Questions tagged [libsvm]

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)

Filter by
Sorted by
Tagged with
0
votes
0answers
26 views

Why do distances to hyperplane increase with more training samples in a One-Class SVM?

I am using a One-Class SVM from for anomaly detection. I observe that the distance of classified samples increases roughly proportional with the number of training samples. This is true for inliers ...
0
votes
0answers
13 views

Why are 'Mean squared error' or 'Squared correlation coefficient' only calculated for Epsilon SVR and Nu SVR?

Why does libsvm only calculate 'Mean squared error' or 'Squared correlation coefficient' the for SVM types of Epsilon-SVR and nu-SVR? What is the reason these aren't appropriate for C-SVC or nu-SVC? ...
4
votes
0answers
56 views

Does distance from the decision boundary suggest higher confidence that the class prediction is correct using SVM?

Does further distance from the decision boundary threshold suggest higher confidence that the class prediction is correct when using SVM with probability estimates enabled? This is not a question ...
0
votes
0answers
22 views

When performing a svm hyper-parameter search for epsilon coef0 and degree which min max and increment values are suggested?

I am using libsvm, but I think this applies to any ML algorithm where these kernels are used. The default implementation of libsvm suggests values for the linear kernel or RBF kernel hyper-parameters ...
2
votes
1answer
27 views

Which algorithm is implemented in sklearn's SVM method?

I'd like to know which exact version of svm is implemented in slearn. The references section on sklearn's svm page cites libsvm package and a paper from 1999 which is about comparing classification ...
3
votes
0answers
51 views

SVM Scaling problem with One-Class SVM

I'm trying to mess around with a one-class SVM implementation I hacked together from ArduinoSVM. I'm using an RBF kernel and training the model with just "in" datapoints with sklearn. First, as is ...
2
votes
1answer
38 views

LibSVM - interpreting model output

I am using libSVM on a subset of the MNIST, and I am struggling to interpret the output. I have learned that rho is the bias term, and that sv_coef is the multiplier used to get to the weight term. ...
0
votes
1answer
202 views

What are the weights assigned to the features (coefficients in the primal problem) in SVR? [closed]

In case of linear kernel, how to interpret the weights in the formulations of nu-SVR? I am using nu-SVR to estimate the parameters in GARCH(1,1) model:$ \sigma_t^2 = \omega + \alpha y_{t-1}^2 + \...
0
votes
0answers
106 views

hinge loss functions in SVM

Hi as I am writing report regarding the topic SVM and I have to elaborate on the differences between SVC and linearSVC in Scikit Learn, I search online that the two algorithms differ in terms of hinge ...
1
vote
1answer
72 views

Recover $\rho$ of $\nu$-SVM from e1071 package in R

Given a dataset $\{(x_i,y_i)\}_{i=1}^n$, the primal problem for $\nu$-SVM is: \begin{align} &\min_{w,b,\xi,\rho} && \frac{1}{2}w^\top w-\nu\rho+\frac{1}{n}\sum_{i=1}^n\xi_i\\ &\text{...
1
vote
1answer
38 views

Why setting SVDD's C-parameter to $> 1$ does not affect the result?

Why setting $C>1$ does not affect the result (compared to $C=1$) according to: https://www.csie.ntu.edu.tw/~cjlin/libsvmtools/#libsvm_for_svdd_and_finding_the_smallest_sphere_containing_all_data ...
1
vote
0answers
80 views

Range of Search Space for the hyperparameters of Support Vector Regresssion (SVR)

I need to know "what should be the practical range of c, gamma and epsilon hyper-parameters during grid search optimization in SVR". The range of dependent variable lies between 1 to 300 with mean ...
1
vote
1answer
463 views

How to perform kFold cross validation in Libsvm's precomputed kernel in MATLAB?

I understand that Libsvm provides 'v 10' option for 10-fold cross-validation in...
0
votes
1answer
50 views

Formatting 3d data for LIBSVM

I am going to use LIBSVM for classification of data that uses a 'feature window'. Currently my data is in the form of a M x N x 3 matrix - M instances, N features and for each feature I'm considering ...
4
votes
0answers
74 views

soft SVM - degenerate case

According to "A Note on Support Vector Machine Degeneracy", Theorem 4, if the dual problem for soft-SVM has a solution with $\alpha_i \in \{0,C\}, \forall i$, then $w=0$ for the primal problem. In "...
0
votes
1answer
43 views

SVM decision non linear

As I understand, to perform a decision in a non linear case (using a kernel) I use the following: $f(x) = sgn(\sum_{i=1}^{n} y_{i} \alpha_{i} \boldsymbol{k}(x,x_{i})+b)$ Where i=1,..n are the ...
2
votes
2answers
7k views

What is the parameter sigma in svm?

