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• Creating a timetable using PHP

  - by Big Sal

  I am going to create a little app using PHP that acts as a timetable. I am going to have it going from 9.00am to 5.00pm and through monday to friday. I am still deciding how i want the timetable to function but have this idea though, the user mouses over a section of the timetable, when the user clicks that point, a new event booking window opens up and the user selects the event type and event duration and then saves. Now, I was going to create a 1440 pixel wide table and then have have each hour have 180pixels and each minute of that hour taking up 3 pixels. How would you go about implementing such a thing, and by that i mean, how would you go about making the app so that it knows what time it is when a user clicks a certain portion of the timetable? Im not asking for code or anything like that, I'm just wondering how more experienced developers would go about creating such a timetable because there are a few other ways i have thought about going about this problem but its always nice to hear other peoples ideas about how they would go about solving a problem. Any ideas are welcomed, Thanks.

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• Project Euler considered harmful

  - by xxxxxxx

  Hi, I've done some Project Euler problems and I was able to solve them very fast because I already knew all the theory behind them. I learned that "accidentaly" because I also had to learn it for university. I used to also solve olympiad problems, I wasn't very good but I was solving some of the problems. I've reached the conclusion that Project Euler problems are taken out of their context(and olympiad problems as well). That's why they are hard. Mathematics and it's theory is taught in order to make the problems easy. However, Project Euler apparently makes an invitation at making them hard again. Why ? I honestly think this is a complete waste of time. Mathematicians had centuries at their disposal in order to solve math problems and they developed theories to explain properly why certain things happen. I think olympiad problems and Project Euler problems are really useless. What's your take on Project Euler ? Do you get something out of it or do you just find formulas on some websites and implement the code fast and then get the result and solve the problem ?

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• Spam proof hit counter in Django

  - by Jim Robert

  I already looked at the most popular Django hit counter solutions and none of them seem to solve the issue of spamming the refresh button. Do I really have to log the IP of every visitor to keep them from artificially boosting page view counts by spamming the refresh button (or writing a quick and dirty script to do it for them)? More information So right now you can inflate your view count with the following few lines of Python code. Which is so little that you don't even really need to write a script, you could just type it into an interactive session: from urllib import urlopen num_of_times_to_hit_page = 100 url_of_the_page = "http://example.com" for x in range(num_of_times_to_hit_page): urlopen(url_of_the_page) Solution I'll probably use To me, it's a pretty rough situation when you need to do a bunch of writes to the database on EVERY page view, but I guess it can't be helped. I'm going to implement IP logging due to several users artificially inflating their view count. It's not that they're bad people or even bad users. See the answer about solving the problem with caching... I'm going to pursue that route first. Will update with results. For what it's worth, it seems Stack Overflow is using cookies (I can't increment my own view count, but it increased when I visited the site in another browser.) I think that the benefit is just too much, and this sort of 'cheating' is just too easy right now. Thanks for the help everyone!

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• Is any solution the correct solution?

  - by Eli

  I always think to myself after solving a programming challenge that I have been tied up with for some time, "It works, thats good enough". I don't think this is really the correct mindset, in my opinion and I think I should always be trying to code with the greatest performance. Anyway, with this said, I just tried a ProjectEuler question. Specifically question #2. How could I have improved this solution. I feel like its really verbose. Like I'm passing the previous number in recursion. <?php /* Each new term in the Fibonacci sequence is generated by adding the previous two terms. By starting with 1 and 2, the first 10 terms will be: 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, ... Find the sum of all the even-valued terms in the sequence which do not exceed four million. */ function fibonacci ( $number, $previous = 1 ) { global $answer; $fibonacci = $number + $previous; if($fibonacci > 4000000) return; if($fibonacci % 2 == 0) { $answer = is_numeric($answer) ? $answer + $fibonacci : $fibonacci; } return fibonacci($fibonacci, $number); } fibonacci(1); echo $answer; ?> Note this isn't homework. I left school hundreds of years ago. I am just feeling bored and going through the Project Euler questions

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• Why does Raphael's framerate slow down on this code?

