Slicing a Python OrderedDict

Question

In my code I frequently need to take a subset range of keys+values from a Python OrderedDict (from collections package). Slicing doesn\'t work (throws Typ

Answer 1

In Python 2, you can slice the keys:

x.keys()[1:3]

and to support both Python 2 and Python 3, you'd convert to a list first:

list(k)[1:3]

The Python 2 OrderedDict.keys() implementation does exactly that.

In both cases you are given a list of keys in correct order. If creating a whole list first is an issue, you can use itertools.islice() and convert the iterable it produces to a list:

from itertools import islice

list(islice(x, 1, 3))

All of the above also can be applied to the items; use dict.viewitems() in Python 2 to get the same iteration behaviour as Python 3 dict.items() provides. You can pass the islice() object straight to another OrderedDict() in this case:

OrderedDict(islice(x.items(), 1, 3))  # x.viewitems() in Python 2