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  • When is a Cocoa callback given controll?

    - by Kaspa
    Hi, I've been searching around the web for an answer to this one, but was unable to find an answer, on the other side I think it's something quite common thus there is a possibility I'm missing some keywords here. Anyhow, the problem is as follows: When is control given to a callback function in ObjC (iPhone)? Does it happen after control is given to a high up in the hierarchy class responsible for the runloop? Can it occur in the middle of another function call being executed? As an example, let's take the NSURLConnection, we don't know or can't predict when it's going to call didReceiveResponse or the other callback methods, can it be the case that didReceiveResponse get's called when I'm in the middle of another function? (highly doubt that but was unable to find information on callbacks wating for the end of the run loop) Cheers, Kaspa

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  • Oracle checking existence before deletion in a trigger

    I have analyzed a hibernate generated oracle database and discovered that a delete of a row from a single table will spawn the firing of 1200+ triggers in order to delete the related rows in child tables. The triggers are all auto-generated the same - an automatic delete of a child row without checking for existence first. As it is impossible to predict which child tables will actually have related rows, I think a viable solution to preventing the firing of the cascaded delete down a deeply branched completely empty limb, would be to check for the existence of a related row before attempting to delete. In other dbms', I could simply state " if exists....." before deleting. Is there a comparable way to do this in oracle?

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  • The Business case for Big Data

    - by jasonw
    The Business Case for Big Data Part 1 What's the Big Deal Okay, so a new buzz word is emerging. It's gone beyond just a buzzword now, and I think it is going to change the landscape of retail, financial services, healthcare....everything. Let me spend a moment to talk about what i'm going to talk about. Massive amounts of data are being collected every second, more than ever imaginable, and the size of this data is more than can be practically managed by today’s current strategies and technologies. There is a revolution at hand centering on this groundswell of data and it will change how we execute our businesses through greater efficiencies, new revenue discovery and even enable innovation. It is the revolution of Big Data. This is more than just a new buzzword is being tossed around technology circles.This blog series for Big Data will explain this new wave of technology and provide a roadmap for businesses to take advantage of this growing trend. Cases for Big Data There is a growing list of use cases for big data. We naturally think of Marketing as the low hanging fruit. Many projects look to analyze twitter feeds to find new ways to do marketing. I think of a great example from a TED speech that I recently saw on data visualization from Facebook from my masters studies at University of Virginia. We can see when the most likely time for breaks-ups occurs by looking at status changes and updates on users Walls. This is the intersection of Big Data, Analytics and traditional structured data. Ted Video Marketers can use this to sell more stuff. I really like the following piece on looking at twitter feeds to measure mood. The following company was bought by a hedge fund. They could predict how the S&P was going to do within three days at an 85% accuracy. Link to the article Here we see a convergence of predictive analytics and Big Data. So, we'll look at a lot of these business cases and start talking about what this means for the business. It's more than just finding ways to use Hadoop + NoSql and we'll talk about that too. How do I start in Big Data? That's what is coming next post.

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  • SQL SERVER – 4 Tips for ETL Software IDE Developers

    - by pinaldave
    In a previous blog, I introduced the notion of Semantic Types. To an end-user, a seamlessly integrated semantic typing engine significantly increases the ease of use of an ETL IDE (integrated development environment, or developer studio). This led me to think about other ease-of-use issues I have encountered while building ETL applications. When I get stumped while programming, I find myself asking the variations on these questions: “How do I…?” “Now what?” “Why isn’t this working?” “Why do I have to redo the work I just did?” It seems to me that a good ETL IDE will anticipate these questions and seek to answer them before they are even asked. So here are my tips to help software vendors build developer IDEs that actually make development easier. How do I…? While developing an ETL application, have you ever asked yourself: “How do I set up the connection to my SQL Server database?”,“How do I import my table definitions from Access?”, etc. An easy answer might be “read the manual” but sometimes product manuals are not robust or easily accessible. So, integrating robust how-to instructions directly into your ETLstudio would help users get the information they need at the time they need it. Now what? IDEs in general know where you last clicked or performed an action using an input device such as a keyboard; so they should be able to reasonably predict the design context you are in and suggest the next steps accordingly. Context-sensitive suggestions based on the state of the user’s work will help users move forward in ETL application development. Why isn’t this working? Or why do I have to wait till I compile to be told about a critical design issue? If an ETL IDE is smart enough to signal to users what in their design structures is left to be completed or has been completed incorrectly, then the developer can spend much less time in the designàcompileàerror-correct loop. Just-in-time validation helps users detect and correct programming errors earlier in the ETL development life cycle. Why do I have to redo the work I just did? In ETL development, schemas, transformation rules, connectivity objects, etc., can be reused in various situations. Using mouse-clicks to build and manage libraries of reusable design objects implies that the application development effort should decrease over time and as the library acquires more objects. I met a great company at SQL Pass that is trying to address many of these usability issues. Check them out at www.expressor-software.com. What other ease-of-use suggestions do you have for ETL software vendors? Please post your valuable comments. ?Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Best Practices, Pinal Dave, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology Tagged: ETL

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  • First impressions of Scala

