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• Is it wise to store a big lump of json on a database row

  - by Ieyasu Sawada

  I have this project which stores product details from amazon into the database. Just to give you an idea on how big it is: [{"title":"Genetic Engineering (Opposing Viewpoints)","short_title":"Genetic Engineering ...","brand":"","condition":"","sales_rank":"7171426","binding":"Book","item_detail_url":"http://localhost/wordpress/product/?asin=0737705124","node_list":"Books > Science & Math > Biological Sciences > Biotechnology","node_category":"Books","subcat":"","model_number":"","item_url":"http://localhost/wordpress/wp-content/ecom-plugin-redirects/ecom_redirector.php?id=128","details_url":"http://localhost/wordpress/product/?asin=0737705124","large_image":"http://localhost/wordpress/wp-content/plugins/ecom/img/large-notfound.png","medium_image":"http://localhost/wordpress/wp-content/plugins/ecom/img/medium-notfound.png","small_image":"http://localhost/wordpress/wp-content/plugins/ecom/img/small-notfound.png","thumbnail_image":"http://localhost/wordpress/wp-content/plugins/ecom/img/thumbnail-notfound.png","tiny_img":"http://localhost/wordpress/wp-content/plugins/ecom/img/tiny-notfound.png","swatch_img":"http://localhost/wordpress/wp-content/plugins/ecom/img/swatch-notfound.png","total_images":"6","amount":"33.70","currency":"$","long_currency":"USD","price":"$33.70","price_type":"List Price","show_price_type":"0","stars_url":"","product_review":"","rating":"","yellow_star_class":"","white_star_class":"","rating_text":" of 5","reviews_url":"","review_label":"","reviews_label":"Read all ","review_count":"","create_review_url":"http://localhost/wordpress/wp-content/ecom-plugin-redirects/ecom_redirector.php?id=132","create_review_label":"Write a review","buy_url":"http://localhost/wordpress/wp-content/ecom-plugin-redirects/ecom_redirector.php?id=19186","add_to_cart_action":"http://localhost/wordpress/wp-content/ecom-plugin-redirects/add_to_cart.php","asin":"0737705124","status":"Only 7 left in stock.","snippet_condition":"in_stock","status_class":"ninstck","customer_images":["http://localhost/wordpress/wp-content/uploads/2013/10/ecom_images/51M2vvFvs2BL.jpg","http://localhost/wordpress/wp-content/uploads/2013/10/ecom_images/31FIM-YIUrL.jpg","http://localhost/wordpress/wp-content/uploads/2013/10/ecom_images/51M2vvFvs2BL.jpg","http://localhost/wordpress/wp-content/uploads/2013/10/ecom_images/51M2vvFvs2BL.jpg"],"disclaimer":"","item_attributes":[{"attr":"Author","value":"Greenhaven Press"},{"attr":"Binding","value":"Hardcover"},{"attr":"EAN","value":"9780737705126"},{"attr":"Edition","value":"1"},{"attr":"ISBN","value":"0737705124"},{"attr":"Label","value":"Greenhaven Press"},{"attr":"Manufacturer","value":"Greenhaven Press"},{"attr":"NumberOfItems","value":"1"},{"attr":"NumberOfPages","value":"224"},{"attr":"ProductGroup","value":"Book"},{"attr":"ProductTypeName","value":"ABIS_BOOK"},{"attr":"PublicationDate","value":"2000-06"},{"attr":"Publisher","value":"Greenhaven Press"},{"attr":"SKU","value":"G0737705124I2N00"},{"attr":"Studio","value":"Greenhaven Press"},{"attr":"Title","value":"Genetic Engineering (Opposing Viewpoints)"}],"customer_review_url":"http://localhost/wordpress/wp-content/ecom-customer-reviews/0737705124.html","flickr_results":["http://localhost/wordpress/wp-content/uploads/2013/10/ecom_images/5105560852_06c7d06f14_m.jpg"],"freebase_text":"No around the web data available yet","freebase_image":"http://localhost/wordpress/wp-content/plugins/ecom/img/freebase-notfound.jpg","ebay_related_items":[{"title":"Genetic Engineering (Introducing Issues With Opposing Viewpoints), , Good Book","image":"http://localhost/wordpress/wp-content/uploads/2013/10/ecom_images/140.jpg","url":"http://localhost/wordpress/wp-content/ecom-plugin-redirects/ecom_redirector.php?id=12165","currency_id":"$","current_price":"26.2"},{"title":"Genetic Engineering Opposing Viewpoints by DAVID BENDER - 1964 Hardcover","image":"http://localhost/wordpress/wp-content/uploads/2013/10/ecom_images/140.jpg","url":"http://localhost/wordpress/wp-content/ecom-plugin-redirects/ecom_redirector.php?id=130","currency_id":"AUD","current_price":"11.99"}],"no_follow":"rel=\"nofollow\"","new_tab":"target=\"_blank\"","related_products":[],"super_saver_shipping":"","shipping_availability":"","total_offers":"7","added_to_cart":""}] So the structure for the table is: asin title details (the product details in json) Will the performance suffer if I have to store like 10,000 products? Is there any other way of doing this? I'm thinking of the following, but the current setup is really the most convenient one since I also have to use the data on the client side: store the product details in a file. So something like ASIN123.json store the product details in one big file. (I'm guessing it will be a drag to extract data from this file) store each of the fields in the details in its own table field Thanks in advance!

