LIBSVM is an integrated software library for support vector machines, performing support vector classification, (C-SVC, nu-SVC), regression (epsilon-SVR, nu-SVR) and distribution estimation (one-class SVM)

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Selecting most realistic C and g params after gridsearch

I just ran an extended SVC gridsearch in libsvm on about 9000 multi-dimensional vectors representing a time series. Here are the highest scoring results: ...
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26 views

About grid search to find the best value of C

I know when I want to find the best values of C and gamma, I should use grid-search. But in my case I want to find just the best value of C. So, this is called a line-search. Is there any function ...
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18 views

How to retrieve the prediction equation in R?

I have developed a prediction model prototype in R. The model uses Support Vector Regression to predict. But I need to develop the entire solution in Visual C++ for a real life implementation. I ...
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Pattern recognition training base division

1) A dataset (100 samples, 10 classes, 8 chars each) was multiclassed obtaining a good accuracy with an external dataset. 2) The same dataset was divided in half (50 samples, 5 classes, 8 chars each) ...
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50 views

Linear SVM prediction time is scaling in an unexpected manner based on training data

I'm using LIBSVM to do some training as it was recommended by Andrew Ng and is used under the hood in SciKit Learn. LIBSVM is doing something different than what I expect though: My beliefs are as ...
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28 views

Instance weighing in libsvm/liblinear

I often use the instance weights with Libsvm for classification problems. http://www.csie.ntu.edu.tw/~cjlin/libsvmtools/#weights_for_data_instances Does anyone know the details of the algorithm that ...
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35 views

How to format multi-row time series data for LIBSVM regression

I would have expected this to be covered in detail by the LIBSVM tutorial but after hours of wasting time googling for answers I've had to throw in the towel. What I am trying to do is rather trivial ...
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6 views

libsvm with diffrent count of Keypoints [migrated]

I would like to use libsvm for a keypoint detection algorithm. Each keypoint has 36 features, but each sample of an Object has a diffrent count of keypoints... Is it even possible to train with ...
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21 views

Examine SVM result by plotting histogram of decision values of training samples

I'm working for object detection(computer vision) and have some problems in SVM training. My training configuration is as below. Balanced training set (positive 3998/ negative 3998) The dimension of ...
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19 views

How should I do a grid search for the gamma in SVM?

I know that you can do a grid search for the C parameter (-c) in libSVM by going through value that go from 10^-5 to 10^5. How should I go about finding the optimal epsilon parameter (-p) ? Is ...
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32 views

different feature types for classification

There has a data set with several features. One feature is of the type of continuous numerical values; another feature is of the type of categorical values, such as A, B and C. If I want to build a ...
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32 views

Find linear SVM feature weights using libsvm

I'm trying to use linear SVM to do some feature selection. I'm using libsvm, but I cannot figure out how to find feature weights. The model file created looks something like this: ...
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35 views

Parameter optimization of SVM

Currently I am using SVM to perform some classification task. I use libSVM with Matlab interface. From the practical guide of SVM (Link), we know that there are two parameters need to be tuned, namely ...
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67 views

Assigning even partitions for Cross-Validation

This is a very basic question about cross-validation. Say that I have a sample size of 2901(or any difficult to divide number). How do I split this up into equal partitions (other than n=1)? And how ...
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45 views

Kernel selection using SVM for keyword frequency classification

I have data in Weka .arff multiple-class training and testing data representing daily word frequencies in RSS feeds as follows: ...
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43 views

Interpretation C value in linear SVM

My C value is very low (close to 0). Does this mean that my feature (dimensions) have no real separative (and thus predictive) value? (As the SVM basically chooses to ignore the training data ...
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66 views

Simple SVM Question

For a linear SVM, the documentation tells me the formula is: $$ \frac{1}{2}w^Tw+C\sum\limits_{i=1}^l\xi_i$$ Please explain to me in layman's terms what w (and ΞΎ) represent. Is w the distance to the ...
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8 views

Different Scoring with libsvm

I have been using libsvm for binary classification, e.g. given data $(x_1,\dots,x_n)$ and labels $(y_1,\dots,y_n)$ where $y_i\in\{0,1\}$. Now I am wondering if the prediction of my model can be tuned ...
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45 views

SVM cost parameter

In a SVM with linear kernel, could you explain to me what exactly the C parameter is/represents? An example why it's important to select a good value for C would also be appreciated. Thank you.
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36 views

Cross Validated Squared Correlation Coefficient in SVM regression

I am applying SVM regression on a data set on "Karthikeyan Melting Point Dataset" present here. I am using LIBSVM for it. After applying regression LIBSVM returns the cross validated squared ...
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36 views

Using LibSVM regression to predict dependent variable

My intention is to use SVR with 1-10 independent variables to best predict a dependent variable. After separating the data into scaled training and testing files containing the independent variables ...
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21 views

How to increase a particular terms's weightage?

