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• Using * in SELECT Query

  - by libregeek

  I am currently porting an application written in MySQL3 and PHP4 to MySQL5 and PHP5. On analysis I found several SQL queries which uses "select * from tablename" even if only one column(field) is processed in PHP. The table has almost 60 columns and it has a primary key. In most cases, the only column used is id which is the primary key. Will there be any performance boost if I use queries in which the column names are explicitly mentioned instead of * ? (In this application there is only one method which we need all the columns and all other methods return only a subset of the columns)

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• Make UILabel show "No results" instead of "nan"

  - by Mike Rychev

  I have a small app, where user can make some calculations and solve equations. For example, if in a square equation discriminant is less than zero, the x1 and x2 values are "nan", so when I assign x1 and x2 values to UILabels they show "nan" as well. Writing a lot of if's like if(D<0) [label setText:[NSString stringWithFormat: @"No solutions"]]; Doesn't help-there are too many cases. I want to check if after [label setText:[NSString stringWithFormat: @"%f", x]]; label's value is "nan", the label's value will be set to @"No solutions". Doing simple if(label==@"nan") { //code } doesn't help. Thanks in advance!

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• Minimum cost strongly connected digraph

  - by Kazoom

  I have a digraph which is strongly connected (i.e. there is a path from i to j and j to i for each pair of nodes (i, j) in the graph G). I wish to find a strongly connected graph out of this graph such that the sum of all edges is the least. To put it differently, I need to get rid of edges in such a way that after removing them, the graph will still be strongly connected and of least cost for the sum of edges. I think it's an NP hard problem. I'm looking for an optimal solution, not approximation, for a small set of data like 20 nodes. Edit A more general description: Given a grap G(V,E) find a graph G'(V,E') such that if there exists a path from v1 to v2 in G than there also exists a path between v1 and v2 in G' and sum of each ei in E' is the least possible. so its similar to finding a minimum equivalent graph, only here we want to minimize the sum of edge weights rather than sum of edges. Edit: My approach so far: I thought of solving it using TSP with multiple visits, but it is not correct. My goal here is to cover each city but using a minimum cost path. So, it's more like the cover set problem, I guess, but I'm not exactly sure. I'm required to cover each and every city using paths whose total cost is minimum, so visiting already visited paths multiple times does not add to the cost.

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• Intersection of two querysets in django

  - by unagimiyagi

  Hello, I can't do an AND on two querysets. As in, q1 & q2. I get the empty set and I do not know why. I have tested this with the simplest cases. I am using django 1.1.1 I have basically objects like this: item1 name="Joe" color = "blue" item2 name="Jim" color = "blue" color = "white" item3 name="John" color = "red" color = "white" Is there something weird about having a many-to-many relationship or what am I missing? queryset1 = Item.objects.filter(color="blue") this gives (item1, item2) queryset2 = Item.objects.filter(color="white") this gives (item2, item3) queryset1 & queryset2 gives me the empty set [] The OR operator works fine (I'm using "|" ) Why is this so?

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• Programmatic Bot Detection

  - by matt

  Hi, I need to write some code to analyze whether or not a given user on our site is a bot. If it's a bot, we'll take some specific action. Looking at the User Agent is not something that is successful for anything but friendly bots, as you can specify any user agent you want in a bot. I'm after behaviors of unfriendly bots. Various ideas I've had so far are: If you don't have a browser ID If you don't have a session ID Unable to write a cookie Obviously, there are some cases where a legitimate user will look like a bot, but that's ok. Are there other programmatic ways to detect a bot, or either detect something that looks like a bot? thanks!

