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  • Nominal Attributes in LibSVM

    - by Chris S
    When creating a libsvm training file, how do you differentiate between a nominal attribute verses a numeric attribute? I'm trying to encode certain nominal attributes as integers, but I want to ensure libsvm doesn't misinterpret them as numeric values. Unfortunately, libsvm's site seems to have very little documentation. Pentaho's docs seem to imply libsvm makes this distinction, but I'm still not clear how it's made.

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  • What's the Easiest Way to Learn Programming?

    - by Chris
    If a friend of yours wanted to get into development and didn't have any experience, what would you suggest? What language/resources would you suggest to break into programming? With all of the technologies out right now and buzz words where should one even start explaining this stuff to people?

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  • Calculating Nearest Match to Mean/Stddev Pair With LibSVM

    - by Chris S
    I'm new to SVMs, and I'm trying to use the Python interface to libsvm to classify a sample containing a mean and stddev. However, I'm getting nonsensical results. Is this task inappropriate for SVMs or is there an error in my use of libsvm? Below is the simple Python script I'm using to test: #!/usr/bin/env python # Simple classifier test. # Adapted from the svm_test.py file included in the standard libsvm distribution. from collections import defaultdict from svm import * # Define our sparse data formatted training and testing sets. labels = [1,2,3,4] train = [ # key: 0=mean, 1=stddev {0:2.5,1:3.5}, {0:5,1:1.2}, {0:7,1:3.3}, {0:10.3,1:0.3}, ] problem = svm_problem(labels, train) test = [ ({0:3, 1:3.11},1), ({0:7.3,1:3.1},3), ({0:7,1:3.3},3), ({0:9.8,1:0.5},4), ] # Test classifiers. kernels = [LINEAR, POLY, RBF] kname = ['linear','polynomial','rbf'] correct = defaultdict(int) for kn,kt in zip(kname,kernels): print kt param = svm_parameter(kernel_type = kt, C=10, probability = 1) model = svm_model(problem, param) for test_sample,correct_label in test: pred_label, pred_probability = model.predict_probability(test_sample) correct[kn] += pred_label == correct_label # Show results. print '-'*80 print 'Accuracy:' for kn,correct_count in correct.iteritems(): print '\t',kn, '%.6f (%i of %i)' % (correct_count/float(len(test)), correct_count, len(test)) The domain seems fairly simple. I'd expect that if it's trained to know a mean of 2.5 means label 1, then when it sees a mean of 2.4, it should return label 1 as the most likely classification. However, each kernel has an accuracy of 0%. Why is this? On a side note, is there a way to hide all the verbose training output dumped by libsvm in the terminal? I've searched libsvm's docs and code, but I can't find any way to turn this off.

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  • Precomputed Kernels with LibSVM in Python

    - by Lyyli
    I've been searching the net for ~3 hours but I couldn't find a solution yet. I want to give a precomputed kernel to libsvm and classify a dataset, but: How can I generate a precomputed kernel? (for example, what is the basic precomputed kernel for Iris data?) In the libsvm documentation, it is stated that: For precomputed kernels, the first element of each instance must be the ID. For example, samples = [[1, 0, 0, 0, 0], [2, 0, 1, 0, 1], [3, 0, 0, 1, 1], [4, 0, 1, 1, 2]] problem = svm_problem(labels, samples) param = svm_parameter(kernel_type=PRECOMPUTED) What is a ID? There's no further details on that. Can I assign ID's sequentially? Any libsvm help and an example of precomputed kernels really appreciated.

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  • What should programmers practice every day?

    - by Jacinda S
    Musicians practice scales, arpeggios, etc. every day before they begin playing "real" music. The top sports players spend time every day practicing fundamentals like dribbling before playing the "real" game. Are there fundamentals that programmers should practice every day before writing "real" code?

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  • Forth: free video tutorials?

    - by Peter Mortensen
    Can you recommend any free Forth video tutorials (except for following) ? The only one I know of is Samuel A. Falvo's excellent "Over The Shoulder Episode 1: Text Preprocessing in Forth". MPEG. 102 MB. There are also videos from the annual Forth Day, but I don't consider those to be tutorials. (Unfortunately Forth is, like R, C, C++, Java, C#, D, COM, .NET, F# and Frontier, an unspecific search term. Search tip for Forth: qualify it with "ans" - as in ANS Forth, the ANSI Forth Standard.) Accumulated based on answers and other information: Introductions to Forth Forth. By Ben Stiglitz. At RubyConf 2008 Orlando Florida, U.S.A. 13 min 35 secs. 32 MB. MP4. Advanced Over The Shoulder Episode 1: Text Preprocessing in Forth. By Samuel A. Falvo. 1 h 06 min 25 secs. 102 MB. MPEG.

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  • Where do I find a good explanation of Javascript-ese

    - by tzenes
    I realize that title may require explanation. The language I first learned was C, and it shows in all my programs... even those not written in C. For example, when I first learned F# I wrote my F# programs like C programs. It wasn't until someone explained the pipe operator and mapping with anonymous functions that I started to understand the F#-ese, how to write F# like a F# programmer and not a C programmer. Now I've written a little javascript, mostly basic stuff using jquery, but I was hoping there was a good resource where I could learn to write javascript programs like a javascript programmer.

