile << endl; checkFile << initCheckDeposit << endl; checkFile.close(); saveFile.close(); } void checkAndSave::viewBothBalances() { string name; int i = 0; fstream checkFile("checking.dat", ios::in | ios::beg); fstream saveFile("saving.dat", ios::in | ios::beg); system("cls"); cin.clear(); cout << "\t-=[ Saving & Checking Account Balance ]=-\n\n" << endl; cout << "Account Name: "; cin.sync(); getline(cin, name); getline(checkFile, checkAcctName); saveAcctName = name; /**********************\ | Checking Account portion | | of the checking & savings | | overview | \**********************/ while(name != checkAcctName && !checkFile.fail()) { i++; getline(checkFile, checkAcctName); } system("cls"); if(name != checkAcctName && checkFile.fail()) invalid("\n\n[!!] No Checking Account Found\n"); cout << "\t\t -=[ Checking Account ]=- \n" << endl; cout << "Account Name: " << checkAcctName << "\n"; cout << "Account Number: "; for(int j = 0; j < 13; j++) { char input_number; stringstream converter; checkFile.get(input_number); converter << input_number; converter >> acctNumber[j]; cout << acctNumber[j]; } // if balance a problem, try the below commented out line // checkFile.ignore(numeric_limits<streamsize>::max(), '\n'); cout << endl; checkFile >> acctBalance; cout << "Balance: $" << fixed << showpoint << setprecision(2) << acctBalance << endl; /*********************\ | Saving Account portion | | of the checking & saving | | overview | \*********************/ getline(saveFile, saveAcctName); while(name != saveAcctName && !saveFile.fail()) { i++; getline(saveFile, saveAcctName); } if(name != saveAcctName && saveFile.fail()) invalid("\n\n[!!] No Saving Account Found\n"); if(name == saveAcctName) { cout << "\t\t -=[ Saving Account ]=-\n\n" << endl; cout << "Account Name: " << saveAcctName << "\n"; cout << "Account Number: "; for(int j = 0; j < 13; j++) { char input_number; stringstream converter; saveFile.get(input_number); converter << input_number; converter >> acctNumber[j]; cout << acctNumber[j]; } // if balance a problem, try the below commented out line // checkFile.ignore(numeric_limits<streamsize>::max(), '\n'); cout << endl; saveFile >> acctBalance; cout << "Balance: $" << fixed << showpoint << setprecision(2) << acctBalance << endl; } if(name != saveAcctName && name != checkAcctName && saveFile.fail() && checkFile.fail()) fatal("[!!] No Accounts Have Been Found\n"); checkFile.close(); saveFile.close(); getchar(); } Main.cpp #include <iostream> #include "MainBankClass.h" using namespace std; int main() { Banking bank; Checking check; Saving save; checkAndSave CanS; char choice; choice = bank.menu(); // Call the banking menu switch(choice) { case 'A': choice = bank.newAccountMenu(); switch(choice) { case 'A': check.newCheckingAccount(); break; case 'B': save.newSavingAccount(); break; case 'C': CanS.newCheckAndSave(); break; default: system("cls"); bank.fatal("[!!] Invalid option\n"); break; } break; /***********************************************/ case 'B': choice = bank.getBalanceChoice(); switch(choice) { case 'A': check.viewCheckingBalance(); break; case 'B': save.viewSavingBalance(); break; case 'C': CanS.viewBothBalances(); break; default: bank.fatal("Invalid decision\n"); break; } /*************************************************/ break; case 'C': check.transferFromSaving(); break; case 'D': save.transferFromChecking(); break; case 'E': system("cls"); cout << "\t\t-=[ Disconnecting From System ]=-\n"; cout << "\t\t\t Thank you" << endl; cout << "\t\t Have a nice day!" << endl; exit(1); break; default: system("cls"); bank.invalid("\n\n\n\n\t\t [+] Invalid Selection \n\t\t[+] Disconnecting From System \n\t\t\tGood-bye \n\n\n\n\n\n\n"); exit(1); break; } return 0; }

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  • Bash and regex problem : check for tokens entered into a Coke vending machine

