Pig 0.12 introduced streaming python UDFs, but they're experimental, so they need Hadoop 1.
http://pig.apache.org/docs/r0.12.1/udf.html#python-udfs
However, the only Amazon-provided AMI that can use pig 0.12 is AMI 3.1.0, which uses hadoop 2.4, not Hadoop 1:
http://docs.aws.amazon.com/ElasticMapReduce/latest/DeveloperGuide/emr-plan-hadoop-version.html
So, the only AMI that supports the right version of pig doesn't support the right version of hadoop. Is there a way to get streaming UDFs working on EMR?