# Tagged Questions

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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### Support vector data description (SVDD) [on hold]

How can i explain the dual of the SVDD method?. what's the influence of linear term on the dual objective function?
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### Cross validation for obtaining maximum median SRC Vaue

My dataset is comprised of 5 types of image's sets along with their distortions scores (DMOS) .Let us call the types as Type1,...
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### What will be the input value (i.e. $x$ and $x′$) of RBF kernel for a given dataset or data matrix $x$?

If $x$ is a data matrix or dataset then What will be the input value (i.e. $x$ and $x'$) of RBF kernel $K_r(x,x')=\exp(-\frac{\|x-x'\|^2}{r})$ ? I can understand $x$ is same as dataset or data matrix ...
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### what is the libsvm data format definition [closed]

Essentially what is "libsvm format" ? please explain your Response Fully because I am a beginner at AI and working on a topic modelling project. thanks
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### How to justify the usage of “Radial Basis Function” as a kernel for SVM [duplicate]

I ran SVM with several kernels on my data. RBS has the best performing results. The task is similar to the text classification. I wonder how I can explain why RBS is actually the best kernel for my ...
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### TOO low estimated SVM probability for most of the negative test examples?

I am using LIBSVM (as well as the fitcsvm and fitSVMPosterior of ...
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### How to select weights in the F-Measure to be aligned with that used in cost-sensitive SVM training?

I am dealing with a classification problem in which Recall is more important than Precision, and the training dataset is an imbalanced one. The approach I am taking is to use oversampling to mitigate ...
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### Tweaking SVM error rates?

I currently have a one-vs-all SVM setup. Each SVM outputs a score. If I take the maximum score as the correct corresponding class, this gives me FARs of 0.008%. However it also gives me FRRs of about ...
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### Handling imbalanced datasets and misclassification costs in SVMs?

I have a dataset with 50 times more negative examples than positive ones. Currently, I am using an oversampling technique to address the imbalance problem. During the model selection stage (i.e. 5X5-...
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### Decreasing the number of negative examples with respect to the positive examples produces good prediction with SVM

Inroduction We have a binary classification problem and we want to learn a linear SVM (support vector machine). The dataset is composed of: 502 positive examples 5020 negative examples An example ...
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### Does LibSVM use Platt Scaling?

I have a binary SVM. I am wondering whether the percentage results that LibSVM gives for each class are Platt scaled?
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### Support vector regression (LIBSVM) returns out of range outputs when I use out-of-sample data to predict one step ahead (MATLAB)?

I'm using SVR model in MATLAB R2016a using this option: options_z = ['-q -s 3 -t 2 -c ', C_param, ' -p ', epsilon, ' -g ,Kernel_scale]; I'm optimizing SVR ...
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### What should this SVM's input look like?

I'm analyzing curves. Curves consist of a finite number of coordinates x and y. For any 3 two consecutive points of every curve i'm calculating AB angle (the angle between the line AB and the ...
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### One-vs-many/One-vs-all - what value to use as probability?

I have constructed SVMs to do a one-vs-many approach to classification. Let's say I have 3 classes and I train 3 SVMs in a one-vs-many format. This gives me 3 SVMs each trained positively on one of a ...
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### What is unbalanced data in libsvm?

My full data set (inclusive of both trng & test) has about 350 rows. They are of 3 classes (1,2,3), 1 has about 70, 2 has 125, 3 has 150. The above distribution across the labels is playing a ...
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### How to use Cross_validation output of svm-train?

I am getting very poor values with a certain data set I have. I tried to use the -v option of svm-train but later realized that this does not produce any model file for prediction. So what is the ...
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### What does the number 'Kernel Option' refer to in SVM?

I read that the performance of some kernel functions in SVM can change if we change the number known as kernel option. For example, this article states that kernel option of value 2 was used, http://...
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### How to use final svm regression model to predict new values of the dataset

I understand svm_predict function can be used to estimate or predict test output, but the arguments passed are like this svm_estimate = svmpredict(y, X, model); ...
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### Use cross-validation trained models for out-of-sample prediction or train a new model using whole data?

I'm using support vector regression(SVR) model and 5-fold cross validation for price prediction. which one is more appropriate after training models for out-of-...
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### Any methods to reduce the execution time taken by support vector regression libsvm algorithm?

I am currently working on dataset with 4 input dimensions and 1 output, in each approximately 7000 values hence overall 7000X5 dataset. I chose to use support vector regression and this takes a long ...
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### Performance metric for one-class SVM classifier with small number of instances

I am using LibSVM one-class classifier for detecting a particular hand gesture from accelerometer data. I have trained two categories of classifiers: (a) user-dependent: data from the same user is ...
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### AUROC for SVM two class classification [duplicate]

I'm trying to compute the ROC and AUROC of a binary svm classification. I already looked up a code in the internet and it's working: ...
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### Interpretation of SVM accuracy

I use "LIBSVM" library for classification. If my first class is the same as the second class, for accuracy I will get 50% or 0%. What does it mean to get 30% or 20% of precision?
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### Should the target variable be also normalised in SVM?

