Maybe it is the same has Hadoop but I just couldn't find what is the format or example of writing the map and reduce python code beside map example here: http://docs.amazonwebservices.com/ElasticMapReduce/latest/GettingStartedGuide/
but I couldn't find reduce code example,
is it the same as Hadoop? and what is the format and are there any examples anywhere?
EMR streaming is no different to general Hadoop streaming.
Here's an example of a python reducer http://www.michael-noll.com/tutorials/writing-an-hadoop-mapreduce-program-in-python/#reduce-reducer-py