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  • Confusion Matrix with number of classified/misclassified instances on it (Python/Matplotlib)

    - by Pinkie
    I am plotting a confusion matrix with matplotlib with the following code: from numpy import * import matplotlib.pyplot as plt from pylab import * conf_arr = [[33,2,0,0,0,0,0,0,0,1,3], [3,31,0,0,0,0,0,0,0,0,0], [0,4,41,0,0,0,0,0,0,0,1], [0,1,0,30,0,6,0,0,0,0,1], [0,0,0,0,38,10,0,0,0,0,0], [0,0,0,3,1,39,0,0,0,0,4], [0,2,2,0,4,1,31,0,0,0,2], [0,1,0,0,0,0,0,36,0,2,0], [0,0,0,0,0,0,1,5,37,5,1], [3,0,0,0,0,0,0,0,0,39,0], [0,0,0,0,0,0,0,0,0,0,38] ] norm_conf = [] for i in conf_arr: a = 0 tmp_arr = [] a = sum(i,0) for j in i: tmp_arr.append(float(j)/float(a)) norm_conf.append(tmp_arr) plt.clf() fig = plt.figure() ax = fig.add_subplot(111) res = ax.imshow(array(norm_conf), cmap=cm.jet, interpolation='nearest') cb = fig.colorbar(res) savefig("confmat.png", format="png") But I want to the confusion matrix to show the numbers on it like this graphic (the right one): http://i48.tinypic.com/2e30kup.jpg How can I plot the conf_arr on the graphic?

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  • T-SQL Re-Assigning Order Numbering

    - by Meltdown
    Say I have a table with a field called "ordernum" that denotes the order of a given set of rows. Now imagine that I delete one of these rows. What type of query would work best for re-assigning the order numbers so that they remain sequential? Here's an example: id group_id name ordernum active --------------------------------------------------- 0_____0______'Name1'___5__true 1_____0______'Name2'___4__true 2_____0______'Name3'___3__true 3_____1______'Name4'___2__true 4_____1______'Name5'__1__true 5_____1______'Name6'__NULL___false Now if I deleted the column with id='4' how would I reset the values in the 'ordernum' field for that specific group? Is this even possible? Or if I added a new row. (The first time the rows are created they are sorted by date, but then the user has the option to set the order himself.) In my table design I have a column 'active' boolean. If 'active' is set to false, then 'ordernum' is set to NULL. Otherwise it should be given an order number.

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  • Embedding a YouTube Video Based on a PHP Variable

    - by jeffpm
    I have a website that I am creating for a class project. The website shows information about bands (which is stored in a mysql database). I am trying to spruce up the site a bit, and I would like to embed a YouTube video based on the band's name. Say, for instance, I have "Led Zeppelin" stored in my database. How can I take a PHP variable containing "Led Zeppelin", search YouTube using that variable, find a random video, and then embed that in the website? From the research I've done, it seems you can only embed YouTube videos if you know the exact address of the video. Thanks!

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  • Unique identifiers for users

    - by Christopher McCann
    If I have a table of a hundred users normally I would just set up an auto-increment userID column as the primary key. But if suddenly we have a million users or 5 million users then that becomes really difficult because I would want to start becoming more distributed in which case an auto-increment primary key would be useless as each node would be creating the same primary keys. Is the solution to this to use natural primary keys? I am having a real hard time thinking of a natural primary key for this bunch of users. The problem is they are all young people so they do not have national insurance numbers or any other unique identifier I can think of. I could create a multi-column primary key but there is still a chance, however miniscule of duplicates occurring. Does anyone know of a solution? Thanks

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  • SQLServer 2008 Pivot

    - by Mitch
    I need to show some information in a graph, the data is held in a SQL Server 2008 table. The graph is expecting 2 columns, one for QuestionNumber and the other for Score. The table containing the data has column names that correspond to the question numbers ie A1, A2, A3, A4, B1, B2, B3, B4, C1, C2. Each question is given a score of 1 to 5. I need to show a graph where the X axis shows A1, A2, A3 etc and the Y axis shows the score. I'm thinking I somehow need to rotate the data to achive this, but I'm not sure how. Maybe a different technique can acheive this rather that a Rotate, so I'm open to any ideas.

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  • How do I compute the approximate entropy of a bit string?