    - by Scott Weinstein
    I have an idea that it may be possible to predict build success/failure based on commit data. Why Scala? It’s a JVM language, has lots of powerful type features, and it has a linear algebra library which I’ll need later. Project definition and build Neither maven or the scala build tool (sbt) are completely satisfactory. This maven **archetype** (what .Net folks would call a VS project template) mvn archetype:generate `-DarchetypeGroupId=org.scala-tools.archetypes `-DarchetypeArtifactId=scala-archetype-simple `-DremoteRepositories=http://scala-tools.org/repo-releases `-DgroupId=org.SW -DartifactId=BuildBreakPredictor gets you started right away with “hello world” code, unit tests demonstrating a number of different testing approaches, and even a ready made `.gitignore` file - nice! But the Scala version is behind at v2.8, and more seriously, compiling and testing was painfully slow. So much that a rapid edit – test – edit cycle was not practical. So Lab49 colleague Steve Levine tells me that I can either adjust my pom to use fsc – the fast scala compiler, or use sbt. Sbt has some nice features It’s fast – it uses fsc by default It has a continuous mode, so  `> ~test` will compile and run your unit test each time you save a file It’s can consume (and produce) Maven 2 dependencies the build definition file can be much shorter than the equivalent pom (about 1/5 the size, as repos and dependencies can be declared on a single line) And some real limitations Limited support for 3rd party integration – for instance out of the box, TeamCity doesn’t speak sbt, nor does IntelliJ IDEA Steeper learning curve for build steps outside the default Side note: If a language has a fast compiler, why keep the slow compiler around? Even worse, why make it the default? I choose sbt, for the faster development speed it offers. Syntax Scala APIs really like to use punctuation – sometimes this works well, as in the following map1 |+| map2 The `|+|` defines a merge operator which does addition on the `values` of the maps. It’s less useful here: http(baseUrl / url >- parseJson[BuildStatus] sure you can probably guess what `>-` does from the context, but how about `>~` or `>+`? Language features I’m still learning, so not much to say just yet. However case classes are quite usefull, implicits scare me, and type constructors have lots of power. Community A number of projects, such as https://github.com/scalala and https://github.com/scalaz/scalaz are split between github and google code – github for the src, and google code for the docs. Not sure I understand the motivation here.

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  • A Plea for Plain English

    - by Tony Davis
    The English language has, within a lifetime, emerged as the ubiquitous 'international language' of scientific, political and technical communication. On the one hand, learning a single, common language, International English, has made it much easier to participate in and adopt new technologies; on the other hand it must be exasperating to have to use English at international conferences, or on community sites, when your own language has a long tradition of scientific and technical usage. It is also hard to master the subtleties of using a foreign language to explain advanced ideas. This requires English speakers to be more considerate in their writing. Even if you’re used to speaking English, you may be brought up short by this sort of verbiage… "Business Intelligence delivering actionable insights is becoming more critical in the enterprise, and these insights require large data volumes for trending and forecasting" It takes some imagination to appreciate the added hassle in working out what it means, when English is a language you only use at work. Try, just to get a vague feel for it, using Google Translate to translate it from English to Chinese and back again. "Providing actionable business intelligence point of view is becoming more and more and more business critical, and requires that these insights and projected trends in large amounts of data" Not easy eh? If you normally use a different language, you will need to pause for thought before finally working out that it really means … "Every Business Intelligence solution must be able to help companies to make decisions. In order to detect current trends, and accurately predict future ones, we need to analyze large volumes of data" Surely, it is simple politeness for English speakers to stop peppering their writing with a twisted vocabulary that renders it inaccessible to everyone else. It isn’t just the problem of writers who use long words to give added dignity to their prose. It is the use of Colloquial English. This changes and evolves at a dizzying rate, adding new terms and idioms almost daily; it is almost a new and separate language. By contrast, ‘International English', is gradually evolving separately, at its own, more sedate, pace. As such, all native English speakers need to make an effort to learn, and use it, switching from casual colloquial patter into a simpler form of communication that can be widely understood by different cultures, even if it gives you less credibility on the street. Simple-Talk is based, at least in part, on the idea that technical articles can be written simply and clearly in a form of English that can be easily understood internationally, and that they can be written, with a little editorial help, by anyone, and read by anyone, regardless of their native language. Cheers, Tony.

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  • Using SQL Source Control and Vault Professional Part 4

    - by Ajarn Mark Caldwell
    Two weeks ago I upgraded our installation of Fortress to the latest version, which is now named Vault Professional.  This is the version of Vault (i.e. Vault Standard 5.1 / Vault Professional 5.1) that will be officially supported with Red-Gate SQL Source Control 2.1.  While the folks at Red-Gate did a fantastic job of working with me to get SQL Source Control to work with the older Fortress version, we weren’t going to just sit on that.  There are a couple of things that Vault Professional cleaned up for us, such as improved integration with Visual Studio 2010, so it was a win all around. Shortly after that upgrade, I received notice from Red-Gate that they had a new Early Access version of SQL Source Control available that included the ability to source control static data.  The idea here is that you probably have a few fairly static lookup tables in your system, and those data values are similar in concept to source code, and should be versioned in your source control management system also.  I agree with this, but please be wise…somebody out there is bound to try to use this feature as their disaster recovery for their entire database, and that is NOT the purpose.  First off, you should never have your PROD (or LIVE, whatever you call it) system attached to source control.  Source Control is for development, not for PROD systems.  Second, use the features that are intended for this purpose, such as BACKUP and RESTORE. Laying that tangent aside, it is great that now you can include these critical values in your repository and make them part of a deployment process.  As you would guess, SQL Source Control uses SQL Data Compare to create the data change scripts just like it uses SQL Compare to create the schema change scripts.  Once again, they did a very good job with the integration to their other products.  At this point we are really starting to see some good payback on our investment in the full SQL Developer Bundle.  Those products were worth the investment back when we only used them sporadically for troubleshooting and DBA analysis, but now with SQL Source Control, they are becoming everyday-use products for the development team. I like this software (SQL Source Control) so much that I am about to break my own rules and distribute it to my team to use even though it is still in beta.  This is the first time that I have approved the use of any beta software in a production scenario (actively building our next versions of internal software) but I predict that the usability and productivity gain of using SQL Source Control over manual scripting is worth the risk.  Of course, I have also put this beta software through its paces pretty well to be comfortable with it, and Red-Gate has proven their responsiveness to issues that came up in my early beta testing, and so I am willing to bet on their continued support.  Likewise, SourceGear, the maker of Vault Professional, has proven itself to me as well, and so the combination of SQL Source Control with Vault Professional is the new standard for my development team.