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• Are CK Metrics still considered useful? Is there an open source tool to help?

  - by DeveloperDon

  Chidamber & Kemerer proposed several metrics for object oriented code. Among them, depth of inheritance tree, weighted number of methods, number of member functions, number of children, and coupling between objects. Using a base of code, they tried to correlated these metrics to the defect density and maintenance effort using covariant analysis. Are these metrics actionable in projects? Perhaps they can guide refactoring. For example weighted number of methods might show which God classes needed to be broken into more cohesive classes that address a single concern. Is there approach superseded by a better method, and is there a tool that can identify problem code, particularly in moderately large project being handed off to a new developer or team?

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• How do I classify using GLCM and SVM Classifier in Matlab?

  - by Gomathi

  I'm on a project of liver tumor segmentation and classification. I used Region Growing and FCM for liver and tumor segmentation respectively. Then, I used Gray Level Co-occurence matrix for texture feature extraction. I have to use Support Vector Machine for Classification. But I don't know how to normalize the feature vectors. Can anyone tell how to program it in Matlab? To the GLCM program, I gave the tumor segmented image as input. Was I correct? If so, I think, then, my output will also be correct. My glcm coding, as far as I have tried is, I = imread('fzliver3.jpg'); GLCM = graycomatrix(I,'Offset',[2 0;0 2]); stats = graycoprops(GLCM,'all') t1= struct2array(stats) I2 = imread('fzliver4.jpg'); GLCM2 = graycomatrix(I2,'Offset',[2 0;0 2]); stats2 = graycoprops(GLCM2,'all') t2= struct2array(stats2) I3 = imread('fzliver5.jpg'); GLCM3 = graycomatrix(I3,'Offset',[2 0;0 2]); stats3 = graycoprops(GLCM3,'all') t3= struct2array(stats3) t=[t1;t2;t3] xmin = min(t); xmax = max(t); scale = xmax-xmin; tf=(x-xmin)/scale Was this a correct implementation? Also, I get an error at the last line. My output is: stats = Contrast: [0.0510 0.0503] Correlation: [0.9513 0.9519] Energy: [0.8988 0.8988] Homogeneity: [0.9930 0.9935] t1 = Columns 1 through 6 0.0510 0.0503 0.9513 0.9519 0.8988 0.8988 Columns 7 through 8 0.9930 0.9935 stats2 = Contrast: [0.0345 0.0339] Correlation: [0.8223 0.8255] Energy: [0.9616 0.9617] Homogeneity: [0.9957 0.9957] t2 = Columns 1 through 6 0.0345 0.0339 0.8223 0.8255 0.9616 0.9617 Columns 7 through 8 0.9957 0.9957 stats3 = Contrast: [0.0230 0.0246] Correlation: [0.7450 0.7270] Energy: [0.9815 0.9813] Homogeneity: [0.9971 0.9970] t3 = Columns 1 through 6 0.0230 0.0246 0.7450 0.7270 0.9815 0.9813 Columns 7 through 8 0.9971 0.9970 t = Columns 1 through 6 0.0510 0.0503 0.9513 0.9519 0.8988 0.8988 0.0345 0.0339 0.8223 0.8255 0.9616 0.9617 0.0230 0.0246 0.7450 0.7270 0.9815 0.9813 Columns 7 through 8 0.9930 0.9935 0.9957 0.9957 0.9971 0.9970 ??? Error using ==> minus Matrix dimensions must agree. The images are:

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• Should I migrate to MVC3?

