Code Style and Conventions

Python 2/3 Compatibility

Before #4384, pandas depended on the 2to3 tool to ensure that the codebase was Python 2 and 3 compatible. This is not the case anymore. That means that you should be careful about writing code that is Python 2 and Python 3 compatible. To that end, there are new internal functions that abstract away the details of the API changes between the two major versions of Python along with the six module now shipped with pandas.

In particular, there are the functions lrange, lzip, lmap, lreduce, and lfilter which all return lists no matter what version of Python is used. These functions live in the pandas.util.compat module.

These are the equivalent of wrapping each of range, zip, map, reduce, or filter in a call to the list constructor, e.g. list(zip(...)). It is advised to use these functions when you know you need a list object and to use the others when you need to iterate over the resulting object.