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  • SQLAuthority News – I am Presenting 2 Sessions at TechEd India

    - by pinaldave
    TechED is the event which I am always excited about. It is one of the largest technology in India. Microsoft Tech Ed India 2011 is the premier technical education and networking event for tech professionals interested in learning, connecting and exploring a broad set of current and soon-to-be released Microsoft technologies, tools, platforms and services. I am going to speak at the TechED on two very interesting and advanced subjects. Venue: The LaLiT Ashok Kumara Krupa High Grounds Bangalore – 560001, Karnataka, India Sessions Date: March 25, 2011 Understanding SQL Server Behavioral Pattern – SQL Server Extended Events Date and Time: March 25, 2011 12:00 PM to 01:00 PM History repeats itself! SQL Server 2008 has introduced a very powerful, yet very minimal reoccurring feature called Extended Events. This advanced session will teach experienced administrators’ capabilities that were not possible before. From T-SQL error to CPU bottleneck, error login to deadlocks –Extended Event can detect it for you. Understanding the pattern of events can prevent future mistakes. SQL Server Waits and Queues – Your Gateway to Perf. Troubleshooting Date and Time: March 25, 2011 04:15 PM to 05:15 PM Just like a horoscope, SQL Server Waits and Queues can reveal your past, explain your present and predict your future. SQL Server Performance Tuning uses the Waits and Queues as a proven method to identify the best opportunities to improve performance. A glance at Wait Types can tell where there is a bottleneck. Learn how to identify bottlenecks and potential resolutions in this fast paced, advanced performance tuning session. My session will be on the third day of the event and I am very sure that everybody will be in groove to learn new interesting subjects. I will have few give-away during and at the end of the session. I will not tell you what I will have but it will be for sure something you will love to have. Please make a point and reserve above time slots to attend my session. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: About Me, Pinal Dave, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, SQL Wait Stats, SQL Wait Types, T SQL, Technology Tagged: SQL Extended Events

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  • Tips on ensuring Model Quality

    - by [email protected]
    Given enough data that represents well the domain and models that reflect exactly the decision being optimized, models usually provide good predictions that ensure lift. Nevertheless, sometimes the modeling situation is less than ideal. In this blog entry we explore the problems found in a few such situations and how to avoid them.1 - The Model does not reflect the problem you are trying to solveFor example, you may be trying to solve the problem: "What product should I recommend to this customer" but your model learns on the problem: "Given that a customer has acquired our products, what is the likelihood for each product". In this case the model you built may be too far of a proxy for the problem you are really trying to solve. What you could do in this case is try to build a model based on the result from recommendations of products to customers. If there is not enough data from actual recommendations, you could use a hybrid approach in which you would use the [bad] proxy model until the recommendation model converges.2 - Data is not predictive enoughIf the inputs are not correlated with the output then the models may be unable to provide good predictions. For example, if the input is the phase of the moon and the weather and the output is what car did the customer buy, there may be no correlations found. In this case you should see a low quality model.The solution in this case is to include more relevant inputs.3 - Not enough cases seenIf the data learned does not include enough cases, at least 200 positive examples for each output, then the quality of recommendations may be low. The obvious solution is to include more data records. If this is not possible, then it may be possible to build a model based on the characteristics of the output choices rather than the choices themselves. For example, instead of using products as output, use the product category, price and brand name, and then combine these models.4 - Output leaking into input giving the false impression of good quality modelsIf the input data in the training includes values that have changed or are available only because the output happened, then you will find some strong correlations between the input and the output, but these strong correlations do not reflect the data that you will have available at decision (prediction) time. For example, if you are building a model to predict whether a web site visitor will succeed in registering, and the input includes the variable DaysSinceRegistration, and you learn when this variable has already been set, you will probably see a big correlation between having a Zero (or one) in this variable and the fact that registration was successful.The solution is to remove these variables from the input or make sure they reflect the value as of the time of decision and not after the result is known. 

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  • SQL SERVER – Validating Spatial Object with IsValidDetailed Function

    - by pinaldave
    What do you prefer – error or warning indicating error may happen with the reason for the error. While writing the previous statement I remember the movie “Minory Report”. This blog post is not about minority report but I will still cover the concept in a single statement “Let us predict the future and prevent the crime which is about to happen in future”. (Please feel free to correct me if I am wrong about the movie concept, I really do not want to hurt your sentiment if you are dedicated fan). Let us switch to the SQL Server world. Spatial data types are interesting concepts. I love writing about spatial data types because it allows me to be creative with shapes (just like toddlers). When working with Spatial Datatypes it is all good when the spatial object works fine. However, when the spatial object has issue or it is created with invalid coordinates it used to give a simple error that there is an issue with the object but did not provide much information. This made it very difficult to debug. If this spatial object was used in the big procedure and while this big procedural error out because of the invalid spatial object, it is indeed very difficult to debug it. I always wished that the more information provided regarding what is the problem with spatial datatype. SQL Server 2012 has introduced the new function IsValidDetailed(). This function has made my life very easy. In simple words this function will check if the spatial object passed is valid or not. If it is valid it will give information that it is valid. If the spatial object is not valid it will return the answer that it is not valid and the reason for the same. This makes it very easy to debug the issue and make the necessary correction. DECLARE @p GEOMETRY = 'Polygon((2 2, 6 6, 4 2, 2 2))' SELECT @p.IsValidDetailed() GO DECLARE @p GEOMETRY = 'Polygon((2 2, 3 3, 4 4, 5 5, 6 6, 2 2))' SELECT @p.IsValidDetailed() GO DECLARE @p GEOMETRY = 'Polygon((2 2, 4 4, 4 2, 2 3, 2 2))' SELECT @p.IsValidDetailed() GO DECLARE @p GEOMETRY = 'CIRCULARSTRING(2 2, 4 4, 0 0)' SELECT @p.IsValidDetailed() GO DECLARE @p GEOMETRY = 'CIRCULARSTRING(2 2, 4 4, 0 0)' SELECT @p.IsValidDetailed() GO DECLARE @p GEOMETRY = 'LINESTRING(2 2, 4 4, 0 0)' SELECT @p.IsValidDetailed() GO Here is the resultset of the above query. You can see any valid query and some invalid query. If the query is invalid it also demonstrates the reason along with the error message. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology Tagged: Spatial Database, SQL Spatial

