How to create a class with an attribute that provides its own __getitem__() method.

indexer_attrib_demo.py

#!/usr/bin/env python

"""
How to create a class with an attribute that provides its own __getitem__()
method (similar to pandas.DataFrame.ix).
"""

class Indexer(object):
    def __init__(self, data):
        if not hasattr(data, '__getitem__') or not hasattr(data, '__setitem__'):
            raise ValueError('cannot create indexer for specified data')
        self._data = data

    def __getitem__(self, x):
        return self._data[x]

    def __setitem__(self, k, v):
        self._data[k] = v

class DataClass(object):
    def __init__(self, data):
        self._data = data
        self._ix = Indexer(self._data)

    @property
    def ix(self):
        return self._ix

if __name__ == '__main__':
    import numpy as np
    d = DataClass(np.random.rand(10))
    print d.ix[0:5]
    d.ix[0:5] = 1
    print d.ix[0:5]