What is the influence of the sigma or gamma parameter for the rbf kernel? if possible a graph for a better understanding Is epsilon also known as SIGMA?
3
votes
1answer
2k views

What is the parameter nu in oneClass svm?

According to this link, nu specifies the nu parameter for the one-class SVM model. The nu parameter is both a lower bound for the number of samples that are support vectors and an upper bound for the ...
0
votes
2answers
116 views

I have 20000 potential features but only 200 instances, how can I do feature selection for an SVM classifier?

I have 20,000 potential features, but only 200 instances, how can I do feature selection for an SVM classifier, especially LIBSVM? Is there any fast way to do it rather than brute force? Since, ...
2
votes
0answers
30 views

For model selection, using n-fold cross-validation, should performance be averaged over the folds or calculated based on all predictions?

In $n$-fold inner-cross-validation, for model selection, should performance be calculated $n$ times and then averaged, or should all predictions be made covering the whole training set, and then ...
0
votes
0answers
97 views

Why SVM classifier generates bad results with LDA in Classification of audio data?

I am using SVM classifier to classify my audio data (instrument strokes). I am using LDA as a feature reduction technique to reduce feature dimensions. After applying classifier the results I am ...
3
votes
1answer
4k views

What Are Shrinking Heuristics

I have been working on a project with LibSVM and have noticed there is an option to train the SVM model with "shrinking heuristics" which are used to speed up the classifier training. After doing ...
-1
votes
1answer
42 views

Prepare data for previously trained LibSVM classifier

I trained a LibSVM classifier, with scaled features in the interval $[-1;1]$ with this equation: $$x'=2\frac{x-\min x}{\max x - \min x}-1$$ I am happy with the trained model and its accuracy on the ...
0
votes
0answers
101 views

One-class svm with given true positive rate

Is it always possible to find a one-class SVM with given true positive rate (TPR)? I used 1-D grid search with cross-validation to find the width parameter of RBF kernel with .90 TPR. The closest ...
2
votes
2answers
2k views

(SVM) Difference between linear kernel and polynomial kernel of degree 1?

I am new to machine learning. Could anyone tell me the difference between linear kernel vs. polynomial kernel of degree 1 wrt SVM (if there is any difference)? The reason I asked, I am getting ...
1
vote
0answers
178 views

Augmenting feature vector with bias in SVM: effect on kernel matrix

It is easier to optimise a SVM without an offset term $b$ since we get rid of one of the linear constraints in the dual formulation. If an offset is still needed, it has been suggested that the ...
6
votes
0answers
224 views

Optimising dual SVM: why do some authors drop constraints?

In Hastie's Elements of Statistical Learning the dual problem is put as $$ \begin{align} \text{arg min}_\alpha \quad &\ \frac{1}{2}\alpha^\top Q\, \alpha_i- \sum_i \alpha_i\\ \text{subject to}\...
3
votes
1answer
195 views

Most widely accepted method of SVM model validation?

I am building an SVM based classifier (libsvm) for two distinct balanced classes which are non-linear but separable with an RBF kernel. Both classes have 175 instances each, which must be utilized ...
0
votes
1answer
440 views

what's the more common name of “Three-way data splits”?

I'm using Libsvm to train the model but the result is always not so good. now I'm reading this lecture's document: http://research.cs.tamu.edu/prism/lectures/iss/iss_l13.pdf the lecture mentioned "...
-1
votes
1answer
708 views

How to use svm for a large dataset to predict

I am using svm method for prediction of wind power using windspeed. I have a large historical dataset containing timestamp, wind speed and wind power of size 6.74MB. it is a one year data at each 5 ...
0
votes
1answer
750 views

How to apply SVM model to new data using libsvm in MATLAB?

Suppose that I have trained and tested an SVM classifier with the following code: ...
4
votes
2answers
7k views

Can someone explain the RBF Kernel to me?

I have read every explanation out there on this but nobody seems capable of explaining this in a way that I am able to understand. For an SVM RBF Kernel we often say that: But what does x and x' ...
0
votes
1answer
67 views

Why is MSE difference between LIBSVM and my codes?