    - by Michael Mao
    Hi all: Here is a "challenge question" I've got from Linux system programming lecture. Any of the following strings will give you a Coke if you kick: L = { aaaa, aab, aba, baa, bb, aaaa"a", aaaa"b", aab"a", … ab"b"a, ba"b"a, ab"bbbbbb"a, ... } The letters shown in wrapped double quotes indicate coins that would have fallen through (but those strings are still part of the language in this example). Exercise (a bit hard) show this is the language of a regular expression And this is what I've got so far : #!/usr/bin/bash echo "A bottle of Coke costs you 40 cents" echo -e "Please enter tokens (a = 10 cents, b = 20 cents) in a sequence like 'abba' :\c" read tokens #if [ $tokens = aaaa ]||[ $tokens = aab ]||[ $tokens = bb ] #then # echo "Good! now a coke is yours!" #else echo "Thanks for your money, byebye!" if [[ $token =~ 'aaaa|aab|bb' ]] then echo "Good! now a coke is yours!" else echo "Thanks for your money, byebye!" fi Sadly it doesn't work... always outputs "Thanks for your money, byebye!" I believe something is wrong with syntax... We didn't provided with any good reference book and the only instruction from the professor was to consult "anything you find useful online" and "research the problem yourself" :( I know how could I do it in any programming language such as Java, but get it done with bash script + regex seems not "a bit hard" but in fact "too hard" for anyone with little knowledge on something advanced as "lookahead"(is this the terminology ?) I don't know if there is a way to express the following concept in the language of regex: Valid entry would consist of exactly one of the three components : aaaa, aab and bb, regardless of order, followed by an arbitrary sequence of a or b's So this is what is should be like : (a{4}Ua{2}bUb{2})(aUb)* where the content in first braces is order irrelevant. Thanks a lot in advance for any hints and/or tips :)

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  • RegularExpression-esque search matching Objects in List

    - by Pindatjuh
    I'm currently working on an implementation of the following idea, and I was wondering if there is any literature on this subject. Working with Java, but the principle applies on any language with a decent type-system, I like to implement: matching Objects from a List using a RegularExpression-esque search: So let's say I have a List containing List<Object> x = new ArrayList<Object>(); x.add(new Object()); x.add("Hello World"); x.add("Second String"); x.add(5); // Integer (auto-boxing) x.add(6); // Integer Then I create a "Regular Expression" (not working with a stream of characters, but working with a stream of Objects), and instead of character-classes, I use type-system properties: [String][Integer] And this would match one sublist: {Match["Second String", 5]}. The expression: [String:length()<15] Will match two sublist (each of length 1) containing a String which instance is passing the expression instance.length() < 5: {Match["Hello World"],Match["Second String"]}. [Object][Object] Matches any pair in the List: {Match[Object,"Hello World"],Match["Second String", 5]}, in a streamed manner (no overlapping matches). Ofcourse, my implementation will have grouping, lookahead/lookbehinds and is hierarchical (i.e. matching n elements from Lists in Lists), etc. The above merely illustrates the concept. Is there a name for this principle, and is there literature available on it?

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  • Regular expression to match empty HTML tags that may contain embedded JSTL?

    - by Keith Bentrup
    I'm trying to construct a regular expression to look for empty html tags that may have embedded JSTL. I'm using Perl for my matching. So far I can match any empty html tag that does not contain JSTL with the following? /<\w+\b(?!:)[^<]*?>\s*<\/\w+/si The \b(?!:) will avoid matching an opening JTSL tag but that doesn't address the whether JSTL may be within the HTML tag itself (which is allowable). I only want to know if this HTML tag has no children (only whitespace or empty). So I'm looking for a pattern that would match both the following: <div id="my-id"> </div> <div class="<c:out var="${my.property}" />"></div> Currently the first div matches. The second does not. Is it doable? I tried several variations using lookahead assertions, and I'm starting to think it's not. However, I can't say for certain or articulate why it's not. Edit: I'm not writing something to interpret the code, and I'm not interested in using a parser. I'm writing a script to point out potential issues/oversights. And at this point, I'm curious, too, to see if there is something clever with lookaheads or lookbehinds that I may be missing. If it bothers you that I'm trying to "solve" a problem this way, don't think of it as looking for a solution. To me it's more of a challenge now, and an opportunity to learn more about regular expressions. Also, if it helps, you can assume that the html is xhtml strict.

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  • std::list iterator: get next element

    - by sheepsimulator
    I'm trying to build a string using data elements stored in a std::list, where I want commas placed only between the elements (ie, if elements are {A,B,C,D} in list, result string should be "A,B,C,D". This code does not work: typedef std::list< shared_ptr<EventDataItem> > DataItemList; // ... std::string Compose(DataItemList& dilList) { std::stringstream ssDataSegment; for(iterItems = dilList.begin(); iterItems != dilList.end(); iterItems++) { // Lookahead in list to see if next element is end if((iterItems + 1) == dilList.end()) { ssDataSegment << (*iterItems)->ToString(); } else { ssDataSegment << (*iterItems)->ToString() << ","; } } return ssDataSegment.str(); } How do I get at "the-next-item" in a std::list using an iterator? I would expect that it's a linked-list, why can't I get at the next item?