  - by Bob

  So I'm just doing a basic orbit simulator using Raphael JS, where I draw one circle as the "star" and another circle as the "planet". It seems to be working just fine, with the one snag that as the simulation continues, its framerate progressively slows down until the orbital motion no longer appears fluid. Here's the code (note: uses jQuery only to initialize the page): $(function() { var paper = Raphael(document.getElementById('canvas'), 640, 480); var star = paper.circle(320, 240, 10); var planet = paper.circle(320, 150, 5); var starVelocity = [0,0]; var planetVelocity = [20.42,0]; var starMass = 3.08e22; var planetMass = 3.303e26; var gravConstant = 1.034e-18; function calculateOrbit() { var accx = 0; var accy = 0; accx = (gravConstant * starMass * ((star.attr('cx') - planet.attr('cx')))) / (Math.pow(circleDistance(), 3)); accy = (gravConstant * starMass * ((star.attr('cy') - planet.attr('cy')))) / (Math.pow(circleDistance(), 3)); planetVelocity[0] += accx; planetVelocity[1] += accy; planet.animate({cx: planet.attr('cx') + planetVelocity[0], cy: planet.attr('cy') + planetVelocity[1]}, 150, calculateOrbit); paper.circle(planet.attr('cx'), planet.attr('cy'), 1); // added to 'trace' orbit } function circleDistance() { return (Math.sqrt(Math.pow(star.attr('cx') - planet.attr('cx'), 2) + Math.pow(star.attr('cy') - planet.attr('cy'), 2))); } calculateOrbit(); }); It doesn't appear, to me anyway, that any part of that code would cause the animation to gradually slow down to a crawl, so any help solving the problem will be appreciated!

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• The woes of (sometimes) storing "date only" in datetimes

  - by Heinzi

  We have two fields from and to (of type datetime), where the user can store the begin time and the end time of a business trip, e.g.: From: 2010-04-14 09:00 To: 2010-04-16 16:30 So, the duration of the trip is 2 days and 7.5 hours. Often, the exact times are not known in advance, so the user enters the dates without a time: From: 2010-04-14 To: 2010-04-16 Internally, this is stored as 2010-04-14 00:00 and 2010-04-16 00:00, since that's what most modern class libraries (e.g. .net) and databases (e.g. SQL Server) do when you store a "date only" in a datetime structure. Usually, this makes perfect sense. However, when entering 2010-04-16 as the to date, the user clearly did not mean 2010-04-16 00:00. Instead, the user meant 2010-04-16 24:00, i.e., calculating the duration of the trip should output 3 days, not 2 days. I can think of a few (more or less ugly) workarounds for this problem (add "23:59" in the UI layer of the to field if the user did not enter a time component; add a special "dates are full days" Boolean field; store "2010-04-17 00:00" in the DB but display "2010-04-16 24:00" to the user if the time component is "00:00"; ...), all having advantages and disadvantages. Since I assume that this is a fairly common problem, I was wondering: Is there a "standard" best-practice way of solving it? If there isn't, have you experienced a similar requirement, how did you solve it and what were the pros/cons of that solution?

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• Beginner problems with references to arrays in python 3.1.1

  - by Protean

  As part of the last assignment in a beginner python programing class, I have been assigned a traveling sales man problem. I settled on a recursive function to find each permutation and the sum of the distances between the destinations, however, I am have a lot of problems with references. Arrays in different instances of the Permute and Main functions of TSP seem to be pointing to the same reference. from math import sqrt class TSP: def __init__(self): self.CartisianCoordinates = [['A',[1,1]], ['B',[2,2]], ['C',[2,1]], ['D',[1,2]], ['E',[3,3]]] self.Array = [] self.Max = 0 self.StoredList = ['',0] def Distance(self, i1, i2): x1 = self.CartisianCoordinates[i1][1][0] y1 = self.CartisianCoordinates[i1][1][1] x2 = self.CartisianCoordinates[i2][1][0] y2 = self.CartisianCoordinates[i2][1][1] return sqrt(pow((x2 - x1), 2) + pow((y2 - y1), 2)) def Evaluate(self): temparray = [] Data = [] for i in range(len(self.CartisianCoordinates)): Data.append([]) for i1 in range(len(self.CartisianCoordinates)): for i2 in range(len(self.CartisianCoordinates)): if i1 != i2: temparray.append(self.Distance(i1, i2)) else: temparray.append('X') Data[i1] = temparray temparray = [] self.Array = Data self.Max = len(Data) def Permute(self,varray,index,vcarry,mcarry): #Problem Class array = varray[:] carry = vcarry[:] for i in range(self.Max): print ('ARRAY:', array) print (index,i,carry,array[index][i]) if array[index][i] != 'X': carry[0] += self.CartisianCoordinates[i][0] carry[1] += array[index][i] if len(carry) != self.Max: temparray = array[:] for j in range(self.Max):temparray[j][i] = 'X' index = i mcarry += self.Permute(temparray,index,carry,mcarry) else: return mcarry print ('pass',mcarry) return mcarry def Main(self): out = [] self.Evaluate() for i in range(self.Max): array = self.Array[:] #array appears to maintain the same reference after each copy, resulting in an incorrect array being passed to Permute after the first iteration. print (self.Array[:]) for j in range(self.Max):array[j][i] = 'X' print('I:', i, array) out.append(self.Permute(array,i,[str(self.CartisianCoordinates[i][0]),0],[])) return out SalesPerson = TSP() print(SalesPerson.Main()) It would be greatly appreciated if you could provide me with help in solving the reference problems I am having. Thank you.