Now I used LIBSVM toolbox to solve a regression problem. However, I found a question that the value of MSE calculated by the toolbox was different with the value of MSE calculated by myself. Did you ...
1
vote
1answer
115 views

bias in SVM in a balanced set - effect of sample size?

I have a dataset with many subjects, and for each subject I have 100 samples for an X variable, while Y has exactly 50%/50% cases for label 1/2. I am trying to run cross-validation with SVM and found ...
0
votes
1answer
120 views

Does LibSVM output a broken SVM in epsilon-svr mode?

I run epsilon-svr on about 1000 samples (RBF kernel), and then calculate the in-sample training errors. The hyperparameters are found via a search, ranging from 1e-5 to 1e2. model->eps is a couple ...
1
vote
1answer
550 views

Svm-scaling for training and testing using libsvm on matlab [closed]

I want to use SVM-scale for both training and testing on Matlab using libsvm. In libsvm document implement this but using Python and I need for Matlab. how can I do it?
0
votes
1answer
647 views

Why all “nBSV”s are zero in LIBSVM classification outputs?

I'm training a classification SVM for a binary classification model with 20 features (LIBSVM). These are some reports of my model (with different combination of features). Why all ...
0
votes
1answer
139 views

Do input features need to be in a distribution?

I am currently starting my machine learning project on binary classification and I have been taught that input data features should be in a distribution (although the distribution type itself need not ...
-1
votes
1answer
93 views

Odd Behavior in Cutoff of Soft Margin SVM

In soft margin svm, we solve the following quadratic programming problem. $$ \text{maximize}\ \sum_{i=1}^N \alpha_i-\sum_{i=1}^N\sum_{j=1}^N\alpha_i\alpha_jy_iy_jX_i^tX_j,\\ \text{subject to}\ \sum_{i=...
1
vote
0answers
790 views

Standardizing vs Normalizing data for Support Vector Machines

I am fairly new to the topic of Support Vector Machines, and despite my readings, I still encounter difficulties in understanding the following: why do some people address the need to normalize data ...
1
vote
0answers
136 views

Below chance classification after regressing out class-specific signal

I have a signal X that depends on parameters Y (condition) and S (participant). I'm interested in classifying Y based on X, but a) the YxS contingency table of numbers of observations per Y and S ...
1
vote
0answers
177 views

Am I correct for cross-validation or validation set in libSVM?

I used libSVM in MATLAB to find whether there is some relationship between the features and label. My steps are: Divide the dataset in 60% for training, 20% for testing and 20% for validation. I used ...
2
votes
2answers
1k views

Do SVM suffer from imbalanced class sizes?

Say I have a population with classes c1 and c2 where size(c1) >> size(c2) Does the SVM suffer from imbalanced classes sizes where I need to manually correct the training procedure?
1
vote
0answers
267 views

How to use Probability (-b1) for one-class classification using LibSVM?

I need some information concerning the LibSVM one-class classification. I use -b1 for two-class classification in SvmTrain and my outputs are prob values and prob labels. I want to use the similar ...
0
votes
1answer
917 views

How to train an SVR model? [closed]

I'm trying to figure out how SVR works, as I need to use it to model some time series. For this purpose, before starting with this model, I've tried to create a toy-model from a sinusoidal function, ...
1
vote
1answer
613 views

Training a Support Vector Machine classifier on a satellite image using python

I am new to the concept of supervised classification technique. I am trying to use an SVM classifier for classifying Sea Ice types in the Arctic using satellite image. All the tutorials I have read ...
0
votes
1answer
219 views

One-to-rest Weight vectors in one-to-one multiclass SVC

I'm attempting to generate some one-to-rest weight vectors for a multi-class SVC for feature selection purposes. However, I'm current using one of the several LibSVM ports, which inherently performs ...
-1
votes
1answer
173 views

Using LibSVM for One-Class-Classification

Why do the same instances, in training and testing, get classified as unknown in LibSVM? I'm using the linear kernel function nu=0.1, gamma=0.1 Here is the instance that is in both the training and ...
4
votes
1answer
6k views

SVM: Why does the number of support vectors decrease when C is increased?

I am learning how to use libsvm through sklearn.svm in python. I read here about what happens and why when you change the C value as part of your model. My intuition from what I've learned would be ...
1
vote
0answers
229 views

Using SVM regression model without cross-validation and parameter optimization

I am working on a regression model of quite complicated dataset. Dataset is heterogenous in the sense that it contains elements of significantly different properties. I am using $\epsilon$ type ...

1
2 3 4 5