    - by dreeves
    Is there a standard way to do this? Googling -- "approximate entropy" bits -- uncovers multiple academic papers but I'd like to just find a chunk of pseudocode defining the approximate entropy for a given bit string of arbitrary length. (In case this is easier said than done and it depends on the application, my application involves 16,320 bits of encrypted data (cyphertext). But encrypted as a puzzle and not meant to be impossible to crack. I thought I'd first check the entropy but couldn't easily find a good definition of such. So it seemed like a question that ought to be on StackOverflow! Ideas for where to begin with de-cyphering 16k random-seeming bits are also welcome...) See also this related question: http://stackoverflow.com/questions/510412/what-is-the-computer-science-definition-of-entropy

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  • OpenID and Authlogic - login and password?

    - by skrat
    How can I get rid of validation messages telling me that: Login is too short (minimum is 3 characters) Login should use only letters, numbers, spaces, and .-_@ please. Password is too short (minimum is 4 characters) Password confirmation is too short (minimum is 4 characters) this happens even before map_openid_registration is called, thus not giving me any chance to fill login with something from returned registration Hash. I would like to have OpenID auto-registration (on login) without requiring user to supply login/password. I also won't make this fields "not required" or "not validated", since I still need them with old school login/password registration. Thank you

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  • Essential skills of a Data Scientist

    - by harshsinghal
    I would like to know more about the relevant skills in the arsenal of a Data Scientist, and with new technologies coming in every day, how one picks and chooses the essentials. A few ideas germane to this discussion: Knowing SQL and the use of a DB such as MySQL, PostgreSQL was great till the advent of NoSql and non-relational databases. MongoDB, CouchDB etc. are becoming popular to work with web-scale data. Knowing a stats tool like R is enough for analysis, but to create applications one may need to add Java, Python, and such others to the list. Data now comes in the form of text, urls, multi-media to name a few, and there are different paradigms associated with their manipulation. What about cluster computing, parallel computing, the cloud, Amazon EC2, Hadoop ? OLS Regression now has Artificial Neural Networks, Random Forests and other relatively exotic machine learning/data mining algos. for company Thoughts?

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  • Do I need to use decimal places when using floats? Is the "f" suffix necessary?

    - by Paulo Fierro
    I've seen several examples in books and around the web where they sometimes use decimal places when declaring float values even if they are whole numbers, and sometimes using an "f" suffix. Is this necessary? For example: [UIColor colorWithRed:0.8 green:0.914 blue:0.9 alpha:1.00]; How is this different from: [UIColor colorWithRed:0.8f green:0.914f blue:0.9f alpha:1.00f]; Does the trailing "f" mean anything special? Getting rid of the trailing zeros for the alpha value works too, so it becomes: [UIColor colorWithRed:0.8 green:0.914 blue:0.9 alpha:1]; So are the decimal zeros just there to remind myself and others that the value is a float? Just one of those things that has puzzled me so any clarification is welcome :)

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  • How do I randomly fill an array in Java?

    - by Kat
    I'm writing a program that creates a 2D array from a integer n. I then have to fill the array with values from 1 to the n*n array size and check to see if it is a magic square. The way I am doing it now fills the array in order from 1 to n*n array size. How can I make that random? My code: System.out.print("Enter an whole number: "); int n = scan.nextInt(); int [][] magic = new int [n][n]; for (int row = 0; row < magic.length; row++) { for(int col = 0; col < magic[row].length; col++) magic[row][col] = ((row * n) + 1) + col; }

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  • Context-sensitive grammar for specific language

    - by superagio
    How can I construct a grammar that generates this language? Construct a grammar that generates L: L = {a^n b^m c^k|k>n, k>m} I believe my productions should go along this lines: S-> ABCC A-> a|aBC|BC B-> b|bBC C-> c|Cc CB->BC The idea is to start with 2 c and keep always one more c, and then with C-c|Cc ad as much c as i want. How can my production for C remember the numbers of m and n.

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  • Easiest way to find the correct kademlia bucket

    - by Martin
    In the Kademlia protocol node IDs are 160 bit numbers. Nodes are stored in buckets, bucket 0 stores all the nodes which have the same ID as this node except for the very last bit, bucket 1 stores all the nodes which have the same ID as this node except for the last 2 bits, and so on for all 160 buckets. What's the fastest way to find which bucket I should put a new node into? I have my buckets simply stored in an array, and need a method like so: Bucket[] buckets; //array with 160 items public Bucket GetBucket(Int160 myId, Int160 otherId) { //some stuff goes here } The obvious approach is to work down from the most significant bit, comparing bit by bit until I find a difference, I'm hoping there is a better approach based around clever bit twiddling. Practical note: My Int160 is stored in a byte array with 20 items, solutions which work well with that kind of structure will be preferred.

