Takes a bunch of sequence files that are in the mahout classification format (groupId/unique-id) and creates another bunch of sequence files with each file having items from only 1 group id
This code will primarily be used by the classification utilities in mahout. After doing a seq2sparse, we get the vectors in a sequence file format. However, the keys in these sequence files are random i.e the special meaning that mahout assigns the keys i.e (category-id/unique-item-id) is not considered.
We would like to use the --testSplitPct option of the mahout split utility to split the data into training and test data
But the problem is that to use this option, the input directory needs to have 1 sequence file per category.
So, in this code we're simply going to pass through all the sequence files in the input directory and create output sequence files that have only 1 group in them