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  • What to answer to a customer who asks which one of two equivalent technologies must be used?

    - by MainMa
    As a freelancer, I am often asked by my customers what they must choose between similar elements, neither of which being better than another. Examples: “Do I need my e-commerce website be in PHP or ASP.NET?” “Do I need to host this ordinary web service in Cloud or use an ordinary hosting service?” “Which one is better for my new website: MySQL or Oracle?” etc. There is maybe at most 1% of cases where the choice is relevant, and there is a real, objective reason to use one over another, based on the precise metrics and studies. In all other cases, it doesn't matter at all. It is totally, completely irrelevant, either because there are no implications¹, or because those implications are too small to be taken in account², or, finally, because it's impossible to predict those implications³. If you know one thing and not another one, the answer to those questions is easy: “You can either write the application in C# or Java, both being probably equivalent in your case. Note that I'm a C# developer, so if you choose Java, I would not be able to work on your project and you would need to find another freelancer.” When you know both technologies, you can't answer that. In this case, how to explain to the customer that the question he asks is subject to flamewar and has no real consequences on his project? In other words, how to explain that you've chosen to use one technology rather than an equivalent one for the reasons related to human resources, without giving the impression to be unprofessional or to not care about the project? ¹ Example: Is MySQL better (worse?), performance-wise, compared to Oracle, for a personal website which will be accessed by, oh, let's be optimistic, two people per day? ² Example: for a given project, I was asked to asset if Windows Azure hosting would be cheaper than the hosting of the same application on a well-known ASP.NET hosting provider. The cost revealed to be exactly the same. ³ Example: your customer have an idea of a future application (the idea itself being extremely vague). There is no business plan, no requirements, nothing at all. Just an idea. You are asked if Java is better than C# for this app. What do you answer?

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  • How to explain bad software to non-technical people?

    - by mtutty
    In discussing software development with non-technical people (customers, business owners, project sponsors, etc.), I often resort to analogies and metaphors. It's relatively easy and effective to use a "house" or other metaphor for describing the size and complexity of new development. However, we often inherit someone else's code or data, and this approach doesn't seem to hold up as well when trying to explain why we're gutting something that already seems to work. Of course we can point to cycle time and cost to be saved in the future but this generally means nothing to business folks. I know doctors can say "just take this pill," but I'm not sure that software devs have the same authority. Ideas? EDIT: Let me add a bit to the discussion. The specific project I'm talking about has customers that don't realize (or care) about specific aspects of the system we're retiring (i.e., they think it was just fine): The system would save a NEW RECORD every time someone updated a field The system contained tables for reference data. These tables had new records added every day, even though they were duplicates of previous records. And there was no way to tie the reference data used for a particular case at the time it was closed. This is like 99% of the data in the old system. The field NAMES also have spaces, apostrophes and other inappropriate characters in them, making everything harder to work with. In addition to the incredible amount of duplicate data, they have around 1000 XLS files with data they want added to the system. Previously, they would do a spreadsheet for each case in the database, IN ADDITION TO what they typed into the database. Getting rid of this old, unneeded information and piping in the XLS data comprises about 80% of the total project effort, and was not something we could accurately predict. I'm trying to find a concrete way to describe how bad this thing was, mostly so that the customer will understand why the migration process has been so time-consuming. The actual coding was done pretty quickly and the new system works fine, but without the old data they won't be happy. Sorry to get into the weeds, but most of the answers I've seen so far are pretty basic scope/schedule/cost things. I've been doing this for 15 years, so this really is more of a reflective, philosophical question - but without some of the details it can be difficult to really appreciate the awful beauty of this problem.

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  • Powerful Lessons in Data from the Presidential Election