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  • How do quickly search through a .csv file in Python

    - by Baldur
    I'm reading a 6 million entry .csv file with Python, and I want to be able to search through this file for a particular entry. Are there any tricks to search the entire file? Should you read the whole thing into a dictionary or should you perform a search every time? I tried loading it into a dictionary but that took ages so I'm currently searching through the whole file every time which seems wasteful. Could I possibly utilize that the list is alphabetically ordered? (e.g. if the search word starts with "b" I only search from the line that includes the first word beginning with "b" to the line that includes the last word beginning with "b") I'm using import csv. (a side question: it is possible to make csv go to a specific line in the file? I want to make the program start at a random line) Edit: I already have a copy of the list as an .sql file as well, how could I implement that into Python?

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  • Prim's MST algorithm implementation with Java

    - by user1290164
    I'm trying to write a program that'll find the MST of a given undirected weighted graph with Kruskal's and Prim's algorithms. I've successfully implemented Kruskal's algorithm in the program, but I'm having trouble with Prim's. To be more precise, I can't figure out how to actually build the Prim function so that it'll iterate through all the vertices in the graph. I'm getting some IndexOutOfBoundsException errors during program execution. I'm not sure how much information is needed for others to get the idea of what I have done so far, but hopefully there won't be too much useless information. This is what I have so far: I have a Graph, Edge and a Vertex class. Vertex class mostly just an information storage that contains the name (number) of the vertex. Edge class can create a new Edge that has gets parameters (Vertex start, Vertex end, int edgeWeight). The class has methods to return the usual info like start vertex, end vertex and the weight. Graph class reads data from a text file and adds new Edges to an ArrayList. The text file also tells us how many vertecis the graph has, and that gets stored too. In the Graph class, I have a Prim() -method that's supposed to calculate the MST: public ArrayList<Edge> Prim(Graph G) { ArrayList<Edge> edges = G.graph; // Copies the ArrayList with all edges in it. ArrayList<Edge> MST = new ArrayList<Edge>(); Random rnd = new Random(); Vertex startingVertex = edges.get(rnd.nextInt(G.returnVertexCount())).returnStartingVertex(); // This is just to randomize the starting vertex. // This is supposed to be the main loop to find the MST, but this is probably horribly wrong.. while (MST.size() < returnVertexCount()) { Edge e = findClosestNeighbour(startingVertex); MST.add(e); visited.add(e.returnStartingVertex()); visited.add(e.returnEndingVertex()); edges.remove(e); } return MST; } The method findClosesNeighbour() looks like this: public Edge findClosestNeighbour(Vertex v) { ArrayList<Edge> neighbours = new ArrayList<Edge>(); ArrayList<Edge> edges = graph; for (int i = 0; i < edges.size() -1; ++i) { if (edges.get(i).endPoint() == s.returnVertexID() && !visited(edges.get(i).returnEndingVertex())) { neighbours.add(edges.get(i)); } } return neighbours.get(0); // This is the minimum weight edge in the list. } ArrayList<Vertex> visited and ArrayList<Edges> graph get constructed when creating a new graph. Visited() -method is simply a boolean check to see if ArrayList visited contains the Vertex we're thinking about moving to. I tested the findClosestNeighbour() independantly and it seemed to be working but if someone finds something wrong with it then that feedback is welcome also. Mainly though as I mentioned my problem is with actually building the main loop in the Prim() -method, and if there's any additional info needed I'm happy to provide it. Thank you. Edit: To clarify what my train of thought with the Prim() method is. What I want to do is first randomize the starting point in the graph. After that, I will find the closest neighbor to that starting point. Then we'll add the edge connecting those two points to the MST, and also add the vertices to the visited list for checking later, so that we won't form any loops in the graph. Here's the error that gets thrown: Exception in thread "main" java.lang.IndexOutOfBoundsException: Index: 0, Size: 0 at java.util.ArrayList.rangeCheck(Unknown Source) at java.util.ArrayList.get(Unknown Source) at Graph.findClosestNeighbour(graph.java:203) at Graph.Prim(graph.java:179) at MST.main(MST.java:49) Line 203: return neighbour.get(0); in findClosestNeighbour() Line 179: Edge e = findClosestNeighbour(startingVertex); in Prim()