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  • std::list : get next element

    - by sheepsimulator
    I'm trying to build a string using data elements stored in a std::list, where I want commas placed only between the elements (ie, if elements are {A,B,C,D} in list, result string should be "A,B,C,D". This code does not work: typedef std::list< shared_ptr<EventDataItem> > DataItemList; // ... std::string Compose(DataItemList& dilList) { std::stringstream ssDataSegment; for(iterItems = dilList.begin(); iterItems = dilList.end(); iterItems++) { // Lookahead in list to see if next element is end if((iterItems + 1) == dilList.end()) { ssDataSegment << (*iterItems)->ToString(); } else { ssDataSegment << (*iterItems)->ToString() << ","; } } return ssDataSegment.str(); } How do I get at "the-next-item" in a std::list using an iterator? I would expect that it's a linked-list, why can't I get at the next item?

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  • Selectively search and replace certain lines using a regular expression

    - by eneveu
    I have a file containing a lot of SQL statements, such as: CREATE TABLE "USER" ( "ID" INTEGER PRIMARY KEY, "NAME" CHARACTER VARYING(50) NOT NULL, "AGE" INTEGER NOT NULL ); COPY "USER" (id, name, age) FROM stdin; 1 Skywalker 19 2 Kenobi 57 I want the column names in the COPY statements to be uppercased and quoted: COPY "USER" ("ID", "NAME", "AGE") FROM stdin; Using sed, I found the following regexp: sed -r 's/([( ])(\w+)([,)])/\1"\U\2\E"\3/g' It does replace the column names, but it is not selective enough, and replaces other words in the file: ~/test]$sed -r 's/([( ])(\w+)([,)])/\1"\U\2\E"\3/g' star_wars_example CREATE TABLE "USER" ( "ID" INTEGER PRIMARY "KEY", "NAME" CHARACTER VARYING("50")NOT "NULL", "AGE" INTEGER NOT NULL ); COPY "USER" ("ID", "NAME", "AGE") FROM stdin; 1 Skywalker 19 2 Kenobi 57 To avoid this problem, I want sed to only apply my regexp to the lines starting with COPY and ending with FROM stdin;. I have looked into lookahead / lookbehind, but they are not supported in sed. They seem to be supported in super-sed, but I am currently using Cygwin (Windows is mandatory here...) and it does not seem available in the package list. Is there a way to force sed to only consider specific line? I've considered piping my file through grep before applying sed, but other lines will then disappear from the output. Am I missing something obvious? It would be great if the answer was easily applicable on a default Cygwin install. I guess I could try installing super-sed on cygwin, but I'd like to know if there are more obvious ideas

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  • F# ref-mutable vars vs object fields

    - by rwallace
    I'm writing a parser in F#, and it needs to be as fast as possible (I'm hoping to parse a 100 MB file in less than a minute). As normal, it uses mutable variables to store the next available character and the next available token (i.e. both the lexer and the parser proper use one unit of lookahead). My current partial implementation uses local variables for these. Since closure variables can't be mutable (anyone know the reason for this?) I've declared them as ref: let rec read file includepath = let c = ref ' ' let k = ref NONE let sb = new StringBuilder() use stream = File.OpenText file let readc() = c := stream.Read() |> char // etc I assume this has some overhead (not much, I know, but I'm trying for maximum speed here), and it's a little inelegant. The most obvious alternative would be to create a parser class object and have the mutable variables be fields in it. Does anyone know which is likely to be faster? Is there any consensus on which is considered better/more idiomatic style? Is there another option I'm missing?

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  • shell script segment to avoid overwriting files

    - by johndashen
    I have a perl script (or any executable) E which will take a file foo.xml and write a file foo.txt. I use a Beowulf cluster to run E for a large number of XML files, but I'd like to write a simple job server script in shell (bash) which doesn't overwrite existing txt files. I'm currently doing something like #!/bin/sh PATTERN="[A-Z]*0[1-2][a-j]"; # this matches foo in all cases todo=`ls *.xml | grep $PATTERN`; isdone=`ls *.foo | grep $PATTERN`; whatsleft=todo - isdone; # what's the unix magic? #and then call the job server; jobserve E "$whatsleft"; and then I don't know how to get the difference between $todo and $isdone. I'd prefer using sort/uniq to something like a for loop with grep inside, but I'm not sure how to do it (pipes? temporary files?) As a bonus question, is there a way to do lookahead search in bash grep?