    - by Christina McKeon
    Now that we’ve had a few days to recover from the U.S. presidential election, it’s a good time to take a step back from politics and look for the customer experience lessons that we can take away. The most powerful lesson is that when you know more about your base, you will have an advantage over your competition. That advantage will translate into you winning and your competition losing. Michael Scherer of TIME was given access to Obama’s data analysts two days before the election. His account is documented in Inside the Secret World of the Data Crunchers Who Helped Obama Win. What we learned from Scherer’s inside view is how well Obama’s team did in getting the right data, analyzing it, and acting on it. This data team recognized how critical it was to break down data silos within the campaign. As Scherer noted, they created “a single system that merged information from pollsters, fundraisers, field workers, consumer databases, and social-media and mobile contacts with the main Democratic voter files in the swing states.” The Obama analysis was so meticulous that they knew which celebrity and which type of celebrity event would help them maximize campaign contributions. With a single system, their data models became more precise. They determined which messages were more successful with specific demographic groups and that who made the calls mattered. Data analysis also led to many other changes in Obama’s campaign including a new ad buying strategy, using social media and applications to tap into supporters’ friends, and using new social news sites. While we did not have that same inside view into Romney’s campaign, much of the post-mortem coverage indicates that Romney’s team did not have the right analysis. As Peter Hamby of CNN wrote in Analysis: Why Romney Lost, “Romney officials had modeled an electorate that looked something like a mix of 2004 and 2008….” That historical data did not account for the changing demographics in the U.S. Does your organization approach data like the Obama or Romney team? Do you really know your base? How well can you predict what is going to happen in your business? If you haven’t already put together a strategy and plan to know more, this week’s civics lesson is a powerful reason to do it sooner rather than later. Your competitors are probably thinking the same thing that you are!

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  • Are closures with side-effects considered "functional style"?

    - by Giorgio
    Many modern programming languages support some concept of closure, i.e. of a piece of code (a block or a function) that Can be treated as a value, and therefore stored in a variable, passed around to different parts of the code, be defined in one part of a program and invoked in a totally different part of the same program. Can capture variables from the context in which it is defined, and access them when it is later invoked (possibly in a totally different context). Here is an example of a closure written in Scala: def filterList(xs: List[Int], lowerBound: Int): List[Int] = xs.filter(x => x >= lowerBound) The function literal x => x >= lowerBound contains the free variable lowerBound, which is closed (bound) by the argument of the function filterList that has the same name. The closure is passed to the library method filter, which can invoke it repeatedly as a normal function. I have been reading a lot of questions and answers on this site and, as far as I understand, the term closure is often automatically associated with functional programming and functional programming style. The definition of function programming on wikipedia reads: In computer science, functional programming is a programming paradigm that treats computation as the evaluation of mathematical functions and avoids state and mutable data. It emphasizes the application of functions, in contrast to the imperative programming style, which emphasizes changes in state. and further on [...] in functional code, the output value of a function depends only on the arguments that are input to the function [...]. Eliminating side effects can make it much easier to understand and predict the behavior of a program, which is one of the key motivations for the development of functional programming. On the other hand, many closure constructs provided by programming languages allow a closure to capture non-local variables and change them when the closure is invoked, thus producing a side effect on the environment in which they were defined. In this case, closures implement the first idea of functional programming (functions are first-class entities that can be moved around like other values) but neglect the second idea (avoiding side-effects). Is this use of closures with side effects considered functional style or are closures considered a more general construct that can be used both for a functional and a non-functional programming style? Is there any literature on this topic? IMPORTANT NOTE I am not questioning the usefulness of side-effects or of having closures with side effects. Also, I am not interested in a discussion about the advantages / disadvantages of closures with or without side effects. I am only interested to know if using such closures is still considered functional style by the proponent of functional programming or if, on the contrary, their use is discouraged when using a functional style.

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  • Is IE9 a modern browser?

    - by anirudha
    Is IE9 a modern browser? i show you a post who compare IE as well as they compare chrome. Is IE9 a modern browser? well Are you thing that they make something bettter then thing another that what Firefox and chrome do whenever Microsoft do this. that's point that Microsoft always blast IE because they make version upon version not upon update like Firefox make 3.6.14 after 3.6.13 and chrome give update soon as possible but IE not come soon. they will thing for making 10 instead of giving update on 9. well what they tell us new. they make fool public everytime i believe they make fool public as same as today they maked for version 9 they show developer tool in 9 have three new tabs or pael are this enough. whenever  in chrome and firefox their is many plugin who make development easier IE still have a developer tool who not have enough power like Firebug in Firefox. they show performance but forget luna user [window xp] and their IE never runs on other plateform but chrome and firefox can. no customization in IE whenever chrome and firefox have uncountable plugin and addons. show features now in IE who already implemented in firefox very early. well their is no rule that static goes right every time not sure that IE and Firefox both are right in their language. their is no one predict what thing goes better in future. so well keep a thing in mind never wasted time and also thing to make task easier even you need to use sollution opensource or closesoure inside or outside MS does not matter. well everyone tell you much more then they do even IE and some other. they never tell you this thing not in IE but in another can be found they never tell you use other whenever you need a thing and never can be found in their software. you need to more beware of IE because they make them commorcial not really for public if really then why they stop wxp user to use them as well firefox and chrome never force. because they need a thing that force more then more copy of windows sale. so they thing to add a thing in window 8. the IE9 they thing to make before that they thing to make  this for windows 8. they always force user to purchase this for this. this for this. and this trick sell their software. well outside MS Mozilla and Chrome all behave better with user and their feedback. they respect user their privacy and feedback. if you not believe that how much problem you found in IE and they got solved soon as in chrome and firefox bug kill soon. because IE not opensource we need to  boycutt them secondly their is no customization then they make user task easier even with twitter and facebook.

