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Asked: 2026-05-22T22:42:58+00:00

I’d like to write a spam filter program with SVM and I choose libsvm

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I’d like to write a spam filter program with SVM and I choose libsvm as the tool.
I got 1000 good mails and 1000 spam mails, then I classify them into :
700 good_train mails 700 spam_train mails
300 good_test mails 300 spam_test mails
Then I wrote a program to count the time of each words occur in each file, got result like: 

good_train_1.txt:  
today 3  
hello 7  
help 5  
...

I learned that libsvm needs format like:

1 1:3 2:1 3:0
2 1:3 2:3 3:1
1 1:7 3:9

as its input. I know that 1, 2, 1 is the label, but what does 1:3 mean?
How could I transfer what I’ve got to this format?

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1 Answer

  1. Editorial Team

    Likely, the format is 

    classLabel attribute1:count1 ... attributeN:countN

    N is the total number of different words in your text corpus. You will have to check the documentation for the tool you are using(or its sources), to see if you can use a sparser format by not including the attributes having count 0.

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