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• Pros & Cons of Google App Engine

  - by Rishi

  Pros & Cons of Google App Engine [An Updated List 21st Aug 09] Help me Compile a List of all the Advantages & Disadvantages of Building an Application on the Google App Engine Pros: 1) No Need to buy Servers or Server Space (no maintenance). 2) Makes solving the problem of scaling much easier. Cons: 1) Locked into Google App Engine ?? 2)Developers have read-only access to the filesystem on App Engine. 3)App Engine can only execute code called from an HTTP request (except for scheduled background tasks). 4)Users may upload arbitrary Python modules, but only if they are pure-Python; C and Pyrex modules are not supported. 5)App Engine limits the maximum rows returned from an entity get to 1000 rows per Datastore call. 6)Java applications may only use a subset (The JRE Class White List) of the classes from the JRE standard edition. 7)Java applications cannot create new threads. Known Issues!! http://code.google.com/p/googleappengine/issues/list Hard limits Apps per developer - 10 Time per request - 30 sec Files per app - 3,000 HTTP response size - 10 MB Datastore item size - 1 MB Application code size - 150 MB Pro or Con? App Engine's infrastructure removes many of the system administration and development challenges of building applications to scale to millions of hits. Google handles deploying code to a cluster, monitoring, failover, and launching application instances as necessary. While other services let users install and configure nearly any *NIX compatible software, App Engine requires developers to use Python or Java as the programming language and a limited set of APIs. Current APIs allow storing and retrieving data from a BigTable non-relational database; making HTTP requests; sending e-mail; manipulating images; and caching. Most existing Web applications can't run on App Engine without modification, because they require a relational database.

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• Finding distance to the closest point in a point cloud on an uniform grid

  - by erik

  I have a 3D grid of size AxBxC with equal distance, d, between the points in the grid. Given a number of points, what is the best way of finding the distance to the closest point for each grid point (Every grid point should contain the distance to the closest point in the point cloud) given the assumptions below? Assume that A, B and C are quite big in relation to d, giving a grid of maybe 500x500x500 and that there will be around 1 million points. Also assume that if the distance to the nearest point exceds a distance of D, we do not care about the nearest point distance, and it can safely be set to some large number (D is maybe 2 to 10 times d) Since there will be a great number of grid points and points to search from, a simple exhaustive: for each grid point: for each point: if distance between points < minDistance: minDistance = distance between points is not a good alternative. I was thinking of doing something along the lines of: create a container of size A*B*C where each element holds a container of points for each point: define indexX = round((point position x - grid min position x)/d) // same for y and z add the point to the correct index of the container for each grid point: search the container of that grid point and find the closest point if no points in container and D > 0.5d: search the 26 container indices nearest to the grid point for a closest point .. continue with next layer until a point is found or the distance to that layer is greater than D Basically: put the points in buckets and do a radial search outwards until a points is found for each grid point. Is this a good way of solving the problem, or are there better/faster ways? A solution which is good for parallelisation is preferred.

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• Kohana 3, themes outside application.

