Matlab Weka Interface Java Exception

Hi,

Not sure if this is where I should post this question, since it is on something I downloaded from the FileExchange. If that's the case, please let me know where I should put this.

I'm trying to use the matlab weka interface that I downloaded from here: http://www.mathworks.com/matlabcentral/fileexchange/21204-matlab-weka-interface

Here is my code:

classifier = trainWekaClassifier(matlab2weka('comp', featurelabels, feature, w), 'functions.Logistic', {'-R 100'});

featurelabels is a 1x211 cell array containing strings naming my features. Ex: 'C1V1'

feature is a 172x211 cell array containing feature values in the first 210 columns, and then labels in the 211th, which are either 'C' or 'N'. w is 211.

It is throwing the following error:

??? Java exception occurred:
java.lang.ClassCastException: java.lang.Character cannot be cast to java.lang.String

  at weka.core.Attribute.<init>(Attribute.java:339)

  at weka.core.Attribute.<init>(Attribute.java:298)

Error in ==> matlab2weka at 37
                vec.addElement(Attribute(featureNames{i},values));

Error in ==> wekacomptrain at 33
classifier = trainWekaClassifier(matlab2weka('comp', featurelabels, feature, w),
'functions.Logistic', {'-R 100'});

I'm not sure what I'm doing incorrectly - any help would be appreciated. Thanks!

Answer 1

[Nicole]

Ok actually I've figured it out, and I think it's worth putting the answer here because it is a little bizarre. If you don't add double quotes ("") around your matlab strings, you will get this error. So, by changing my feature names from things like 'C1V1' in Matlab to '"C1V1"' I was able to solve the problem.

Answer 2

[parmin]

Hi, I have a problem like you. but I can not understand your answer! can you explain more than it? what is your mean of this sentences : "by changing my feature names from things like 'C1V1' in Matlab to '"C1V1"' I was able to solve the problem. "

your featurename is like age or name column in dataset or it is contents of age or name?

I think problem is for values in this lines: vec.addElement(Attribute(featureNames{i},values));

I'm waiting for your answers. thanks

Answer 3

[parmin]

I understand why this error appear. when I want to send a single character such as f/m for attribute sex this errors caused. but for more than 1 character such as male or no there is no problem! if I put the characters in "" such as you have done, it is would be like this in arff format ' " \ y \ " '.so this state would not be work in weka!

would you mind help me to solve this problem?

[Nicole]

Hi, I am not sure I understand your question. I used .csv files as input to weka. Each column of the csv file corresponds to a feature, such as sex, age, or name, to be used in the classification. The first row of the .csv file contains the names of the features. The rest of the rows contain their values. What you are having a problem with is that your values are not numbers, but strings (f/m). I don't know if Weka supports that. Try making them numbers (1 for female, 0 for male) and see if that fixes the problem.

[parmin]

Hi, I can change (f/m) to numbers but I want to use the form of strings not numbers!for example some of my values are like this: @attribute cap-shape {b,c,f,k,s,x} so change them to numbers is not good for me!

[parmin]

Do you understand my request or My request is not executable in matlab?