  - by eestein

  Hi everyone. I have a MVC2 project, my question is: should I migrate to MVC3? Why? I'd like the opinion of some who already migrated, or at least used MVC3 and MVC2. Already read http://weblogs.asp.net/scottgu/archive/2011/01/13/announcing-release-of-asp-net-mvc-3-iis-express-sql-ce-4-web-farm-framework-orchard-webmatrix.aspx and I already know about the described tool for migrating: http://blogs.msdn.com/b/marcinon/archive/2011/01/13/mvc-3-project-upgrade-tool.aspx What I'd really appreciate is your valuable insight. Best regards.

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• Caching large amount of ajax returned objects

  - by ofcapl

  I'm building an application which fetches large amount of items with ajax requests via other application API. It returns me 6k - 30k js objects which are used multiple times across various application views (sorting, filtering etc.). I would like to avoid querying API every time for such big list so I decided to cache this data somehow. I was thinking about various solutions: saving it to localstorage, using some caching library (e.g. locachejs), storing in js var. I'm not an expert so I would like to hear Your suggestions about each (or one of these) solution, about its pros and cons. Every help will be very appreciated.

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• Is there an established convention for separating Windows file names in a string?

  - by Heinzi

  I have a function which needs to output a string containing a list of file paths. I can choose the separation character but I cannot change the data type (e.g. I cannot return a List<string> or something like that). Wanting to use some well-established convention, my first intuition was to use the semicolon, similar to what Windows's PATH and Java's CLASSPATH (on Windows) environment variables do: C:\somedir\somefile.txt;C:\someotherdir\someotherfile.txt However, I was surprised to notice that ; is a valid character in an NTFS file name. So, is the established best practice to just ignore this fact (i.e. "no sane person should use ; in a file name and if they do, it's their own fault") or is there some other established character for separating Windows paths or files? (The pipe (|) might be a good choice, but I have not seen it used anywhere yet for this purpose.)

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• Explain Model View Controller

  - by Channel72

  My experience with developing dynamic websites is limited mostly to Java servlets. I've used Tomcat to develop various Java servlets, and I wouldn't hesitate to say that I'm reasonably proficient with this technology, as well as with client-side HTML/CSS/Javascript for the front-end. When I think "dynamic website", I think: user requests a URL with a query string, server receives the query, and then proceeds to output HTML dynamically in order to respond to the query. This often involves communication with a database in order to fetch requested data for display. This is basically the idea behind the doGet method of a Java HttpServlet. But these days, I'm hearing more and more about newer frameworks such as Django and Ruby on Rails, all of which take advantage of the "Model View Controller" architecture. I've read various articles which explain MVC, but I'm having trouble really understanding the benefits. I understand that the general idea is to separate business logic from UI logic, but I fail to see how this is anything really different from normal web programming. Web programming, by it's very nature, forces you to separate business logic (back-end server-side programming) from UI programming (client-side HTML or Javascript), because the two exist in entirely different spheres of programming. Question: What does MVC offer over something like a Java servlet, and more importantly, what exactly is MVC and how is it different from what you would normally do to develop a dynamic website using a more traditional approach such as a Java servlet (or even something older like CGI). If possible, when explaining MVC, please provide an example which illustrates how MVC is applied to the web development process, and how it is beneficial.

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• Where can I find video resources of people programming?