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• Memory problems while code is running (Python, Networkx)

  - by MIN SU PARK

  I made a code for generate a graph with 379613734 edges. But the code couldn't be finished because of memory. It takes about 97% of server memory when it go through 62 million lines. So I killed it. Do you have any idea to solve this problem? My code is like this: import os, sys import time import networkx as nx G = nx.Graph() ptime = time.time() j = 1 for line in open("./US_Health_Links.txt", 'r'): #for line in open("./test_network.txt", 'r'): follower = line.strip().split()[0] followee = line.strip().split()[1] G.add_edge(follower, followee) if j%1000000 == 0: print j*1.0/1000000, "million lines done", time.time() - ptime ptime = time.time() j += 1 DG = G.to_directed() # P = nx.path_graph(DG) Nn_G = G.number_of_nodes() N_CC = nx.number_connected_components(G) LCC = nx.connected_component_subgraphs(G)[0] n_LCC = LCC.nodes() Nn_LCC = LCC.number_of_nodes() inDegree = DG.in_degree() outDegree = DG.out_degree() Density = nx.density(G) # Diameter = nx.diameter(G) # Centrality = nx.betweenness_centrality(PDG, normalized=True, weighted_edges=False) # Clustering = nx.average_clustering(G) print "number of nodes in G\t" + str(Nn_G) + '\n' + "number of CC in G\t" + str(N_CC) + '\n' + "number of nodes in LCC\t" + str(Nn_LCC) + '\n' + "Density of G\t" + str(Density) + '\n' # sys.exit() # j += 1 The edge data is like this: 1000 1001 1000245 1020191 1000 10267352 1000653 10957902 1000 11039092 1000 1118691 10346 11882 1000 1228281 1000 1247041 1000 12965332 121340 13027572 1000 13075072 1000 13183162 1000 13250162 1214 13326292 1000 13452672 1000 13844892 1000 14061830 12340 1406481 1000 14134703 1000 14216951 1000 14254402 12134 14258044 1000 14270791 1000 14278978 12134 14313332 1000 14392970 1000 14441172 1000 14497568 1000 14502775 1000 14595635 1000 14620544 1000 14632615 10234 14680596 1000 14956164 10230 14998341 112000 15132211 1000 15145450 100 15285998 1000 15288974 1000 15300187 1000 1532061 1000 15326300 Lastly, is there anybody who has an experience to analyze Twitter link data? It's quite hard to me to take a directed graph and calculate average/median indegree and outdegree of nodes. Any help or idea?

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• Use the [Serializable] attribute or subclassing from MarshalByRefObject?

  - by Theo Lenndorff

  I'd like to use an object across AppDomains. For this I can use the [Serializeable] attribute: [Serializable] class MyClass { public string GetSomeString() { return "someString" } } Or subclass from MarshalByRefObject: class MyClass: MarshalByRefObject { public string GetSomeString() { return "someString" } } In both cases I can use the class like this: AppDomain appDomain = AppDomain.CreateDomain("AppDomain"); MyClass myObject = (MyClass)appDomain.CreateInstanceAndUnwrap( typeof(MyClass).Assembly.FullName, typeof(MyClass).FullName); Console.WriteLine(myObject.GetSomeString()); Why do both approaches seem to have the same effect? What is the difference in both approaches? When should I favor the one approach over the other? EDIT: At the surface I know that there are differences between both mechanisms, but if someone jumped out of a bush and asked me the question I couldn't give him a proper answer. The questions are quite open questions. I hoped that someone can explain it better than I could do.

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• ASP.NET MVC Session usage

  - by Ben

  Currently I am using ViewData or TempData for object persistance in my ASP.NET MVC application. However in a few cases where I am storing objects into ViewData through my base controller class, I am hitting the database on every request (when ViewData["whatever"] == null). It would be good to persist these into something with a longer lifespan, namely session. Similarly in an order processing pipeline, I don't want things like Order to be saved to the database on creation. I would rather populate the object in memory and then when the order gets to a certain state, save it. So it would seem that session is the best place for this? Or would you recommend that in the case of order, to retrieve the order from the database on each request, rather than using session? Thoughts, suggestions appreciated. Thanks Ben

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• Recognize Dates In A String