I am doing Text classification using LibSVM in Rapid Miner. I am using TFIDF values for processing documents. I need to Increase weightage of some terms in the documents(for eg. words in BOLD and ...
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74 views

Extracting decision function variable from libsvm

I'm trying to use LIBSVM's single class SVMs for some classification and need to extract the following sum post classification (i.e. the variable that the decision function takes in) $$ ...
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32 views

One vs All appraoch to multiclassification in LIBSVM

I'm working on multiclass classification problem (precisely 4 classes). I want to use the most simple approach for this problem: one-vs-all! I have 4 different test set (only labels are different). ...
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173 views

Plotting the decision boundary of a kernel SVM (RBF)

Suppose we are given a training set of 2D points that are linearly non-separable. I train a binary SVM with an RBF kernel in order to classify them. What I want to do is to draw the desicion boundary. ...
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35 views

STRING KERNELS FOR LIBSVM

I'm working on a protein classification problem and i'm using edit distance kernel defined in libSVM. Now, for instance, the implementation of spectrum kernel is very difficult, but i want try to test ...
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32 views

Evolution strategies in libsvm

I'm working on protein multi-classification problem. I'm using libsvm and the edit distance kernel. This kernel depends from a parameter (gamma). I'm able to get the best parameters (gamma and C) ...
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27 views

Cross validation and accuracy calculation in lib-linear

I have two questions related to cross validation in LIBLINEAR I have 1000 documents from which i take 300 documents for training and rest 700 for classification . I train 300 documents with ...
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38 views

Different results in libsvm and R for regression prediction

i use e1071 package in R for SVM regression prediction and tried the same test in C# libsvm and got different results. All the parameters (gamma,cost,eps) are the same and so is the scaling method. ...
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46 views

LIBSVM RBF kernel time complexity

Is it known what is the LIBSVM time complexity when using RBF kernel functions?
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23 views

LIBSVM not Perfoming well in weka as opposed to other algorithms

I do have an issue with libSvm Weka which i feel it is very weird However, when i tried it with other algorithms such as naive bayes and j48, it achieved a high accuracy of 78%. Moreover, the same ...
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47 views

LIBSVM evaluation functions for probability estimation

I found this tool that is providing some well known evaluation functions like precision and recall. Unfortunately this tool supports only binary-class C-SVM. I was wondering where I can find similar ...
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12 views

libSVM can do external validation?

There is an option for libSVM do an external validation (external data) like for cross validation (-v mode) ? Thanks. Andre
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52 views

Training a multiclass SVM

I am using Support Vecotr Machine(SVM) with 4 Class. My corpus contain 185 documents with 4 different subjects. For each subject I defined a profile with 3 or 4 keywords (of course they are separated ...
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37 views

All positive labels when libsvm classifier is used in MATLAB

I have written a binary classification in MATLAB, using libsvm. The code is the following: ...
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91 views

Set up a classification experiment via libsvm (MATLAB)

I would like to set up an experiment in MATLAB, to predict the class of a set of text instances in a two-class problem (e.g., the text talks/does not talk about ...
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157 views

Choosing correct C and g parameters for libsvm

libsvm 3.18 Features: 10 I have used following, parameter range: ...
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84 views

LIBSVM overfitting

I trained two svms (LIBSVM) with 15451 samples after I did a 10-fold cross-validation and found the best parameter values for gamma and C (RBF kernel). In one svm I used just 1 feature and in the ...
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99 views

One class classifier Cross validation

I am working on a problem which requires one-class classifier. I am using LIBSVM. I know there are tons of material out there but still I could not find the answer to my query. How do I estimate the ...
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107 views

How to analyze plot from libsvm grid-search

I am trying to learn to use libsvm, I have used some defalut training sets to generate the plots by grid-search and obtained a plot below. I want to know, What type of plot is this, What does it ...
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33 views

Effect of high number of support vectors

I am doing Rainfall-Runoff modeling. I have 4014 inputs and 4014 outputs. I am confused about the of support vectors. Suppose I have a model having 2000 support vectors and I have another model having ...
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80 views

Accuracy changes with permutation of input data in Libsvm with precomputed kernel?

I'm doing quite simple SVM classification at the moment. I use a precomputed kernel in LibSVM with RBF and DTW. When I compute the similarity (kernel-) matrix, everything seems to work very fine ... ...
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15 views

Support Vector Machines…||w||, support vector coefficients, etc

I'm working with LibSVM and Matlab but am running into some issues. Specifically, I think I'm misunderstanding some theory. I've read here and there about the support vector coefficients, but I ...
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98 views

LIBSVM cross-validation - number of folds vs. sample size

I am using LIBSVM for classification and the default RBF Kernel. To get optimal parameters for C and gamma, I am using the grid.py tool included in the LIBSVM package. It is based on a k-fold ...
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46 views

SVM classifier - grid search on C and gamma no affect

I'm working to find the best C and gamma values for the RBF on my dataset using an SVM classifier. Specifically, I'm using LibSVM & MATLAB. ...
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159 views

Matlab - nu-support vector regression with LibSVM

I've 2 problems when applying $\nu$-SVR with LibSVM in Matlab. How to extract support vector from training model in $\nu$-SVR? When I visualize slab tube for a ...
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56 views

Which machine learning method to use for geographic systems prediction?

I am trying to do experiments on geographic systems prediction. We're working on classifying the location where we sell product most. So, we need to analyze the hestorical data and predict the success ...
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1answer
35 views

How do interpret statistically NULL SVM Output

I am using LibSVM (3.18) as an implementation of SVM. But every time when I'm predicting the result, it's giving zero. I am following these instructions: I have CSV file (+50K lines), Most of data ...
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3answers
146 views

SVM for unbalanced data

I want to attempt to use Support Vector Machines (SVMs) on my dataset. Before I attempt the problem though, I was warned that SVMs dont perform well on extremely unbalanced data. In my case, I can ...
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116 views

libsvm grid search on Parallel Computing Toolbox Matlab

I am using the following code for grid search on libsvm: ...