  - by Corey

  This might be a strange question. I'm looking for videos of people actively coding something while explaining it. However, I don't want is a beginner video that delves into what variables and objects are. Nick Gravelyn's tile engine tutorial is a great example of what I'm looking for. (He actually used to host the full, unbroken video files in his site's archive, but I guess he took them down...) I tend to learn best by "action" examples; it's difficult for me to learn by reading through documentation and text tutorials, but if I see somebody actively doing a task, I can immediately register it and apply it myself. I'm hard-of-hearing, so I would really prefer that if the video has a lot of talking, it have captioning or subtitling of some sort, or at the very least, a transcript. The tile engine videos did not have captions, but the code he was writing was very self-documenting, so I understood it for the most part. I've gone through most of the relevant GoogleDevelopers and GoogleTechTalks videos on Youtube, so those need not apply. Are there any resources out there, or even websites dedicated to this kind of thing?

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• Troubleshooting VC++ DLL in VB.Net

  - by Jolyon

  I'm trying to make a solution in Visual Studio that consists of a VC++ DLL and a VB.Net application. To figure this out, I created a VC++ Class Library project, with the following code (I removed all the junk the wizard creates): mathfuncs.cpp: #include "MathFuncs.h" namespace MathFuncs { double MyMathFuncs::Add(double a, double b) { return a + b; } } mathfuncs.h: using namespace System; namespace MathFuncs { public ref class MyMathFuncs { public: static double Add(double a, double b); }; } This compiles quite happily. I can then add a VC++ console project to the solution, add a reference to the original project for this new project, and call it as follows: test.cpp: using namespace System; int main(array<System::String ^> ^args) { double a = 7.4; int b = 99; Console::WriteLine("a + b = {0}", MathFuncs::MyMathFuncs::Add(a, b)); return 0; } This works just fine, and will build to test.exe and mathsfuncs.dll. However, I want to use a VB.Net project to call the DLL. To do this, I add a VB.Net project to the solution, make it the startup project, and add a reference to the original project. Then, I attempt to use it as follows: MsgBox(MathFuncs.MyMathFuncs.Add(1, 2)) However, when I run this code, it gives me an error: "Could not load file or assembly 'MathFuncsAssembly, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null' or one of its dependencies. An attempt was made to load a program with an incorrect format." Do I need to expose the method somehow? I'm using Visual Studio 2008 Professional.

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• How can I merge two SubVersion branches to one working copy without committing?

  - by Eric Belair

  My current SubVersion workflow is like so: The trunk is used to make small content changes and bug fixes to the main source code. Branches are used for adding/editing enhancements and projects. So, trunk changes are made, tested, committed and deployed pretty quickly. Whereas, enhancements and projects need additional user testing and approval. At time, I have two branches that need testing and approval at the same time. I don't want to merge to the trunk and commit until the changes are fully tested and approved. What I need to do is merge both branches to one working copy without any commits. I am using Tortoise SVN, and when I try to merge the second branch, I get an error message: Cannot merge into a working copy that has local modifications Is there a way that I can do this without committing either merge?

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• What should you leave behind for your successors?

  - by SnOrfus

  Assume that you're a sole developer leaving a job. What kind of information/material, outside of the code itself, should you create and leave behind for your replacement? An obvious answer is "whatever you would want at a new job" for sure, but it's been a while since I started a new job, and I forget what the most important things that I needed were back then. I'm thinking: accounts/passwords location of equpiment What else?

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• Writing a job requirement for a web application developer

  - by Raul Agrait

  I'm currently writing a job requirement for a software engineer position for my company, in which we are looking for a developer to work on client-side web application work. How should I title the job title / position? I don't necessarily want to call it a "Web Developer", for fear that it might attract more designer-y types. On the other hand, "Software Engineer" doesn't really give the indication that the work, while application based, will be web-based. Is "Web Application Software Engineer" a valid position title? Also, I'm somewhat torn on what the required skills set should be. I don't necessarily think that the ideal candidate should have x years of experience in say, JavaScript or ActionScript, but rather am just looking for someone who has experience in developing client-side applications, and is willing to learn and develop web applications. My current attempt at this, is that I have a section in which I state: Experience in the following frameworks and technologies are a plus, but not necessarily required for the position:

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• Java HttpURLConnection class Program