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  • Monotone-increasing Version Number based on Mercurial Commits

    - by Isaac
    When I was using subversion for the code for an application, I could append a period and the result of svnversion to the version number to create a unique and monotone-increasing version number and also be guaranteed that any check-out of the same revision of the code would generate the same version number. In Mercurial, because revision numbers are not necessarily consistent across clones, the local revision number is not suitable. The hash is appropriately unique and consistent, but does not create a number that is monotone-increasing. How can I generate a suitable number to append to the version number based on the Mercurial repository commits?

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  • Setting a VCProject property to default

    - by Ofek Shilon
    I'm trying some VS2005 IDE macros to modify a large amount of projects (~80) within a solution. Some of the properties I wish to set do expose a programmatic interface to 'default', but many others do not. Is there a generic way to set such properties to their default? (eventually meaning erasing them from the .vcproj file) Simplified example, setting some random properties: Sub SetSomeProps() Dim prj As VCProject Dim cfg As VCConfiguration Dim toolCompiler As VCCLCompilerTool Dim toolLinker As VCLinkerTool Dim EnvPrj As EnvDTE.Project For Each EnvPrj In DTE.Solution.Projects prj = EnvPrj.Object cfg = prj.Configurations.Item(1) toolLinker = cfg.Tools("VCLinkerTool") If toolLinker IsNot Nothing Then ' Some tool props that expose a *default* interface' toolLinker.EnableCOMDATFolding = optFoldingType.optFoldingDefault toolLinker.OptimizeReferences = optRefType.optReferencesDefault toolLinker.OptimizeForWindows98 = optWin98Type.optWin98Default End If toolCompiler = cfg.Tools("VCCLCompilerTool") If toolCompiler IsNot Nothing Then ' How to set it to default? (*erase* the property from the .vcproj)' toolCompiler.CallingConvention = callingConventionOption.callConventionCDecl toolCompiler.WholeProgramOptimization = False toolCompiler.Detect64BitPortabilityProblems = False End If Next End Sub Any advice would be appreciated.

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  • Where to find great proxy servers for testing GeoIP services?

    - by Andreas
    We would like to test a GeoIP-Service. Therefore we need to go to the site with an IP from another country. There are a lot of free proxy lists like http://nntime.com/proxy-country/ The problem with them is, that only the CoDeen-Proxies are working. But with CoDeen you can't select your country of origin (the same as with TOR). You get redirected to a random proxy in the network. Where to find good proxy server for testing the GeoIP Services? Free proxy servers would be great, but if they cost something small that doesn't matter.

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  • How do you diagnose a 500 error on Heroku when there is no error message in the logs?

    - by lala
    I have a Rails app on Heroku that is serving 500 errors at random intervals. Web pages will display "Internal server error" in plain text, instead of the usual "We're sorry. Something went wrong." page. When I refresh the page, it works fine. The logs don't show me an error message, just » 14:20:34.107 2013-10-11 12:20:33.763690+00:00 heroku router - - at=info method=HEAD path=/ host=www.mydomain.com fwd="184.73.237.85/ec2-184-73-237-85.compute-1.amazonaws.com" dyno=web.1 connect=1ms service=63ms status=200 bytes=0 » 14:21:03.957 2013-10-11 12:21:03.561867+00:00 heroku router - - at=info method=GET path=/ host=www.mydomain.com fwd="50.112.95.211/ec2-50-112-95-211.us-west-2.compute.amazonaws.com" dyno=web.1 connect=0ms service=1ms status=500 bytes=21 Support has told me to look at request queuing in New Relic, but New Relic only shows a big red mark saying the server is down (even though the site works fine when refreshed). With no error messages, I'm at a loss for how to diagnose this issue.

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  • Can an app use the clipboard for its own purposes? (read: who owns the clipboard?)