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  • Best system for creating a 2d racing track

    - by tesselode
    I am working a 2D racing game and I'm trying to figure out what is the best way to define the track. At the very least, I need to be able to create a closed circuit with any amount of turns at any angle, and I need vehicles to collide with the edges of the track. I also want the following things to be true if possible (but they are optional): The code is simple and free of funky workarounds and extras I can define all of the parts of the track (such as turns) relative to the previous parts I can predict the exact position of the road at a certain point (that way I can easily and cleanly make closed circuits) Here are my options: Use a set of points. This is my current system. I have a set of turns and width changes that the track is supposed to make over time. I have a point which I transform according to these instructions, and I place a point every 5 steps or so, depending on how precise I want the track to be. These points make up the track. The main problem with this is the discrepancy between the collisions and the way the track is drawn. I won't get into too much detail, but the picture below shows what is happening (although it is exaggerated a bit). The blue lines are what is drawn, the red lines are what the vehicle collides with. I could work around this, but I'd rather avoid funky workaround code. Beizer curves. These seem cool, but my first impression of them is that they'll be a little daunting to learn and are probably too complicated for my needs. Some other kind of curve? I have heard of some other kinds of curves; maybe those are more applicable. Use Box2D or another physics engine. Instead of defining the center of the track, I could use a physics engine to define shapes that make up the road. The downside to this, however, is that I have to put in a little more work to place the checkpoints. Something completely different. Basically, what is the simplest system for generating a race track that would allow me to create closed circuits cleanly, handle collisions, and not have a ton of weird code?

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  • C Programming arrays, I dont understand how I would go about making this program, If anyone can just guide me through the basic outline please :) [on hold]

    - by Rashmi Kohli
    Problem The temperature of a car engine has been measured, from real-world experiments, as shown in the table and graph below: Time (min) Temperature (oC) 0 20 1 36 2 61 3 68 4 77 5 110 Use linear regression to find the engine’s temperature at 1.5 minutes, 4.3 minutes, and any other time specified by the user. Background In engineering, many times we measure several data points in an experiment, but then we need to predict a value that we have not measured which lies between two measured values, such as the problem statement above. If the relation between the measured parameters seems to be roughly linear, then we can use linear regression to find the relationship between those parameters. In the graph of the problem statement above, the relation seems to be roughly linear. Hence, we can apply linear regression to the above problem. Assuming y {y0, y1, …yn-1} has a linear relation with x {x0, x1, … xn-1}, we can say that: y = mx+b where m and b can be found with linear regression as follows: For the problem in this lab, using linear regression gives us the following line (in blue) compared to the measured curve (in red). As you can see, there is usually a difference between the measured values and the estimated (predicted) values. What linear regression does is to minimize those differences and still give us a straight line (blue). Other methods, such as non-linear regression, are also possible to achieve higher accuracy and better curve fitting. Requirements Your program should first print the table of the temperatures similar to the way it’s printed in the problem statement. It should then calculate the temperature at minute 1.5 and 4.3 and show the answers to the user. Next, it should prompt the user to enter a time in minutes (or -1 to quit), and after reading the user’s specified time it should give the value of the engine’s temperature at that time. It should then go back to the prompt. Hints •Use a one dimensional array to store the temperature values given in the problem statement. •Use functions to separate tasks such as calculating m, calculating b, calculating the temperature at a given time, printing the prompt, etc. You can then give your algorithm as well as you pseudo code per function, as opposed to one large algorithm diagram or one large sequence of pseudo code.

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  • managing a high traffic media sharing website

    - by Jordan Westerman
    i'm in the process of developing a website that i predict will generate a lot of traffic. the site will be similar to many other sites offering free media streaming: mp3's. we are going to start with a pretty minimal amount of media to share, but the basic idea is that artists will set up a profile page with music they have made available for consumers to visit the page and listen to the music. we are starting with just a handful of artists, but i think that this project will generate more and more artist pages. eventually i'd like to set it up so consumers can create personalized playlists. how can i best prepare server space and bandwidth capabilities? i have a small team of web designers and programmers working on the site, as i am pretty illiterate when it comes to site management. as the ring leader of this organization, i am more or less looking for financial requirements and monthly burn rate estimates. i don't have a ton of capitol to start with, putting together a business plan, but i am seeking investments. i have a game plan to grow fast enough to be successful, and slow enough to manage the financial growth requirements. any questions i may have failed to ask myself? is it realistic to start this project on a shared server, and upgrade? any financial advice you think i can use? i really appreciate any advice given, as this is my first business venture. thank you all in advance. Jordan Westerman D.B.A. Badfish Productions, LLC

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  • calculate AUC (GAM) in R [migrated]

    - by ahmad
    I used the following script to calculate AUC in R: library(mgcv) library(ROCR) library(AUC) data1=read.table("d:\\2005.txt", header=T) GAM<-gam(tuna ~ s(chla)+s(sst)+s(ssha),family=binomial, data=data1) gampred<- predict(GAM, type="response") rp <- prediction(gampred, data1$tuna) auc <- performance( rp, "auc")@y.values[[1]] auc roc <- performance( rp, "tpr", "fpr") plot( roc ) But when I was running the script, the result is: **rp <- prediction(gampred, data1$tuna) Error in prediction(gampred, data1$tuna) : Format of predictions is invalid. > > auc <- performance( rp, "auc")@y.values[[1]] Error in performance(rp, "auc") : object 'rp' not found > auc function (x, min = 0, max = 1) { if (any(class(x) == "roc")) { if (min != 0 || max != 1) { x$fpr <- x$fpr[x$cutoffs >= min & x$cutoffs <= max] x$tpr <- x$tpr[x$cutoffs >= min & x$cutoffs <= max] } ans <- 0 for (i in 2:length(x$fpr)) { ans <- ans + 0.5 * abs(x$fpr[i] - x$fpr[i - 1]) * (x$tpr[i] + x$tpr[i - 1]) } } else if (any(class(x) %in% c("accuracy", "sensitivity", "specificity"))) { if (min != 0 || max != 1) { x$cutoffs <- x$cutoffs[x$cutoffs >= min & x$cutoffs <= max] x$measure <- x$measure[x$cutoffs >= min & x$cutoffs <= max] } ans <- 0 for (i in 2:(length(x$cutoffs))) { ans <- ans + 0.5 * abs(x$cutoffs[i - 1] - x$cutoffs[i]) * (x$measure[i] + x$measure[i - 1]) } } return(as.numeric(ans)) } <bytecode: 0x03012f10> <environment: namespace:AUC> > > roc <- performance( rp, "tpr", "fpr") Error in performance(rp, "tpr", "fpr") : object 'rp' not found > plot( roc ) Error in levels(labels) : argument "labels" is missing, with no default** Can anybody help me to solve this problem? Thank you in advance.

