Time for action – summarizing the shape data

Just as we provided a summarization for the overall UFO data set earlier, let's now do a more focused summarization on the data provided for UFO shapes:

1. Save the following to shapemapper.rb:

   #!/usr/bin/env ruby
   
   while line = gets  
       parts = line.split("\t")    
       if parts.size == 6        
           shape = parts[3].strip     
           puts shape+"\t1" if !shape.empty?   
       end     
   end     

2. Make the file executable:

   $ chmod +x shapemapper.rb
   

3. Execute the job once again using the WordCount reducer:

   $ hadoop jar hadoop/contrib/streaming/hadoop-streaming-1.0.3.jarr --file shapemapper.rb -mapper shapemapper.rb -file wcreducer.rb -reducer wcreducer.rb -input ufo.tsv -output shapes
   

4. Retrieve the shape info:

   $ hadoop fs -cat shapes/part-00000  
   

What just happened?

Our mapper here is pretty simple. It breaks each record into its constituent fields, discards any without exactly six fields, and gives a counter as the output for any non-empty shape value...