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  • Issues in Convergence of Sequential minimal optimization for SVM

    - by Amol Joshi
    I have been working on Support Vector Machine for about 2 months now. I have coded SVM myself and for the optimization problem of SVM, I have used Sequential Minimal Optimization(SMO) by Mr. John Platt. Right now I am in the phase where I am going to grid search to find optimal C value for my dataset. ( Please find details of my project application and dataset details here http://stackoverflow.com/questions/2284059/svm-classification-minimum-number-of-input-sets-for-each-class) I have successfully checked my custom implemented SVM`s accuracy for C values ranging from 2^0 to 2^6. But now I am having some issues regarding the convergence of the SMO for C 128. Like I have tried to find the alpha values for C=128 and it is taking long time before it actually converges and successfully gives alpha values. Time taken for the SMO to converge is about 5 hours for C=100. This huge I think ( because SMO is supposed to be fast. ) though I`m getting good accuracy? I am screwed right not because I can not test the accuracy for higher values of C. I am actually displaying number of alphas changed in every pass of SMO and getting 10, 13, 8... alphas changing continuously. The KKT conditions assures convergence so what is so weird happening here? Please note that my implementation is working fine for C<=100 with good accuracy though the execution time is long. Please give me inputs on this issue. Thank You and Cheers.

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  • building a backend for generating webquests with rails

    - by buk
    hello, i want to learn rails and as a project to learn rails i came across webquests. what a webquest is is clearly written here1 and this is a example how a webquest look like. i started with script/generate nifty_scaffold introduction index and repeat this for every section like task , Process, Evaluation and so on. but i dont think thats the right way because i have a lot of code for the same thing. on the other side i am more flexible on designing views or controllers instead of having only one controller foer all pages. i am not asking here to get code. i am asking who to "build" such a backend where you can click on "New Webquest" a form comes up and you can enter all the text who belongs to the topic. maybee i can add some drawings later. i hope anyone can show me how to do that. or post me some links or some rtfms :D regards, buk

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  • Java equivalent to VS solution file

    - by Chris
    I'm a C# guy trying to learn Java. I understand the syntax and the basic architecture of the Java platform, and have no problem doing smaller projects myself, but I'd really like to be able to download some open source projects to learn from the work of others. However, I'm running into a stumbling block that I can't seem to find any information on. When I download an open source .NET project, I can open the .sln file with visual studio and everything just loads. Sure, there's occasionally a missing reference or something, but there's really very little configuration required to get things going. I'm not sensing the same ease of use with Java. I'm using eclipse at the moment, and it feels like for every project I have to create a brand new Eclipse project using "create from existing source", and almost nothing compiles properly without significant reconfiguration. In the case of web projects, it's even worse, because Eclipse doesn't appear to support creating a web project from existing source. I have to create a standard Java project from source, then then apparently modify the project file to include the bindings for the web toolkit stuff to work properly. Assuming I want to be able to contribute to a project later on, I shouldn't have to be making such drastic changes to the file structure to get my IDE to a workable state. What am I missing?

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  • what is the best way to generate fake data for classification problem ?

    - by Berkay
    i'm working on a project and i have a subset of user's key-stroke time data.This means that the user makes n attempts and i will use these recorded attempt time data in various kinds of classification algorithms for future user attempts to verify that the login process is done by the user or some another person. (Simply i can say that this is biometrics) I have 3 different times of the user login attempt process, ofcourse this is subset of the infinite data. until now it is an easy classification problem, i decided to use WEKA but as far as i understand i have to create some fake data to feed the classification algorithm. can i use some optimization algorithms ? or is there any way to create this fake data to get min false positives ? Thanks

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  • What really happens when I use varchar(10) in the sqlite command-line shell?

    - by romandas
    I'm messing around with SQLite for the first time by working through some of the SQLite documentation. In particular, I'm using Command Line Shell For SQLite and the SoupToNuts SQLite Tutorial on Sourceforge. According to the SQLite datatype documentation, there are only 5 datatypes in SQLite. However, in the two tutorial documents above, I see where the authors use commands such as create table tbl1(one varchar(10), two smallint); or create table t1 (t1key INTEGER PRIMARY KEY,data TEXT,num double,timeEnter DATE); which contain datatypes that aren't listed by SQLite, yet these commands work just fine. Additionally, when I ran .dump to see the SQL statements, these datatype specifications are preserved. So, what gives? Does SQLite keep a reference for any datatype specified in the SQL yet converts it behind the scenes to one of its 5 datatypes? Or is there something else I'm missing?

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  • Bag of words Classification

    - by AlgoMan
    I need find words training words and their classification. Simple classification such as . Sports Entertainment and Politics things like that. Where Can i find the words and their classifications. I know many universities have done Bag of words classifications. Is there any repository of training examples ?

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  • learn dbms online

    - by siva
    Hi I want to learn DBMS including the concepts of complex SQL writing and normalisation and other stuff. Can anyone please help me to find some useful online resources.....