  - by Marek

  Hi all I read http://forum.kohanaframework.org/comments.php?DiscussionID=5744&page=1#Item_0 and I want to use similar solution, but with db. In my site controller after(): $theme = $page->get_theme_name(); //Orange Kohana::set_module_path('themes', Kohana::get_module_path('themes').'/'.$theme); $this->template = View::factory('layout') I checked with firebug: fire::log(Kohana::get_module_path('themes')); // D:\tools\xampp\htdocs\kohana\themes/Orange I am sure that path exists. I have directly in 'Orange' folder 'views' folder with layout.php file. But I am getting: The requested view layout could not be found Extended Kohana_Core is just: public static function get_module_path($module_key) { return self::$_modules[$module_key]; } public static function set_module_path($module_key, $path) { self::$_modules[$module_key] = $path; } Could anybody help me with solving that issue? Maybe it is a .htaccess problem: # Turn on URL rewriting RewriteEngine On # Put your installation directory here: # If your URL is www.example.com/kohana/, use /kohana/ # If your URL is www.example.com/, use / RewriteBase /kohana/ # Protect application and system files from being viewed RewriteCond $1 ^(application|system|modules) # Rewrite to index.php/access_denied/URL RewriteRule ^(.*)$ / [PT,L] RewriteRule ^(media) - [PT,L] RewriteRule ^(themes) - [PT,L] # Allow these directories and files to be displayed directly: # - index.php (DO NOT FORGET THIS!) # - robots.txt # - favicon.ico # - Any file inside of the images/, js/, or css/ directories RewriteCond $1 ^(index\.php|robots\.txt|favicon\.ico|static) # No rewriting RewriteRule ^(.*)$ - [PT,L] # Rewrite all other URLs to index.php/URL RewriteRule ^(.*)$ index.php/$1 [PT,L] Could somebody help? What I am doing wrong? Regards

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• Connecting repeatable and non-repeatble backgrounds without a seam

  - by Stiggler

  I have a 700x300 background repeating seamlessly inside of the main content-div. Now I'd like to attach a div at the bottom of the content-div, containing a different background image that isn't repeatable, connecting seamlessly with the repeatable background above it. Essentially, the non-repeatable image will look like the end piece of the repeatable image. Due to the nature of the pattern, unless the full 300px height of the background image is visible in the last repeat of the content-div's backround, the background in the div below won't seamlessly connect. Basically, I need the content div's height to be a multiple of 300px under all circumstances. What's a good approach to this sort of problem? I've tried resizing the content-div on loading the page, but this only works as long as the content div doesn't contain any resizing, dynamic content, which is not my case: function adjustContentHeight() { // Setting content div's height to nearest upper multiple of column backgrounds height, // forcing it not to be cut-off when repeated. var contentBgHeight = 300; var contentHeight = $("#content").height(); var adjustedHeight = Math.ceil(contentHeight / contentBgHeight); $("#content").height(adjustedHeight * contentBgHeight); } $(document).ready(adjustContentHeight); What I'm looking for there is a way to respond to a div resizing event, but there doesn't seem to be such a thing. Also, please assume I have no access to the JS controlling the resizing of content in the content-div, though this is potentially a way of solving the problem. Another potential solution I was thinking off was to offset the background image in the bottom div by a certain amount depending on the height of the content-div. Again, the missing piece seems to be the ability to respond to a resize event.

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• SQL Query - group by more than one column, but distinct

  - by Ranhiru

  I have a bidding table, as follows: SellID INT FOREIGN KEY REFERENCES SellItem(SellID), CusID INT FOREIGN KEY REFERENCES Customer(CusID), Amount FLOAT NOT NULL, BidTime DATETIME DEFAULT getdate() Now in my website I need to show the user the current bids; only the highest bid but without repeating the same user. SELECT CusID, Max(Amount) FROM Bid WHERE SellID = 10 GROUP BY CusID ORDER BY Max(Amount) DESC This is the best I have achieved so far. This gives the CusID of each user with the maximum bid and it is ordered ascending. But I need to get the BidTime for each result as well. When I try to put the BidTime in to the query: SELECT CusID, Max(Amount), BidTime FROM Bid WHERE SellID = 10 GROUP BY CusID ORDER BY Max(Amount) DESC I am told that "Column 'Bid.BidTime' is invalid in the select list because it is not contained in either an aggregate function or the GROUP BY clause." Thus I tried: SELECT CusID, Max(Amount), BidTime FROM Bid WHERE SellID = 10 GROUP BY CusID, BidTime ORDER BY Max(Amount) DESC But this returns all the rows. No distinction. Any suggestions on solving this issue?

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• Getting error while connecting to facebook

  - by Bakhtiyor

  I have downloaded php-sdk for using facebook in php. I also created facebook application in the facebook web page in order to get API key and secret key. When I run example.php and try to connect to facebook it shows me the following error: Configuration errors: To fix this error, please set your Connect URL in the application settings editor. Once it has been set, users will be redirected to that URL instead of this page after logging in. I am using this php-sdk in the localhost. I tried to assign localhost as Connect URL but facebook doesn't accept it. I have read about Cross Domain Communication Channel and think this is what I need. But I don't know how to use it. Anyone can help me to solve this problem please? Update Actually what I need is following. I have Web Application and need to connect to facebook and search for users in facebook who has specific(user will specify this) Likes and Interests. Any idea about solving my problem?