    - by eran
    In PowerBuilder's IDE, the code autocomplete feature uses the clipboard to communicate the completed text to the code window. By doing so, it overrides whatever was stored on the clipboard before. So, if you had the winning numbers of the next lottary stored on your clipboard, and you used the autocomplete to turn m_goodfor into m_goodfornothing, you've just lost your only chance of ever getting rich, and you're left with nothing on your clipboard. Features like that are the reason I hate software. It looks like it was implemented by some intern that noone was looking after. However, there's also a chance I got all worked up for nothing, and making such use of the clipboard is absolutely legit. So, can an app use the clipboard for its own purposes? Who is considered the owner of the clipboard? (Bonus votes to whoever puts himself in place of the feature's programmer, and provides some reasoning for this being done on purpose, assuming the users would actually benefite from it)

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  • prevent multiple login with same login credentials in php

    - by shinod
    My website has premium videos, for which users have to pay to watch it. I am sending a random user name and password to the user's email id when the payment is completed. Then I want to assure no more than one user use that login credentials simultaneously. For that I use a login_status column in database table with login credentials and change it to 1 when one user login and change to 0 when user log out. But the problem is, if the user close browser or network connection loss may happened will not update database. Then login_will be 1 undefinitely and no one can use that login credentials again. Is there any idea to accomplish my task?

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  • WPF ListView.CurrentChanged too fast for binding

    - by matt
    My case: MVVM ListView+Details(custom UserControl) List bound to MV.Items (IsSynchronizedWithCurrent=true) Details bound to MV.Items.Current MV.Items.Count == 100 about 0.2sec to read details (lazy mode) When I hold the down arrow on the list, very strange things happen: list items order change current changes in the random order CPU usage drastically increments and eventually all hangs. I've read some post that one should start the timer or run handler in the background, but I am not able to do that, since all the binding WPF does for me. Is there some way to instruct the binding in my DetailsControl, to wait a while before accepting CurrentItem? Or should I just resign from the clean solution and write custom code in my MV to handle that?

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  • how to read an address in multiple formats like google maps

    - by ratan
    notice that on google maps you can input the address any way you like. as long as it is a valid address...google maps will read it. In some ruby book I had seen code snippet for something like this, but with phone numbers. Any ideas how this could be done for addresses? in language of your choice. EDIT: i dont care about a "valid" address. I just want to parse an address. so that 123 fake street, WA, 34223 would be an address and so will 123 fake street WA 34223

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  • Is there a way in Sphinx/Pygments to emphasize one or more lines of code in literal includes?

    - by Casey
    In some sphinx docs I am writing, I am including code samples from an ancillary file like so: .. literalinclude:: mymodule.py :pyobject: MyClass :linenos: This particular doc is a tutorial, where the classes are build up step by step. What I would like to do is include the entire class or a single method, and emphasize only the lines of interest to that section. That way the context is preserved but the interesting parts are obvious at a glance. Right now I have resorted to just referring to line numbers in the text, which is ok, but far from ideal. Looking at the docs and code for sphinx and pygments I don't find an obvious way to do this. I'm not opposed to patching them or doing something tricky in conf.py, but I wondered if anyone had solved this.

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  • Compact a given array problem

    - by Bragaadeesh
    Dont know whether this is a duplicate, but this was an interview question asked to me. Given an array of random numbers and -1 placed inbetween, I have to compact the array meaning all the -1s are to be replaced and the final output should be the last valid index with the fresh array. For example. Input: 3 4 -1 -1 -1 5 8 -1 8 Output: 3 4 5 8 8 5 8 -1 8 and last valid index is 4 Input: -1 -1 -1 -1 -1 2 Output: 2 -1 -1 -1 -1 2 and last valid index is 0 Input: -1 -1 -1 3 3 3 Output: 3 3 3 3 3 3 and last valid index is 2 You should not swap the values just the last valid index along with the array is enough to decipher the non negative values.

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  • Numeric comparison difficulty in R

    - by Matt Parker
    I'm trying to compare two numbers in R as a part of a if-statement condition: (a-b) >= 0.5 In this particular instance, a = 0.58 and b = 0.08... and yet (a-b) >= 0.5 is false. I'm aware of the dangers of using == for exact number comparisons, and this seems related: (a - b) == 0.5) is false, while all.equal((a - b), 0.5) is true. The only solution I can think of is to have two conditions: (a-b) > 0.5 | all.equal((a-b), 0.5). This works, but is that really the only solution? Should I just swear off of the = family of comparison operators forever?

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