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  • How can this C and PHP programmer learn Ruby and Rails?

    - by Winston
    I came from a C, php and bash background, it was easy to learn because they all have the same C structure, which I can associate with what I already know. Then 2 years ago I learned Python and I learned it quite well, Python is easier for me to learn than Ruby. Then since last year, I was trying to learn Ruby, then Rails, and I admit, until now I still couldn't get it, the irony is that those are branded as easy to learn, but for a seasoned programmer like me, I just couldn't associate it with what I learned before, I have 2 books on both Ruby and Rails, and when I'm reading it nothing is absorbed into my mind, and I'm close to giving up... In ruby, I'm having a hard time grasping the concepts of blocks, and why there's @variables that can be accessed by other functions, and what does $variable and :variable do? And in Rails, why there's function like this_is_another_function_that_do_this, so thus ruby, is it just a naming convention or it's auto-generated with thisvariable _can_do_this_function. I'm still puzzled that where all those magic concepts and things came from? And now, 1 year of trying and absorbing, but still no progress... Edit: To summarize: How can I learn about blocks, and how can it be related to concepts from PHP/C? Variables, what does does it mean when a variable is prefixed with: @ $ : "Magic concepts", suchs as rails declarations of Records, what happens behind the scenes when I write has_one X OK so, bear with me with my confusion, at least I'm honest with myself, and it's over a year now since I first trying to learn ruby, and I'm not getting younger.. so I learned this in Bash/C/PHP solve_problem($problem) { if [ -e $problem == "trivial" ]; then write_solution(); else breakdown_problem_into_N_subproblems(\; define_relationship_between_subproblems; for i in $( command $each_subproblem ); do solve_problem $i done fi } write_solution(problem) { some_solution=$(command <parameters> "input" | command); command | command $some_solution > output_solved_problem_to_file } breakdown_problem_into_N_subproblems($problems) { for i in $problems; do command $i | command > i_can_output_a_file_right_away done } define_relationship_between_subproblems($problems) { if [ -e $problem == "relationship" ]; then relationship=$(command; command | command; command;) elsif [ -e $problem == "another_relationship" ]; relationship=$(command; command | command; command;) fi } In C/PHP is something like this solve_problem(problem) { if (problem == trivial) write_solution; else { breakdown_problem_into_N_subproblems; define_relationship_between_subproblems; for (each_subproblem) solve_problems(subproblem); } } And now, I just couldn't connect the dots with Ruby, |b|{ blocks }, using @variables, :variables, and variables_with_this_things..

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  • Statistical approach to chess?

    - by Chinmay Kanchi
    Reading about how Google solves the translation problem got me thinking. Would it be possible to build a strong chess engine by analysing several million games and determining the best possible move based largely (completely?) on statistics? There are several such chess databases (this is one that has 4.5 million games), and one could potentially weight moves in identical (or mirrored or reflected) positions using factors such as the ratings of the players involved, how old the game is (to factor in improvements in chess theory) etc. Any reasons why this wouldn't be a feasible approach to building a chess engine?

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  • Kohonen SOM Maps: Normalizing the input with unknown range

    - by S.N
    According to "Introduction to Neural Networks with Java By Jeff Heaton", the input to the Kohonen neural network must be the values between -1 and 1. It is possible to normalize inputs where the range is known beforehand: For instance RGB (125, 125, 125) where the range is know as values 0 and 255: 1. Divide by 255: (125/255) = 0.49 (0.49,0.49,0.49) 2. Multiply by two and subtract one: ((0.49*2)-1)=-0.02 (-0.02,-0.02,-0.02) The question is how can we normalize the input where the range is unknown like our height or weight. Also, some other papers mention that the input must be normalized to the values between 0 and 1. Which is the proper way, "-1 and 1" or "0 and 1"?

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  • getting started with nosql

    - by radi
    hi , i am new to nosql world i know sql and rdbms very well , i want to get start with nosql so i need to know : where i can start read about nosql (books , online tutorials )? what is the most simple nosql engine i can start with (i am using java)? thanks .

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  • What are the primitive Forth operators?

    - by Barry Brown
    I'm interested in implementing a Forth system, just so I can get some experience building a simple VM and runtime. When starting in Forth, one typically learns about the stack and its operators (DROP, DUP, SWAP, etc.) first, so it's natural to think of these as being among the primitive operators. But they're not. Each of them can be broken down into operators that directly manipulate memory and the stack pointers. Later one learns about store (!) and fetch (@) which can be used to implement DUP, SWAP, and so forth (ha!). So what are the primitive operators? Which ones must be implemented directly in the runtime environment from which all others can be built? I'm not interested in high-performance; I want something that I (and others) can learn from. Operator optimization can come later. (Yes, I'm aware that I can start with a Turing machine and go from there. That's a bit extreme.) Edit: What I'm aiming for is akin to bootstrapping an operating system or a new compiler. What do I need do implement, at minimum, so that I can construct the rest of the system out of those primitive building blocks? I won't implement this on bare hardware; as an educational exercise, I'd write my own minimal VM.

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