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• Best pratice: How do I implement a list that can be rendered both server-side and client-side?

  - by André Pena

  Technologies involved: ASP.NET Web-forms Javascript (jQuery for instance) Case To make it clearer let's give the Stackoverflow authors list as an example. This list can be manipulated at client-side. I can search, page and so forth. So obviously we would need to call jQuery.ajax to retrieve the HTML of each page given a search. Alright. Now this leaves me with the first question: What is the best way to render the response for the jQuery.ajax at server-side? I can't use templates I suppose, so the most obvious solution I think is to create the HTML tags as server-controls and render them as the result of an ASHX request? Is this is best approach? Nice. That solved we have yet another problem: When the user first enters the Authors List the first list page should already come from the server completely rendered alright? Of course we could render the first page as well as an ajax call but I don't think it's better. This time I CAN use templates to render the list but this template couldn't be reused in case 1. What do I do? Now the final question: Now we have 2 rendering strategies: 1) Client and 2) Server. How do I reuse code for the 2 renderings? What are the best pratices for solving these problems?

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• I get an Exception when trying to implement reset password with Authlogic

  - by Tam

  Hi, I'm using Ruby on Rails 2.3.5 and Ruby 1.9 and implmeneted Authlogic as my authentication engine. Authlogic works fine. But now I have been trying to implement password reset using the following tutorial: http://www.binarylogic.com/2008/11/16/tutorial-reset-passwords-with-authlogic/ But I'm getting the following exception when I type mysite.com/password_resets/new Processing PasswordResetsController#new (for 127.0.0.1 at 2010-03-13 01:09:45) [GET] Completed in 9ms (DB: 0) | 200 [http://localhost/password_resets/new] [2010-03-13 01:09:45] ERROR TypeError: can't convert Array into String /Users/tammam56/.rvm/gems/ruby-1.9.1-p378/gems/activesupport-2.3.5/lib/active_support/core_ext/string/output_safety.rb:34:in `concat' /Users/tammam56/.rvm/gems/ruby-1.9.1-p378/gems/activesupport-2.3.5/lib/active_support/core_ext/string/output_safety.rb:34:in `concat_with_safety' /Users/tammam56/.rvm/gems/ruby-1.9.1-p378/gems/rack-1.0.1/lib/rack/handler/webrick.rb:63:in `block in service' /Users/tammam56/.rvm/gems/ruby-1.9.1-p378/gems/actionpack-2.3.5/lib/action_controller/response.rb:158:in `each' /Users/tammam56/.rvm/gems/ruby-1.9.1-p378/gems/actionpack-2.3.5/lib/action_controller/response.rb:158:in `each' /Users/tammam56/.rvm/gems/ruby-1.9.1-p378/gems/actionpack-2.3.5/lib/action_controller/string_coercion.rb:16:in `send' /Users/tammam56/.rvm/gems/ruby-1.9.1-p378/gems/actionpack-2.3.5/lib/action_controller/string_coercion.rb:16:in `method_missing' /Users/tammam56/.rvm/gems/ruby-1.9.1-p378/gems/actionpack-2.3.5/lib/action_controller/reloader.rb:22:in `method_missing' /Users/tammam56/.rvm/gems/ruby-1.9.1-p378/gems/rack-1.0.1/lib/rack/handler/webrick.rb:62:in `service' /Users/tammam56/.rvm/rubies/ruby-1.9.1-p378/lib/ruby/1.9.1/webrick/httpserver.rb:111:in `service' /Users/tammam56/.rvm/rubies/ruby-1.9.1-p378/lib/ruby/1.9.1/webrick/httpserver.rb:70:in `run' /Users/tammam56/.rvm/rubies/ruby-1.9.1-p378/lib/ruby/1.9.1/webrick/server.rb:183:in `block in start_thread' Honestly I'm not sure where to start debugging for this. Is it because I'm using Ruby 1.9? some people seem to be having trouble with Authlogic and Ruby 1.9: http://isitruby19.com/authlogic Please advise me how to go about solving/debugging this issues? Thanks, Tam

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• Best pratice: How do I implement a list similar to Stackoverflow's Users List?

