On Oct 25, 2008, at 8:32 PM, pols cut wrote:
I am trying to write a map reduce function which takes take the
following types of <key,value> pairs
Map function -- should read floating point values (i dont really
care about key)
it should output <null,floatwritable>
If the input is stored in a text file, using TextInputFormat is right.
Your map inputs will be:
LongWritable, Text
Just use the Text and convert it to a Double.
reduce -- input- <null,floatwritable>
output <null,floatwritable>
This doesn't make any sense. How should the input to the reduce be
sorted? By the float? In that case, it would be:
FloatWritable, NullWritable
You will get one call to the reduce for each distinct float value the
maps generate. The reduce can iterate through the NullWritables to see
how many times that key was generated.
-- Owen