  - by pandu

  I am learning java. Here is the sample code of HttpURLConnection class usage in some text book import java.net.*; import java.io.*; import java.util.*; class HttpURLDemo { public static void main(String args[]) throws Exception { URL hp = new URL("http://www.google.com"); HttpURLConnection hpCon = (HttpURLConnection) hp.openConnection(); // Display request method. System.out.println("Request method is " + hpCon.getRequestMethod()); // Display response code. System.out.println("Response code is " + hpCon.getResponseCode()); // Display response message. System.out.println("Response Message is " + hpCon.getResponseMessage()); // Get a list of the header fields and a set // of the header keys. Map<String, List<String>> hdrMap = hpCon.getHeaderFields(); Set<String> hdrField = hdrMap.keySet(); System.out.println("\nHere is the header:"); // Display all header keys and values. for(String k : hdrField) { System.out.println("Key: " + k + " Value: " + hdrMap.get(k)); } } } Question is Why hpCon Object is declared in the following way? HttpURLConnection hpCon = (HttpURLConnection) hp.openConnection(); instead of declaring like this HttpURLConnection hpCon = new HttpURLConnection(); Author provided the following explanation. I cant understand Java provides a subclass of URLConnection that provides support for HTTP connections. This class is called HttpURLConnection. You obtain an HttpURLConnection in the same way just shown, by calling openConnection( ) on a URL object, but you must cast the result to HttpURLConnection. (Of course, you must make sure that you are actually opening an HTTP connection.) Once you have obtained a reference to an HttpURLConnection object, you can use any of the methods inherited from URLConnection

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• Web Application Tasks Estimation

  - by Ali

  I know the answer depends on the exact project and its requirements but i am asking on the avarage % of the total time goes into the tasks of the web application development statistically from your own experiance. While developing a web application (database driven) How much % of time does each of the following activities usually takes: -- database creation & all related stored procedures -- server side development -- client side development -- layout settings and designing I know there are lots of great web application developers around here and each one of you have done fair amount of web development and as a result there could be an almost fixed percentage of time going to each of the above activities of web developments for standard projects Update : I am not expecting someone to tell me number of hours i am asking about the average percentage of time that goes on each of the activities as per your experience i.e. server side dev 50%, client side development 20% ,,,,, I repeat there will be lots of cases that differs from the standard depending on the exact requirments of each web application project but here i am asking about Avarage for standard (no special requirment) web project

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• What are algorithmic paradigms?

  - by Vaibhav Agarwal

  We generally talk about paradigms of programming as functional, procedural, object oriented, imperative etc but what should I reply when I am asked the paradigms of algorithms? For example are Travelling Salesman Problem, Dijkstra Shortest Path Algorithm, Euclid GCD Algorithm, Binary search, Kruskal's Minimum Spanning Tree, Tower of Hanoi paradigms of algorithms? Should I answer the data structures I would use to design these algorithms?

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• How to name an subclass that add a minor, detailed thing?

  - by Louis Rhys

  What is the most concise (yet descriptive) way of naming a subclass that only add a specific minor thing to the parent? I encountered this case a lot in WPF, where sometime I have to add a small functionality to an out-of-the-box control for specific cases. Example: TreeView doesn't change the SelectedItem on right-click, but I have to make one that does in my application. Some possible names are TreeViewThatChangesSelectedItemOnRightClick (way too wordy and maybe difficult to read because there is so many words concantenated together) TreeView_SelectedItemChangesOnRightClick (slightly more readable, but still too wordy and the underscore also breaks the normal convention for class names) TreeViewThatChangesSIOnRC (non-obvious acronym), ExtendedTreeView (more concise, but doesn't describe what it is doing. Besides, I already found a class called this in the library, that I don't want to use/modify in my application). LouisTreeView, MyTreeView, etc. (doesn't describe what it is doing). It seems that I can't find a name which sounds right. What do you do in situation like this?

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• Visual Web Developer 2010 Express, automated testing, and SVN

  - by Mr. Jefferson

  We have an HTML designer who is not a developer but needs to modify .aspx files from our ASP.NET 2.0 projects from time to time in order to get CSS to work properly with them. Currently, this involves giving her the .aspx page by itself, which she opens and edits via Visual Studio 2008 (her computer used to be a developer's). I'm considering getting her set up with Visual Web Developer 2010 Express and Subversion access so she can be more independent, but I wanted to make sure VS Express will work properly with what we do. So: Does VWD 2010 Express support automated tests? If no to the above, what happens when it opens a solution file that includes a test project, modifies it, and saves it? Are there any potential snags with setting up AnkhSVN with VWD 2010 Express?

