Bug in CrossValidatedMahoutKNNRecommenderEvaluator

[abellogin]

As reported by @afcarvalho1991 in #123:

CrossValidatedMahoutKNNRecommenderEvaluator not working, see Log below.

----------------------------- LOG --------------------------------------

5 [main] INFO org.apache.mahout.cf.taste.impl.model.file.FileDataModel - Creating FileDataModel for file data/ml-100k/model/train_0.csv 52 [main] INFO org.apache.mahout.cf.taste.impl.model.file.FileDataModel

Reading file info... Exception in thread "main" java.lang.NumberFormatException: For input string: "" at java.lang.NumberFormatException.forInputString(NumberFormatException.java:65) at java.lang.Long.parseLong(Long.java:601) at java.lang.Long.parseLong(Long.java:631) at org.apache.mahout.cf.taste.impl.model.file.FileDataModel.readTimestampFromString(FileDataModel.java:632) at org.apache.mahout.cf.taste.impl.model.file.FileDataModel.addTimestamp(FileDataModel.java:595) at org.apache.mahout.cf.taste.impl.model.file.FileDataModel.processLine(FileDataModel.java:512) at org.apache.mahout.cf.taste.impl.model.file.FileDataModel.processFile(FileDataModel.java:340) at org.apache.mahout.cf.taste.impl.model.file.FileDataModel.buildModel(FileDataModel.java:236) at org.apache.mahout.cf.taste.impl.model.file.FileDataModel.reload(FileDataModel.java:208) at org.apache.mahout.cf.taste.impl.model.file.FileDataModel.(FileDataModel.java:194) at org.apache.mahout.cf.taste.impl.model.file.FileDataModel.(FileDataModel.java:149) at net.recommenders.rival.examples.movielens100k.CrossValidatedMahoutKNNRecommenderEvaluator.recommend(CrossValidatedMahoutKNNRecommenderEvaluator.java:160) at net.recommenders.rival.examples.movielens100k.CrossValidatedMahoutKNNRecommenderEvaluator.main(CrossValidatedMahoutKNNRecommenderEvaluator.java:93) ------------------------------- end-LOG --------------------------------