  - by Tim Scott

  I want a class something like this: public interface IDateRecognizer { DateTime[] Recognize(string s); } The dates might exist anywhere in the string and might be any format. For now, I could limit to U.S. culture formats. The dates would not be delimited in any way. They might have arbitrary amounts of whitespace between parts of the date. The ideas I have are: ANTLR Regex Hand rolled I have never used ANTLR, so I would be learning from scratch. I wonder if there are libraries or code samples out there that do something similar that could jump start me. Is ANTLR too heavy for such a narrow use? I have used Regex a lot before, but I hate it for all the reasons that most people hate it. I could certainly hand roll it but I'd rather not re-solve a solved problem. Suggestions? UPDATE: Here is an example. Given this input: This is a date 11/3/63. Here is another one: November 03, 1963; and another one Nov 03, 63 and some more (11/03/1963). The dates could be in any U.S. format. They might have dashes like 11-2-1963 or weird extra whitespace inside like this: Nov   3,   1963, and even maybe the comma is missing like [Nov 3 63] but that's an edge case. The output should be an array of seven DateTimes. Each date would be the same: 11/03/1963 00:00:00.

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• Is there a non-blocking version of MessageBox.Show (or something like it)?

  - by Dan Tao

  Often you just want to notify the user that something has occurred, but there's really no need for any input from them. In this common scenario, I sometimes see code like this: MessageBox.Show("Something has occurred", "Something", MessageBoxButtons.OK); This code, as we all know, causes a little pop-up window to appear with only an OK button. Now here's the thing: this code blocks (the UI thread). But in the vast majority of cases, it seems to me, if you only have an OK button, there's very little need to block. (Isn't the purpose of blocking typically to receive some input from the user? And if the user's only choice is "OK," in this typical case, isn't blocking pretty pointless?) Obviously I could just write my own little form that does basically exactly what MessageBox.Show does, except that it returns nothing (no DialogResult) and doesn't block. But I was just wondering if something like this exists already that I didn't know about.

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• Use case modelling for calculator

  - by kyrogue

  hi, i need help modelling a use case diagram from a topic, it will be in java GUI Design a Calculator that 1.Allow user to key in a legitimate arithmetic statement that involves number, operator +, - and bracket '(' and ')' ; 2.When user press “Calculate” button, display result; 3.Some legitimate statement would be ((3+2)-4+2) (equals 3) and (-2+3)-(3-1) (equals -1); 4.You should NOT use a pre-existing function that just take in the statement as a parameter and returns the result but you should write the logic of parsing every character in your code. 5.Store the last statement and answer so it is displayed when user press the “Last calculation” button. i have designed two use case diagrams using UML on netbeans 6.5.1, one of the use case i am not sure whether is it containing too much use cases etc, while the other is what i think could be too vague for the topic.i hope to get some feedback on whether the use case diagram are appropriate, thanks.

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• How do I get a Mac ".command" file to automatically quit after running a shell script?

  - by LOlliffe

  In my shell script, my last lines are: ... echo "$l" done done exit I have Terminal preference set to "When the shell exits: Close the window". In all other cases, when I type "exit" or "logout", in Terminal, the window closes, but for this ".command" file (I can double-click on my shell script file, and the script runs), instead of closing the window, while the file's code says "exit", what shows on the screen is: ... $l done logout [Process completed] ...and the window remains open. Does anyone know how to get a shell script to run, and then just automatically quit the Terminal window on completion? Thanks!

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• XSLT: How to escape square brackets in Urls

  - by ilariac

  I have a set of records from Solr where field[@name='url'] can have the following format: http://url/blabla/blabla.aspx?sv=[keyword%20keyword,%201] My understanding is that the square brackets denote an array syntax and I would like to use XSLT to remove the square brackets from all Urls. The reason for this is that I am using an Open URL resolver, which does not currently handle well those characters. The best option would be to strip the square brackets from all URLs before such resources are mediated by the Open URL resolver. There are cases where I have multiple occurrences of square brackets per Url. Can you please help me with this? Thanks for your help, I.

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• What are some good books on software testing/quality?

  - by mjh2007

  I'm looking for a good book on software quality. It would be helpful if the book covered: The software development process (requirements, design, coding, testing, maintenance) Testing roles (who performs each step in the process) Testing methods (white box and black box) Testing levels (unit testing, integration testing, etc) Testing process (Agile, waterfall, spiral) Testing tools (simulators, fixtures, and reporting software) Testing of embedded systems The goal here is to find an easy to read book that summarizes the best practices for ensuring software quality in an embedded system. It seems most texts cover the testing of application software where it is simpler to generate automated test cases or run a debugger. A book that provided solutions for improving quality in a system where the tests must be performed manually and therefore minimized would be ideal.