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  • Unix : `nc` on Ubuntu vs Redhat (netcat)

    - by bguiz
    How do I achieve the equivalent of nc -q in Redhat 5? Details? nc -q -1 local host ${PORT} ${CMD} In Ubuntu, nc may be use as above, with the -q option. See manpage. -q after EOF on stdin, wait the specified number of seconds and then quit. If seconds is negative, wait forever. However, this option is not available in Redhat 5. See manpage. (Note: The Red Hat website is horrible to search, if someone finds their manpage for nc, please edit this post or comment with the new link).

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  • Canon LiDE 600F FAU on Snow Leopard?

    - by jdmuys
    Hello, I have been able to use my Canon LiDE 600F scanner under Snow Leopard to scan paper sheet, after installing Canon's latest driver software. However, I cannot find a way to make the FAU (Film Adaptor Unit) to work: Canon's software want to calibrate it first and gives an error message "Calibration cannot be performed. Pull out the film. 182.0.0". (of course there is no film). Hamrick's VueScan doesn't seem to support the FAU Apple's Image Capture doesn't propose a film option either Did I miss something? Did somebody manage to scan film (positive or negative) using the LiDE 600F under Snow Leopard? Many thanks

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  • How safe is it to run CHKDSK on an SSD?

    - by Eilon
    I recently saw Windows 7 pop up a warning or two that I should run chkdsk on my laptop. My laptop came with an SSD and I'm not sure if there are any negative implications to running chkdsk on such a drive. Are there any potential issues with reporting "bad sectors" on the drive? I would imagine that the physical concept of sectors is completely different between a platter and a microchip. I don't think my SSD supports TRIM. It's about 14 months old and a quick web search seems to hint that it doesn't (though it's nearly impossible to find out this info for sure!). I'm also not sure if TRIM is even relevant here since there shouldn't be much in the way of deletes. So, how safe is it to run chkdsk on my SSD drive? The model of SSD that I have is reported as "Samsung SSD PB22-JS3 2.5".

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  • How to make ClearType looks ok even with large fonts

    - by Sorin Sbarnea
    I discovered that on large/huge fonts ClearType does have a negative impact. Just take a look at http://patterns.dataincubator.org/book/ page (check title with huge fonts versus normal text). If you are on Windows 7 you can use Win+Plus/Minus to zoom in/out. I'm looking for a configuration that would make both small fonts and large fonts look well. The system is Windows 7 but I suppose you could replicate the problem on Vista and even XP if you activate ClearType. Current results: ClearType on and tunned - small fonts looking good and large one looking bad ClearType off - small fonts looking bad and large one looking ok (smoothed)

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  • TCP Zero Window with no corresponding Window Update

    - by Gandalf
    I am trying to debug a network issue and am using Wireshark and tcpdump to grab packets from my server. I have one client application that is grabbing all my available connections and then holding them, trying to send A LOT of data and essentially causing an unintentional DOS attack. While debugging I notice that I see my server sending "Window Closed" and "Zero Window" TCP packets - but never sending any "Window Update" packets. I am guessing this is why the client never lets go of the connections (it still has more data to send and is waiting). Has anyone ever seen this type of behavior before? Let's not get into the reasons why I haven't set up an iptables rule to limit concurrent connections (yeah I know). I also recently changed the MTU from 1500 to 9000 - could this have such a negative effect? (Linux) Thanks.

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  • rm failing inside cron script

    - by Nicholas
    I have a cron job calling a bash script which runs fine, except for one line inside it that is suppose to remove all fines in a directory. The result of this line is always 'no such file or directory' even though I have verified (many times) that there are files in that directory. The line in question is as simply: rm /dir1/dir2/dir3/* The script works fine when run manually in the terminal, so it must be something about how the cron is run. I've tried giving 'dir3' and all the files inside it every permission possible, so it shouldn't be a permission problem. (The directory and files are also owned by the user). I've tried specifing 'SHELL=/bin/bash' inside 'crontab'. There is no sticky bit set and there is no alias on the rm command. Interestingly changing the 'rm' command to 'ls' gives the same negative result (unless you remove the trailing '*', and then that works). What am I missing here?

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  • What is polarity for an unmarked USB hub?

    - by Feral Oink
    On my USB hub where the power supply plugs in, the polarity is unmarked (I got it used, from my brother's friend). I need to know what the polarity should be. I don't think it makes a difference about the brand. Could someone who has a USB hub tell me what the polarity markings are? This is why I need to know about the polarity: Usually the center pin is positive and the outer pin is negative. But I'm not sure with this, and want to be certain before I plug anything into it.

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