I am working on sentiment analysis of tweets. I am using mahout naive bayes classifier for it.I am making a directory "data".Inside "data" I am making three more directories named "positive","negative","uncertain"..Then I kept 151 files(total 151Mb) on each of these positive,negatie and uncertain directory..Then I kept the data directory in hdfs..below are the set of command i ran to generate the model and labelindex out of it.
bin/mahout seqdirectory -i ${WORK_DIR}/data -o ${WORK_DIR}/data-seq
bin/mahout seq2sparse -i ${WORK_DIR}/data-seq -o ${WORK_DIR}/data-vectors -lnorm -nv -wttfidf
bin/mahout split -i ${WORK_DIR}/data-vectors/tfidf-vectors --trainingOutput ${WORK_DIR}/data-train-vectors --testOutput ${WORK_DIR}/data-test-vectors --randomSelectionPct 40 --overwrite --sequenceFiles -xm sequential
bin/mahout trainnb -i ${WORK_DIR}/data-train-vectors -el -o ${WORK_DIR}/model -li ${WORK_DIR}/labelindex -ow $c
I am getting the confusion matrix after testing on the same set of data using "testnb" command as given below:
bin/mahout testnb -i ${WORK_DIR}/data-train-vectors -m ${WORK_DIR}/model -l ${WORK_DIR}/labelindex -ow -o ${WORK_DIR}/data-testing $c
Confusion Matrix
-------------------------------------------------------
a b c <--Classified as
151 0 0 | 151 a = negative
0 151 0 | 151 b = positive
0 0 151 | 151 c = uncertain
Then I created a some another directory "data2" in the same way and put some random data(which is a sub set of the training data(30 files(total size 30MB) each)) in positive,negative,uncertain directory inside it .Then i created a vector out of it using the "seq2sparse" command given below :-
bin/mahout seqdirectory -i ${WORK_DIR}/data2 -o ${WORK_DIR}/data2-seq
bin/mahout seq2sparse -i ${WORK_DIR}/data2-seq -o ${WORK_DIR}/data2-vectors -lnorm -nv -wttfidf
On running the "testnb" using the model/lablelindex created from the previous set of data using the command given below:-
bin/mahout testnb -i ${WORK_DIR}/data2-vectors/tfidf-vectors/part-r-00000 -m ${WORK_DIR}/model -l ${WORK_DIR}/labelindex -ow -o ${WORK_DIR}/data2-testing $c
I am getting confusion matrix like this.
Confusion Matrix
-------------------------------------------------------
a b c <--Classified as
0 30 0 | 30 a = negative
0 30 0 | 30 b = positive
0 30 0 | 30 c = uncertain
Can anyone tell me why this is coming.Am i using the correct way to test the model or it is a bug in mahout 0.7.If it is not the correct way please suggest a way out of it.