  - by André Pena

  Technologies involved: ASP.NET Web-forms Javascript (jQuery for instance) Case To make it clearer let's give the Stackoverflow Users list as an example. This list can be manipulated at client-side. I can search, page and so forth. So obviously we would need to call jQuery.ajax to retrieve the HTML of each page given a search. Alright. Now this leaves me with the first question: What is the best way to render the response for the jQuery.ajax at server-side? I can't use templates I suppose, so the most obvious solution I think is to create the HTML tags as server-controls and render them as the result of an ASHX request? Is this is best approach? Nice. That solved we have yet another problem: When the user first enters the Authors List the first list page should already come from the server completely rendered alright? Of course we could render the first page as well as an ajax call but I don't think it's better. This time I CAN use templates to render the list but this template couldn't be reused in case 1. What do I do? Now the final question: Now we have 2 rendering strategies: 1) Client and 2) Server. How do I reuse code for the 2 renderings? What are the best pratices for solving these problems?

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• Google Code Jam 2010 Large DataSets Take Too Long to Submit

  - by Travis

  Hey Guys, I'm participating in the 2010 code jam and I solved two of the problems for the small data sets, but I'm not even close to solving the large data sets in the 8 minute time frame. I'm wondering if anyone out there has solved the large data set: What hardware were you running on? What language were you running on? What performance tuning techniques did you do on your code to run as fast as possible? I'm writing the solutions in Ruby, which is not my day to day language, and executing them on my Macbook Pro. My solutions for problem A and problem C are on github at http://github.com/tjboudreaux/codejam2010. I'd appreciate any suggestions that you may have. FWIW, I have alot of experience in C++ from college, my primary language is PHP, and my "sandbox" language is Ruby. Was I just a bit ambitious by taking a shot at this in Ruby, not knowing where the language struggles for performance, or does anyone see anything that's a redflag as to why I can't complete the large dataset in time to submit.

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• How do you think while formulating Sql Queries. Is it an experience or a concept ?

  - by Shantanu Gupta

  I have been working on sql server and front end coding and have usually faced problem formulating queries. I do understand most of the concepts of sql that are needed in formulating queries but whenever some new functionality comes into the picture that can be dont using sql query, i do usually fails resolving them. I am very comfortable with select queries using joins and all such things but when it comes to DML operation i usually fails For every query that i never done before I usually finds uncomfortable with that while creating them. Whenever I goes for an interview I usually faces this problem. Is it their some concept behind approaching on formulating sql queries. Eg. I need to create an sql query such that A table contain single column having duplicate record. I need to remove duplicate records. I know i can find the solution to this query very easily on Googling, but I want to know how everyone comes to the desired result. Is it something like Practice Makes Man Perfect i.e. once you did it, next time you will be able to formulate or their is some logic or concept behind. I could have get my answer of solving above problem simply by posting it on stackoverflow and i would have been with an answer within 5 to 10 minutes but I want to know the reason. How do you work on any new kind of query. Is it a major contribution of experience or some an implementation of concepts. Whenever I learns some new thing in coding section I tries to utilize it wherever I can use it. But here scenario seems to be changed because might be i am lagging in some concepts.

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• F#: Tell me what I'm missing about using Async.Parallel

  - by JBristow

  ok, so I'm doing ProjectEuler Problem #14, and I'm fiddling around with optimizations in order to feel f# out. in the following code: let evenrule n = n / 2L let oddrule n = 3L * n + 1L let applyRule n = if n % 2L = 0L then evenrule n else oddrule n let runRules n = let rec loop a final = if a = 1L then final else loop (applyRule a) (final + 1L) n, loop (int64 n) 1L let testlist = seq {for i in 3 .. 2 .. 1000000 do yield i } let getAns sq = sq |> Seq.head let seqfil (a,acc) (b,curr) = if acc = curr then (a,acc) else if acc < curr then (b,curr) else (a,acc) let pmap f l = seq { for a in l do yield async {return f a} } |> Seq.map Async.RunSynchronously let pmap2 f l = seq { for a in l do yield async {return f a} } |> Async.Parallel |> Async.RunSynchronously let procseq f l = l |> f runRules |> Seq.reduce seqfil |> fst let timer = System.Diagnostics.Stopwatch() timer.Start() let ans1 = testlist |> procseq Seq.map // 837799 00:00:08.6251990 printfn "%A\t%A" ans1 timer.Elapsed timer.Reset() timer.Start() let ans2 = testlist |> procseq pmap printfn "%A\t%A" ans2 timer.Elapsed // 837799 00:00:12.3010250 timer.Reset() timer.Start() let ans3 = testlist |> procseq pmap2 printfn "%A\t%A" ans3 timer.Elapsed // 837799 00:00:58.2413990 timer.Reset() Why does the Async.Parallel code run REALLY slow in comparison to the straight up map? I know I shouldn't see that much of an effect, since I'm only on a dual core mac. Please note that I do NOT want help solving problem #14, I just want to know what's up with my parallel code.