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• Structuring multi-threaded programs

  - by davidk01

  Are there any canonical sources for learning how to structure multi-threaded programs? Even with all the concurrency utility classes that Java provides I'm having a hard time properly structuring multi-threaded programs. Whenever threads are involved my code becomes very brittle, any little change can potentially break the program because the code that jumps back and forth between the threads tends to be very convoluted.

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• A deque based on binary trees

  - by Greg Ros

  This is a simple immutable deque based on binary trees. What do you think about it? Does this kind of data structure, or possibly an improvement thereof, seem useful? How could I improve it, preferably without getting rid of its strengths? (Not in the sense of more operations, in the sense of different design) Does this sort of thing have a name? Red nodes are newly instantiated; blue ones are reused. Nodes aren't actually red or anything, it's just for emphasis.

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• Integration of routes that are not resources in an MVC REST style application

  - by Emil Lerch

  I would like to keep my application relatively REST-pure for the sake of consistency, but I'm struggling philosophically with the relatively few views (maybe just one) that I'll need to build that don't relate to resources directly, and therefore do not fit into a REST style. As an example, take the home page. Ruby on rails seems to bail on their otherwise RESTful approach for this very basic need of all web sites. The home page appears special: You can get it, but a get at the resource level is supposed to give you a collection of elements. I can imagine this being the list of routes maybe, but that seems a stretch, and doesn't address anything else. Getting the home page by id doesn't seem to make a whole lot of sense - what's the element of a home collection? Again, maybe routes, but a get on a route would do what? Redirect? This feels odd. You can't delete it (arguably you could allow this for administrators) Adding a second one doesn't make sense except possibly if the elements were routes Updating it might make sense for administrators, but AFAIK REST doesn't describe updates on the resource directly, only elements of the resource (this article explicitly says "UNUSED" for PUTS on the resource) Is the "right" thing to do just to special case these types of things? At the end of the day, I can wrap my head around most of applications being gathered around resources...I can't think of another good example other than a home page, but since that's the start of an application, I think it warrants some thought.

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• Question about casting a class in Java with generics

  - by Florian F

  In Java 6 Class<? extends ArrayList<?>> a = ArrayList.class; gives and error, but Class<? extends ArrayList<?>> b = (Class<? extends ArrayList<?>>)ArrayList.class; gives a warning. Why is (a) an error? What is it, that Java needs to do in the assignment, if not the cast shown in (b)? And why isn't ArrayList compatible with ArrayList? I know one is "raw" and the other is "generic", but what is it you can do with an ArrayList and not with an ArrayList, or the other way around?

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• How can Swift be so much faster than Objective-C?

  - by Yellow

  Apple launched its new programming language Swift today. In the presentation, they made some performance comparisons between Objective-C and Python. The following is a picture of one of their slides, of a comparison of those three languages performing some complex object sort: There was an even more incredible graph about a performance comparison working on some encryption algorithm. Obviously this is a marketing talk, and they didn't go into detail on how this was implemented in each. I leaves me wondering though: how can a new programming language be so much faster? In this example, surely you just have a bad Objective-C compiler or you're doing something in a less efficient way? How else would you explain a 40% performance increase? I understand that garbage collection/automated reference control might produce some additional overhead, but this much?

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• Is there a distributed project management software like Redmine?

  - by Tobias Kienzler

  I am quite familiar with and love using git, among other reasons due to its distributed nature. Now I'd like to set up some similarly distributed (FOSS) Project Management software with features similar to what Redmine offers, such as Issue & time tracking, milestones Gantt charts, calendar git integration, maybe some automatic linking of commits and issues Wiki (preferably with Mathjax support) Forum, news, notifications Multiple Projects However, I am looking for a solution that does not require a permanently accesible server, i.e. like in git, each user should have their own copy which can be easily synchronized with others. However it should be possible to not have a copy of every Project on every machine. Since trac uses multiple instances for multiple projects anyway, I was considering using that, but I neither know how well it adapts to simply giting the database itself (which would be be easiest way to handle the distribution due to git being used anyway), nor does it include all of Redmine's feature. So, can you recommend me a distributed project management software? If your suggestion is a software that usually runs on a server please include a description of the distribution method (e.g. whether simply putting the data in a git repository would do the trick), and if it's e.g. trac, please mention plugins required to include the features mentioned.