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  • Difficult to point-and-click target with Apple Magic Trackpad?

    - by Andrew Swift
    My Magic Trackpad is great for most things involving dragging and gestures, but for simple point-and-click use it is starting to get really annoying. For example, my bank has a numeric code that I need to enter from a visual grid on the screen, by clicking on the six numbers in order. To do this is quite difficult with the Magic Trackpad. Idea 1: it is because when you start dragging on the touchpad, there is a brief delay before the mouse starts to move. The delay might be enough to screw up my anticipation of where the cursor is going to go. Idea 2: it may have to do with the cursor acceleration. If I move it a little, the cursor moves a little. If I move it a lot, it goes much faster. I have tried various settings in the preference pane, and although the cursor does move more or less quickly, it doesn't seem any more or less easy to hit a given target. As I am writing this post, I tried a brief experiment -- I chose a spot on the page (the bracket in the superuser logo) and tried to move the cursor there in one quick movement. It's extremely difficult, even though I've been using Macs and touchpads since 1999. There is something about the behavior of the trackpad that is making it impossible for me to learn how to accurately predict where the cursor will end up. Does anyone else have this problem?

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  • Difficult to point-and-click target with Apple Magic Trackpad?

    - by Andrew Swift
    My Magic Trackpad is great for most things involving dragging and gestures, but for simple point-and-click use it is starting to get really annoying. For example, my bank has a numeric code that I need to enter from a visual grid on the screen, by clicking on the six numbers in order. To do this is quite difficult with the Magic Trackpad. Idea 1: it is because when you start dragging on the touchpad, there is a brief delay before the mouse starts to move. The delay might be enough to screw up my anticipation of where the cursor is going to go. Idea 2: it may have to do with the cursor acceleration. If I move it a little, the cursor moves a little. If I move it a lot, it goes much faster. I have tried various settings in the preference pane, and although the cursor does move more or less quickly, it doesn't seem any more or less easy to hit a given target. As I am writing this post, I tried a brief experiment -- I chose a spot on the page (the bracket in the superuser logo) and tried to move the cursor there in one quick movement. It's extremely difficult, even though I've been using Macs and touchpads since 1999. There is something about the behavior of the trackpad that is making it impossible for me to learn how to accurately predict where the cursor will end up. Does anyone else have this problem?

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  • Looking for issue tracker software for residential property management

    - by Rob
    This question is about a computer software (as per SU guidelines) application for centrally tracking issues concerning the management of a residental block of flats (apartments as they say in the US and France). Issues are incidents - and their resultant unplanned maintenance to address them, also planned one-off maintenance and also regular planned routine maintenance. I live in a block of flats (apartments), and along with other residents, are looking to more closely watch over issues with the communal, shared areas of the premises (corridors, courtyards, stairs, lifts, lights, trash/bin shed, bike stands, parking areas etc) and their maintenance, currently done by a property management company. Our own homes are our own affair internally, its the outside communal areas that I have the interest. The aim being to control costs and possibly reduce them, by proactively managing the property using historical data to predict issues and also to scrutinise maintenance charges against such data to ensure that the costs are as expected. Trending could also be established whereby recurrences of things can be detected and pre-empted to reduce costs. As a software professional, I'm aware of Bugzilla, eventum being free tools for software - which could be customised to fit this application, but wondered if there was something more appropriate. It might be useful for such software to be on a web server, with secure access, so that residents can log in and view the issues.

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  • file system that allow to specify different RAID level per directory and change it afterward

    - by Adam Ryczkowski
    I have 5 hard drives, where I want to keep my data. Some of my files are more important, and some of them are less. So some of them I wish to put on RAID-6, and for some it RAID-5 is sufficient. It is difficult to predict at the moment of creation of the arrays how much space of each type to declare. What I would do if I didn't hear about zfs, is partition the hard drives into identical 100GB partitions, and as my needs grow, assemble those partitions into md devices using linux-raid. Then, I'd combine those devices using lvm into logical volumes where I'd put my data. So when I'd need more space of e.g. RAID-6, I'd take 100GB partition from each hard drive and assemble them into another RAID-6 md device and would use it as physical storage for the logical volume group dedicated for RAID-6 data. Then I could grow the file system on this logical volume. On top of RAID-6 and RAID-5 Volume Groups (managed by lvm) would reside completely independent file systems, which I'd later merge with multiple mount --bind into a single directory structure that would reflect the logical structure of data rather that of the storage. But now, when I heard about the ZFS with all the performance, data-healing and compression capabilities I cannot stop thinking if it can help me. If so, what do you think would be the best setup?