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• Modify Executing Jar file

  - by pinkynobrain

  Hello Stack Overflow friends. I have a simple problem which i fear doesnt have a simple solution and i need advice as to how to proceed. I am developing a java application packaged as and executable JAR but it requires to modify some of its JAR file contents during execution. At this stage i hit a problem because some OS lock the file preventing writes to it. It is essential that the user sees an updated version of the jar file by the time the application exits allthough i can be pretty flexible as to how to achieve this. A clean and efficient solution is obviously prefereable but portability is the only hard requirement. The following are three approaches i can see to solving the problem, feel free to comment on them or suggest others. Tell Java to unlock the JAR file for writing(this doesnt seem possible but it would be the easyest solution) Copy the executable class files to a tempory file on application startup, use a class loader to load these files and unload the ones from the initial JAR file.(Not had much experience with the classloaders but hopefully the JVM would then be smart enough to realize that the original JAR is nolonger in use and so unlock it) Put a Second executable JAR File inside the First, on startup extract the inner jar to e temporaryfile, invoke a new java process and pass it the location of the Outer JAR, first process exits, second process modifys the Outer jar unincumbered.(This will work but im not sure there is a platform independant way of one java app invoking another) I know this is a weird question but any help would be appreciated.

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• How to update QStandartItemModel without freezing the main UI

  - by user1044002

  I'm starting to learn PyQt4 and have been stuck on something for a long time now and can't figure it out myself: Here is the concept: There is a TreeView with custom QStandartItemModel, which gets rebuild every couple of seconds, and can have a lot (hundreds at least) of entries, there also will be additional delegates for the different columns etc. It's fairly complex and the building time for even plain model, without delegates, goes up to .3 sec, which makes the TreeView to freeze. Please advice me for the best approach on solving this. I was thing of somehow building the model in different thread, and eventually sending it to the TreeView, where it would just perform setModel() with the new one, but couldn't make that work. here is some code that may illustrate the problem a bit: from PyQt4.QtCore import * from PyQt4.QtGui import * import sys, os, re, time app = QApplication(sys.argv) REFRESH = 1 class Reloader_Thread(QThread): def __init__(self, parent = None): QThread.__init__(self, parent) self.loaders = ['\\', '--', '|', '/', '--'] self.emit(SIGNAL('refresh')) def run(self): format = '|%d/%b/%Y %H:%M:%S| ' while True: self.emit(SIGNAL('refresh')) self.sleep(REFRESH) class Model(QStandardItemModel): def __init__(self, viewer=None): QStandardItemModel.__init__(self,None) self.build() def build(self): stTime = time.clock() newRows = [] for r in range(1000): row = [] for c in range(12): item = QStandardItem('%s %02d%02d' % (time.strftime('%H"%M\'%S'), r,c)) row.append(item) newRows.append(row) eTime = time.clock() - stTime outStr = 'Build %03f' % eTime format = '|%d/%b/%Y %H:%M:%S| ' stTime = time.clock() self.beginRemoveRows(QModelIndex(), 0, self.rowCount()) self.removeRows(0, self.rowCount()) self.endRemoveRows() eTime = time.clock() - stTime outStr += ', Remove %03f' % eTime stTime = time.clock() numNew = len(newRows) for r in range(numNew): self.appendRow(newRows[r]) eTime = time.clock() - stTime outStr += ', Set %03f' % eTime self.emit(SIGNAL('status'), outStr) self.reset() w = QWidget() w.setGeometry(200,200,800,600) hb = QVBoxLayout(w) tv = QTreeView() tvm = Model(tv) tv.setModel(tvm) sb = QStatusBar() reloader = Reloader_Thread() tvm.connect(tvm, SIGNAL('status'), sb.showMessage) reloader.connect(reloader, SIGNAL('refresh'), tvm.build) reloader.start() hb.addWidget(tv) hb.addWidget(sb) w.show() app.setStyle('plastique') app.processEvents(QEventLoop.AllEvents) app.aboutToQuit.connect(reloader.quit) app.exec_()

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• Open space sitting optimization algorithm