I understand that normalization is an important preprocessing step for using SVMs, esp. before using non-linear kernels such as the radial basis functions. Should this normalization be applied to the ...
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### Machine Learning SVM

If one trains a model using a SVM from kernel data, the resultant trained model contains support vectors. Now consider the case of training a new model using the old data already present plus a small ...
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### SKLearn SVC predicting perfectly with random features

I am using an SVC to do binary classification. I am using the rbf kernel and doing leave-one-out cross validation to choose my value of C. I ran the model using my normal features and had a detection ...
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### Does the confidence measure of a SVM have a meaning that can be compared across different models?

Suppose I train two SVMs ($m_1$ and $m_2$) on two different (potentially unrelated) problems. I then present datum $d_1$ to model $m_1$ and it outputs a vector $v_1$ of probabilities over the space ...
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### How to boost the performance of support vector machine?

I have 4 different data samples: Stage 1: [152 X 27578] Stage 2: [48 X 27578] Stage 3: [48 X 27578] Cancer: [63 X 27578] Each sample are the different stage of cancer in descending order. Here I ...
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### Boosting the prediction results in machine learning

I am having the datasets of 152 samples and 151 features.I implemented libSVM algorithm as a classifier. I am getting a classification accuracy just above 55% Is there any way I can boost my results....
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### linear kernel SVM

The linear kernel is defined as: $K(x1,x2)=\langle x1,x2\rangle$. I can see that all that this kernel does is to calculate the dot product in the original space of the data. Why is this kernel then ...
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### epsilon svr - How to control number of support vector?

I used epsilon SVR in libsvm for predicting time series data, which has approximately 117 rows I used 4 data (t-4, t-3, t-2, t-1) to predict the next data(t). I used gaussian RBF as kernel function. ...
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### Is it acceptable to use class probabilities as weights for a weighted average when the bins are numbers 1 to 5?

I have a Multi Class SVM that can predict what class some observation belongs to. There are 5 classes. They are trained for observation that scored 1 to 5. I want the MC-SVM to predict a class for ...
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### SVM accuracy after log transformation

I am using SVM (RBF kernel, the LibSVM implementation) to deal with a classification problem. When I use a log 10 transformation for may features values instead of using the default scaling method ...
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### Is validation set important in SVM regression analysis

I am new to machine learning and currently reading a paper about a ANN modelling in which they have divided their dataset into Training , validation and testing set. I have carried out some minor SVM ...
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### Over sampling imbalance data in SVM

Basically I have a medium size data set (20,000 observations) with only 200 being in group 1, thus an imbalanced data set. My goal is to predict as much group 1 class as possible without sacrificing ...
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### High difference between cv rate and classification accuracy in libsvm

edit: nevermind I solved it I am training an svm on a dataset with 5 classes using libsvm. I have a training set and a test set. I am using the easy.py script. The accuracy is a lot worse than the ...
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### How probabilities are calculated for SVM model?

I would like to know, how probabilities are calculated in support vector machine. I have used Iris data set and here is my decision values for three "SupportVectorMachine" (please find the PMML below ...
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### How to use svm-scale in LIBSVM?

I tried svm-scale -l 0 -u 1 -s range data.data > data_scaled.data but got error: I run the command in windows DOS command box. And I use python interface. Is my ...
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### How to extract descriptor values correctly from positive images with HOG? OpenCV

I have extracted descriptor values from positive and negative training set. For positive images, I have cropped objects (bicycle) from positive images, and only extracted descriptor values from them, ...
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### Proper scaling of training and test files

I'm trying to classify the web traffic according to the variation of the delay; my goal is to distinguish streaming traffic from downloading traffic. So far, my classes are: ...
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### What is the structure of the testing data file in libsvm? [closed]

According to the README file: The format of training and testing data file is: label index1:value1 index2:value2... My training file would be something like this: ...
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### libsvm to liblinear migration

I've reached the point when svmlib works too long so I decided to switch to liblinear instead. My question is how to properly transfer parameter training from libsvm to liblinear Say, if I have the ...
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### LibSVM parameter tuning

I am working on LibSVM to classify user comments as negative and positive. I am trying all possible parameter right now however i was not able to find useful information about these parameters Can ...
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### How to input data in libsvm for time series prediction using support vector regression?

I am using libsvm to perform time series prediction using support vector regression. Say my series is [11,22,33,44,55,66,77,88,99] and I decide the value of optimum lag to be 2.So from 11 and 22, I ...
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### Low cross validation accuracy in L1 Logistic Regression

My question is about the use of L1 Logistic Regression for discriminant analysis (feature selection) in extremely large datasets. I am using liblinear https://www.csie.ntu.edu.tw/~cjlin/liblinear/ for ...
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### SVM feature reduction

Suppose task where you need to classify texts using SVM. So before that you need to extract some features from texts. Suppose you pick up many of them and get huge vector. Is there any automatic ...
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### libsvm probability seems inverted

I started using libsvm a few days ago. Previously I used OpenCV implementation of SVM, but I needed probabilities on estimation and a read that with libsvm is possible. I started with a simple example ...
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### Usage of -b in svm-predict in libsvm

I have to use libsvm for scene-recognition. I have just started reading its usage here in github. I wanted to know what does '-b' exactly does in following usages svm-train -s 0 -b 1 data_file svm-...