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• Merge sort versus quick sort performance

  - by Giorgio

  I have implemented merge sort and quick sort using C (GCC 4.4.3 on Ubuntu 10.04 running on a 4 GB RAM laptop with an Intel DUO CPU at 2GHz) and I wanted to compare the performance of the two algorithms. The prototypes of the sorting functions are: void merge_sort(const char **lines, int start, int end); void quick_sort(const char **lines, int start, int end); i.e. both take an array of pointers to strings and sort the elements with index i : start <= i <= end. I have produced some files containing random strings with length on average 4.5 characters. The test files range from 100 lines to 10000000 lines. I was a bit surprised by the results because, even though I know that merge sort has complexity O(n log(n)) while quick sort is O(n^2), I have often read that on average quick sort should be as fast as merge sort. However, my results are the following. Up to 10000 strings, both algorithms perform equally well. For 10000 strings, both require about 0.007 seconds. For 100000 strings, merge sort is slightly faster with 0.095 s against 0.121 s. For 1000000 strings merge sort takes 1.287 s against 5.233 s of quick sort. For 5000000 strings merge sort takes 7.582 s against 118.240 s of quick sort. For 10000000 strings merge sort takes 16.305 s against 1202.918 s of quick sort. So my question is: are my results as expected, meaning that quick sort is comparable in speed to merge sort for small inputs but, as the size of the input data grows, the fact that its complexity is quadratic will become evident? Here is a sketch of what I did. In the merge sort implementation, the partitioning consists in calling merge sort recursively, i.e. merge_sort(lines, start, (start + end) / 2); merge_sort(lines, 1 + (start + end) / 2, end); Merging of the two sorted sub-array is performed by reading the data from the array lines and writing it to a global temporary array of pointers (this global array is allocate only once). After each merge the pointers are copied back to the original array. So the strings are stored once but I need twice as much memory for the pointers. For quick sort, the partition function chooses the last element of the array to sort as the pivot and scans the previous elements in one loop. After it has produced a partition of the type start ... {elements <= pivot} ... pivotIndex ... {elements > pivot} ... end it calls itself recursively: quick_sort(lines, start, pivotIndex - 1); quick_sort(lines, pivotIndex + 1, end); Note that this quick sort implementation sorts the array in-place and does not require additional memory, therefore it is more memory efficient than the merge sort implementation. So my question is: is there a better way to implement quick sort that is worthwhile trying out? If I improve the quick sort implementation and perform more tests on different data sets (computing the average of the running times on different data sets) can I expect a better performance of quick sort wrt merge sort? EDIT Thank you for your answers. My implementation is in-place and is based on the pseudo-code I have found on wikipedia in Section In-place version: function partition(array, 'left', 'right', 'pivotIndex') where I choose the last element in the range to be sorted as a pivot, i.e. pivotIndex := right. I have checked the code over and over again and it seems correct to me. In order to rule out the case that I am using the wrong implementation I have uploaded the source code on github (in case you would like to take a look at it). Your answers seem to suggest that I am using the wrong test data. I will look into it and try out different test data sets. I will report as soon as I have some results.

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• Database vs Networking

  - by user16258

  I have completed my diploma in (IT) and now pursuing degree, i am in last semester of my B.E(I.T). I want to do specialization either in Database(oracle) or in Networking(cisco). Which one of two will be in more demand in near future, i know it's all about interest but still i would like to know your opinion. Most of people say that a network engineer is never paid as better as a programmer or a DBA, and few says they do get paid well. What would be the scope if i clear my CCNA and CCNP exams, or either OCA & OCP exams, what would be more rewarding. Also i have read somewhere that most of the task of DBA will be automated so in future demand of a DBA will reduce. I would also like to hear from Network engineers what's the scenario out there in India. Thanks

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