  - by Georgy Bolyuba

  As a result of changes in the company, we have to rearrange our sitting plan: one room with 10 desks in it. Some desks are more popular than others for number of reasons. One solution would be to draw a desk number from a hat. We think there is a better way to do it. We have 10 desks and 10 people. Lets give every person in this contest 50 hypothetical tokens to bid on the desks. There is no limit of how much you bid on one desk, you can put all 50, which would be saying "I want to sit only here, period". You can also say "I do not care" by giving every desk 5 tokens. Important note: nobody knows what other people are doing. Everyone has to decide based only on his/her best interest (sounds familiar?) Now lets say we obtained these hypothetical results: # | Desk# >| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 1 | Alise | 30 | 2 | 2 | 1 | 0 | 0 | 0 | 15 | 0 | 0 | = 50 2 | Bob | 20 | 15 | 0 | 10 | 1 | 1 | 1 | 1 | 1 | 0 | = 50 ... 10 | Zed | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | = 50 Now, what we need to find is that one (or more) configuration(s) that gives us maximum satisfaction (i.e. people get desks they wanted taking into account all the bids and maximizing on the total of the group. Naturally the assumption is the more one bade on the desk the more he/she wants it). Since there are only 10 people, I think we can brute force it looking into all possible configurations, but I was wondering it there is a better algorithm for solving this kind of problems?

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• How do I process a nested list?

  - by ddbeck

  Suppose I have a bulleted list like this: * list item 1 * list item 2 (a parent) ** list item 3 (a child of list item 2) ** list item 4 (a child of list item 2 as well) *** list item 5 (a child of list item 4 and a grand-child of list item 2) * list item 6 I'd like to parse that into a nested list or some other data structure which makes the parent-child relationship between elements explicit (rather than depending on their contents and relative position). For example, here's a list of tuples containing an item and a list of its children (and so forth): [('list item 1',), ('list item 2', [('list item 3',), [('list item 4', [('list item 5'),]] ('list item 6',)] I've attempted to do this with plain Python and some experimentation with Pyparsing, but I'm not making progress. I'm left with two major questions: What's the strategy I need to employ to make this work? I know recursion is part of the solution, but I'm having a hard time making the connection between this and, say, a Fibonacci sequence. I'm certain I'm not the first person to have done this, but I don't know the terminology of the problem to make fruitful searches for more information on this topic. What problems are related to this so that I can learn more about solving these kinds of problems in general?

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• Parsing RSS2 In PHP

  - by mrduclaw

  I'm trying to get content from an RSS2 feed from one of my sites and use it in another site. The feed is here. And the code I'm using is taken from this nice site and has been modified like the following: $doc = new DOMDocument(); $doc->load('http://tripleax.com/john/?feed=rss2'); $arrFeeds = array(); foreach ($doc->getElementsByTagName('item') as $node) { print('<div style="width:100%" class="option"><strong>'); $a = $node->getElementsByTagName('title')->item(0)->nodeValue; print("$a"); print('</strong><br /><span class="option">'); $a = $node->getElementsByTagName('description')->item(0)->nodeValue; print("$a");` } The problem I'm having is, I want to display the entire post's contents. And the description is a sort of the teaser. Changing $node->getElementsByTagName('description')->item(0)->nodeValue to $node->getElementsByTagName('content')->item(0)->nodeValue gives me nothing, and content:encoded is no better. Can someone please point me in the right direction to solving this? Thanks!

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• How to find Part Time development/IT work?

  - by Jonathan

  I've been working in the IT field now for 10 years. Originally trained as an Engineer, started out with C++ and have been a .Net specialist since beta. Currently seconded to a major city and working in the finance industry as freelance, I really feel like i've hit the glass ceiling. Have been contracting now for 5 years as the company politics and frustration of not being promoted and poor pay rises for excellent work but during the last decade of corporate cost cutting took its toll on my morale. Freelance made all the difference and i've had a very decorated career for good clients. What any Engineering student could ever dream of when starting out. The problem is, it doesn't particularly make me happy. It's good work, and i enjoy the problem solving aspects of it and having something to do each day. However there is always a large overhead of non-technical work and dealing with poor managers etc. I guess the Engineering was always a bit of a mistake i made the best out of, and now having 10 years behind a computer hasn't done wonders for my health or eye sight. In a nutshell i am in the process of retraining as a therapist and would like to open my own clinic. However, never having done this before, the fast pace IT skills outdate and the fact that all my experience and skills are non transferrable, i am a little worried. Any ideas how i can find part time IT work as i build up my business? (it's incredibly hard to find freelancing work that doesn't require long hours and overtime). Or other ideas to make the transition easier, and perhaps backout if it financially doesn't work/or i have enough marketing skills? I'd be interested to hear from people who have made a similar transition, successfully or unsuccessfully. Many thanks

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