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• Visual Studio 2010 + ReSharper Not Working

  - by Joel

  I've installed ReSharper 5 on two installations of Visual Studio 2010 Professional. In both cases, ReSharper claims it has installed successfully - but Visual Studio doesn't recognize the extension. It doesn't show up in the Extensions Manager, doesn't appear in Help - About - Installed products, and can't be found anywhere else in the environment. I've tried install / uninstall of both Visual Studio and ReSharper, computer restarts, etc. Both machines have Visual Studio 2008 and ReSharper 5 works fine in these IDEs, and both machines are running Windows 7. I've found other people online with this issue, but no solutions. Anyone know how to fix this?

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• Finding the intersection of two vector equations.

  - by Matthew Mitchell

  I've been trying to solve this and I found an equation that gives the possibility of zero division errors. Not the best thing: v1 = (a,b) v2 = (c,d) d1 = (e,f) d2 = (h,i) l1: v1 + ?d1 l2: v2 + µd2 Equation to find vector intersection of l1 and l2 programatically by re-arranging for lambda. (a,b) + ?(e,f) = (c,d) + µ(h,i) a + ?e = c + µh b +?f = d + µi µh = a + ?e - c µi = b +?f - d µ = (a + ?e - c)/h µ = (b +?f - d)/i (a + ?e - c)/h = (b +?f - d)/i a/h + ?e/h - c/h = b/i +?f/i - d/i ?e/h - ?f/i = (b/i - d/i) - (a/h - c/h) ?(e/h - f/i) = (b - d)/i - (a - c)/h ? = ((b - d)/i - (a - c)/h)/(e/h - f/i) Intersection vector = (a + ?e,b + ?f) Not sure if it would even work in some cases. I haven't tested it. I need to know how to do this for values as in that example a-i. Thank you.

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• What should be done first: Code reviews or Unit tests?

  - by goldenmean

  Hello, If a developer implements code for some module and wants to get it reviewed. What should be the order : *First unit test the module after designing test cases for the module, debugging and fixing the bugs and then give the modified code for peer code review (Pros- Code to be reviewed is 'clean' to a good extent. Reduces some avoidable review comments and rework. Cons- Developer might spend large time debugging/fixing a bug which could have pointed/anticipated in peer code reviews) Or *First do the code review with peers and then go for unit testing. What are your thoughts/experience on this? I believe this approach for unit testing, code reviewing should be programming language agnostic, but it would be interesting to know otherwise(if applicable) with specific examples. -AD

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• Method hiding with interfaces

  - by fearofawhackplanet

  interface IFoo { int MyReadOnlyVar { get; } } class Foo : IFoo { int MyReadOnlyVar { get; set; } } public IFoo GetFoo() { return new Foo { MyReadOnlyVar = 1 }; } Is the above an acceptable way of implementing a readonly/immutable object? The immutability of IFoo can be broken with a temporary cast to Foo. In general (non-critical) cases, is hiding functionality through interfaces a common pattern? Or is it considered lazy coding? Or even an anti-pattern?

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• PNG Transparency Problems in IE8

  - by user138777

  I'm having problems with a transparent PNG image showing black dithered pixel artifacts around the edge of the non transparent part of the image. It only does this in Internet Explorer and it only does it from a Javascript file it is used in. Here's what I'm talking about... http://70.86.157.71/test/test3.htm (link now dead) ...notice the girl in the bottom right corner. She has artifacts around her in IE8 (I haven't tested it in previous versions of IE, but I'm assuming it probably does the same). It works perfectly in Firefox and Chrome. The image is loaded from a Javascript file to produce the mouseover effect. If you load the image all by itself, it works fine. Here's the image... http://70.86.157.71/test/consultant2.png Does anyone know how to fix this? The image was produced in Photoshop CS3. I've read things about removing the Gama, but that apparently was in previous versions of Photoshop and when I load it in TweakPNG, it doesn't have Gama. Please help!

