Questions tagged [libsvm]
16
questions
1
vote
0
answers
11
views
How to normalize(or other) the audio data so that the same labels with the similar characteristics from different records?
I am trying to detect swallows from recordings taken from hospital. I manually labelled the recordings on the Praat. Now the valid labels are silence, swallows and nonswallows(noise, enviromenment ...
- 11
0
votes
0
answers
35
views
Sklearn SVM slower than when run in GridSearchCV
Problem:
Running SVM in GridSearchCV is faster than running without it and supplying only 1 value of C and no CV.
The AUC on the test set is lower when SVM is run outside of GridSearchCV.
Background:...
- 1
3
votes
1
answer
213
views
Implementing a weighted support vector machine in python
I have the following problem.
The minimization problem of the SVM that I want to solve is:
$$
\min_{w, b} \frac{1}{2}w^{T}w + \sum^{m}_{i=1}C_{i}xi_{i}
$$
Subject to:
$$
y_{i}(w^{T}x_{i} - b) \geq 1 - ...
- 33
3
votes
1
answer
2k
views
Convert Pandas Dataframe with mixed datatypes to LibSVM format
I have a pandas data frame with about Million rows and 3 columns. The columns are of 3 different datatypes. NumberOfFollowers is of a numerical datatype, UserName is of a categorical data type, ...
- 359
0
votes
1
answer
179
views
SVM SVC: Metric for parameter optimization on imbalanced data
I trained a multiclass SVC with RBF kernel on a down-sampled (and therefore balanced) dataset.
Now I want to perform grid search to find best cost and gamma.
What performance metric should I optimize ...
- 55
1
vote
0
answers
24
views
Practical examples/tutorials of using One-Class Support Vector Machines
I am a newbie in machine learning, and hope to solve an anomaly detection task using One-Class Support Vector Machines (OCSVM). ...
- 121
0
votes
1
answer
1k
views
Linear SVM in matlab and python giving different results
I have a particular dataset on which I am getting different results when using a linear SVM in matlab and sklearn toolbox.
The data has been normalized in matlab and imported into python from a mat ...
- 21
2
votes
1
answer
1k
views
Why Liblinear performs drastically better than libsvm linear kernel?
l have a dataset of dim=(200,2000) 200 examples and 2000 features. l have 10 classes.
l used sklearn for both cases :
svm.svc(kernel=linear)
LinearSVC()
...
- 225
4
votes
1
answer
6k
views
What is the difference between Linear SVM and SVM with linear kernel?
I'm wondering whether there is a difference between Linear SVM and SVM with a linear kernel. Or is a linear SVM just a SVM with a linear kernel?
If so, what is the difference between the two ...
- 225
-2
votes
1
answer
2k
views
Where can I find python code for SVM that use multiple feature data? [closed]
I am trying do an Image Classification where each sample of training data contains data of the current pixel with the 8 surrounding ones.
Where can I find examples of SVM, in python, that use 5 or ...
- 143
1
vote
0
answers
61
views
Obtain standard deviation for libsvm
I have the following code for Grid search, but it only return the accuracy result using 5 folds cross-validation. Is it possible to obtain standard deviation from the 5 folds CV. How would you do that?...
- 21
0
votes
2
answers
4k
views
Is standardization needed before using scikit-learn SVM?
I am using the SVM function provided by scikit-learn. I would like to know whether I need to perform standardization before fitting the model. As I know, LibSVM ...
- 243
1
vote
0
answers
92
views
$\chi^{2}$ kernel SVM performance issue
I am using $\chi^{2}$ kernel for non-linear SVM (using libSVM) for classifying MNIST digits. I am getting very bad performance (worse than random guessing). The $\chi^{2}$ kernel code (in MATLAB) is ...
- 3,695
1
vote
2
answers
259
views
Prepare data for SVM, Is it valid to normalise the data before and after PCA dimension reduction
Is it valid to normalise a dataset, reduce dimensionality with PCA and then to normalise the reduced dimension data. Assuming this is performed on training data, should the same PCA coefficients be ...
- 11
0
votes
2
answers
574
views
Understanding text conversion into SVM input [closed]
In Support Vector Machines, when used for sentiment analysis, text gets converted into a set of data points. How does this happen, usually?
17
votes
2
answers
432
views
Use liblinear on big data for semantic analysis
I use Libsvm to train data and predict classification on semantic analysis problem. But it has a performance issue on large-scale data, because semantic analysis concerns n-dimension problem.
Last ...
- 283