title: Mahout Item Similarity Output Empty
body: <p>I'm using Mahout's ItemSimilarityJob to compute similarity of items with an input .csv file that looks like this:</p>
  
  <p><code>user_id(numbers only), song_id(numbers only), listens(numbers only)</code></p>
  
  <p>When I run the ItemSimilarityJob with these parameters</p>
  
  <p><code>$MAHOUT_HOME/bin/mahout org.apache.mahout.cf.taste.hadoop.similarity.item.ItemSimilarityJob --input inputcsv/ --output outputcsv --similarityClassname SIMILARITY_PEARSON_CORRELATION --tempDir tempcsv --booleanData true</code></p>
  
  <p>I get a blank part-r-00000 file inside music/csvoutput directory. There are many files inside music/csvtemp however. What could be the reason?</p>