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• Best Way to Generate Unique and consecutives numbers in Oracle

  - by RRUZ

  I need to generate unique and consecutive numbers (for use on an invoice), in a fast and reliable way. currently use a Oracle sequence, but in some cases generated numbers are not consecutive because of exceptions that may occur. I thought a couple of solutions to manage this problem, but neither of they convincing me. What solution do you recommend? Use a select max () SELECT MAX (NVL (doc_num, 0)) +1 FROM invoices Use a table to store the last number generated for the invoice. UPDATE docs_numbers SET last_invoice = last_invoice + 1 Another Solution?

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• Dynamic Spacer in ReportLab

  - by ptikobj

  I'm automatically generating a PDF-file with Platypus that has dynamic content. This means that it might happen that the length of the text content (which is directly at the bottom of the pdf-file) may vary. However, it might happen that a page break is done in cases where the content is too long. This is because i use a "static" spacer: s = Spacer(width=0, height=23.5*cm) as i always want to have only one page, I somehow need to dynamically set the height of the Spacer, so that it takes the "rest" of the space that is on the page as its height. Now, how do i get the "rest" of height that is left on my page?

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• Loop over a file and write the next line if a condition is met

  - by 111078384259264152964

  Having a hard time fixing this or finding any good hints about it. I'm trying to loop over one file, modify each line slightly, and then loop over a different file. If the line in the second file starts with the line from the first then the following line in the second file should be written to a third file. !/usr/bin/env python with open('ids.txt', 'rU') as f: with open('seqres.txt', 'rU') as g: for id in f: id=id.lower()[0:4]+'_'+id[4] with open(id + '.fasta', 'w') as h: for line in g: if line.startswith(''+ id): h.write(g.next()) All the correct files appear, but they are empty. Yes, I am sure the if has true cases. :-) "seqres.txt" has lines with an ID number in a certain format, each followed by a line with data. The "ids.txt" has lines with the ID numbers of interest in a different format. I want each line of data with an interesting ID number in its own file. Thanks a million to anyone with a little advice!

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• Binary Search Tree node removal

  - by doc

  I've been trying to implement a delete function for a Binary Search Tree but haven't been able to get it to work in all cases. This is my latest attempt: if(t->get_left() == empty) *t = *t->get_left(); else if(t->get_right() == empty) *t = *t->get_right(); else if((t->get_left() != empty) && (t->get_right() != empty)) { Node* node = new Node(t->get_data(), t->get_parent(), t->get_colour(), t->get_left(), t->get_right()); *t = *node; } t is a node and empty is just a node with nothing in it. I'm just trying to swap the values but I'm getting a runtime error. Any ideas? Thanks

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• Can a 32-bit RHEL4 userland work with a 64-bit kernel?

  - by James

  Is there a way to change an i386 RHEL4 machine to run an amd64 kernel, but ensure that it still builds software into same i386 binaries? On Debian this seems quite straightforward: just install an amd64 kernel (worst case, build one like this guy: http://www.debian-administration.org/users/jonesy/weblog/1) and prefix everything with "linux32". Then everything that considers uname -m will be unchanged, I just need to handle the few cases that consider uname -r. What is the Red Hat equivalent? Is the only way a full 64-bit installation on another disk and then chrooting back to the 32-bit system before anyone builds anything? (Even the best examples of that seem to be Debian-based.) Background: We make a large system that runs on (a variant of) i386 RHEL4. However, some of the larger RHEL build machines now have enough RAM that they might benefit from going 64-bit (for the kernel and maybe some of the bigger build steps). Our build system doesn't support cross-compilation.

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• ASP.NET cached aspx page & IIS logs

  - by Vishal Seth

  Hi guys, Is there any way to find out if ASP.Net runtime has served a cached copy of ASPX page or actually went through the page life cycle? Here is my problem: I'm seeing many entries in my IIS log files that were served successfully (200 OK). I've a corresponding logging code (Log4Net API) in the Session_Start and Application_BeginRequest() events that is logging every request to my DB with more details. I'm not seeing any corresponding entries in my SQL DB for some cases that should have been created by Log4Net code. Are there any logs available to find out if a cached copy was served by .NET worker process? Moreover, if my logging code would throw an exception, won't that show up as 500 in IIS logs? The code is on Windows 2008 Server, IIS 7.

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