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  • Oracle Fusion Procurement Designed for User Productivity

    - by Applications User Experience
    Sean Rice, Manager, Applications User Experience Oracle Fusion Procurement Design Goals In Oracle Fusion Procurement, we set out to create a streamlined user experience based on the way users do their jobs. Oracle has spent hundreds of hours with customers to get to the heart of what users need to do their jobs. By designing a procurement application around user needs, Oracle has crafted a user experience that puts the tools that people need at their fingertips. In Oracle Fusion Procurement, the user experience is designed to provide the user with information that will drive navigation rather than requiring the user to find information. One of our design goals for Oracle Fusion Procurement was to reduce the number of screens and clicks that a user must go through to complete frequently performed tasks. The requisition process in Oracle Fusion Procurement (Figure 1) illustrates how we have streamlined workflows. Oracle Fusion Self-Service Procurement brings together billing metrics, descriptions of the order, justification for the order, a breakdown of the components of the order, and the amount—all in one place. Previous generations of procurement software required the user to navigate to several different pages to gather all of this information. With Oracle Fusion, everything is presented on one page. The result is that users can complete their tasks in less time. The focus is on completing the work, not finding the work. Figure 1. Creating a requisition in Oracle Fusion Self-Service Procurement is a consumer-like shopping experience. Will Oracle Fusion Procurement Increase Productivity? To answer this question, Oracle sought to model how two experts working head to head—one in an existing enterprise application and another in Oracle Fusion Procurement—would perform the same task. We compared Oracle Fusion designs to corresponding existing applications using the keystroke-level modeling (KLM) method. This method is based on years of research at universities such as Carnegie Mellon and research labs like Xerox Palo Alto Research Center. The KLM method breaks tasks into a sequence of operations and uses standardized models to evaluate all of the physical and cognitive actions that a person must take to complete a task: what a user would have to click, how long each click would take (not only the physical action of the click or typing of a letter, but also how long someone would have to think about the page when taking the action), and user interface changes that result from the click. By applying standard time estimates for all of the operators in the task, an estimate of the overall task time is calculated. Task times from the model enable researchers to predict end-user productivity. For the study, we focused on modeling procurement business process task flows that were considered business or mission critical: high-frequency tasks and high-value tasks. The designs evaluated encompassed tasks that are currently performed by employees, professional buyers, suppliers, and sourcing professionals in advanced procurement applications. For each of these flows, we created detailed task scenarios that provided the context for each task, conducted task walk-throughs in both the Oracle Fusion design and the existing application, analyzed and documented the steps and actions required to complete each task, and applied standard time estimates to the operators in each task to estimate overall task completion times. The Results The KLM method predicted that the Oracle Fusion Procurement designs would result in productivity gains in each task, ranging from 13 percent to 38 percent, with an overall productivity gain of 22.5 percent. These performance gains can be attributed to a reduction in the number of clicks and screens needed to complete the tasks. For example, creating a requisition in Oracle Fusion Procurement takes a user through only two screens, while ordering the same item in a previous version requires six screens to complete the task. Modeling user productivity has resulted not only in advances in Oracle Fusion applications, but also in advances in other areas. We leveraged lessons learned from the KLM studies to establish products like Oracle E-Business Suite (EBS). New user experience features in EBS 12.1.3, such as navigational improvements to the main menu, a Google-type search using auto-suggest, embedded analytics, and an in-context list of values tool help to reduce clicks and improve efficiency. For more information about KLM, refer to the Measuring User Productivity blog.

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  • To sample or not to sample...

    - by [email protected]
    Ideally, we would know the exact answer to every question. How many people support presidential candidate A vs. B? How many people suffer from H1N1 in a given state? Does this batch of manufactured widgets have any defective parts? Knowing exact answers is expensive in terms of time and money and, in most cases, is impractical if not impossible. Consider asking every person in a region for their candidate preference, testing every person with flu symptoms for H1N1 (assuming every person reported when they had flu symptoms), or destructively testing widgets to determine if they are "good" (leaving no product to sell). Knowing exact answers, fortunately, isn't necessary or even useful in many situations. Understanding the direction of a trend or statistically significant results may be sufficient to answer the underlying question: who is likely to win the election, have we likely reached a critical threshold for flu, or is this batch of widgets good enough to ship? Statistics help us to answer these questions with a certain degree of confidence. This focuses on how we collect data. In data mining, we focus on the use of data, that is data that has already been collected. In some cases, we may have all the data (all purchases made by all customers), in others the data may have been collected using sampling (voters, their demographics and candidate choice). Building data mining models on all of your data can be expensive in terms of time and hardware resources. Consider a company with 40 million customers. Do we need to mine all 40 million customers to get useful data mining models? The quality of models built on all data may be no better than models built on a relatively small sample. Determining how much is a reasonable amount of data involves experimentation. When starting the model building process on large datasets, it is often more efficient to begin with a small sample, perhaps 1000 - 10,000 cases (records) depending on the algorithm, source data, and hardware. This allows you to see quickly what issues might arise with choice of algorithm, algorithm settings, data quality, and need for further data preparation. Instead of waiting for a model on a large dataset to build only to find that the results don't meet expectations, once you are satisfied with the results on the initial sample, you can  take a larger sample to see if model quality improves, and to get a sense of how the algorithm scales to the particular dataset. If model accuracy or quality continues to improve, consider increasing the sample size. Sampling in data mining is also used to produce a held-aside or test dataset for assessing classification and regression model accuracy. Here, we reserve some of the build data (data that includes known target values) to be used for an honest estimate of model error using data the model has not seen before. This sampling transformation is often called a split because the build data is split into two randomly selected sets, often with 60% of the records being used for model building and 40% for testing. Sampling must be performed with care, as it can adversely affect model quality and usability. Even a truly random sample doesn't guarantee that all values are represented in a given attribute. This is particularly troublesome when the attribute with omitted values is the target. A predictive model that has not seen any examples for a particular target value can never predict that target value! For other attributes, values may consist of a single value (a constant attribute) or all unique values (an identifier attribute), each of which may be excluded during mining. Values from categorical predictor attributes that didn't appear in the training data are not used when testing or scoring datasets. In subsequent posts, we'll talk about three sampling techniques using Oracle Database: simple random sampling without replacement, stratified sampling, and simple random sampling with replacement.

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