Get last value of an OrderedDict in Python3

Question

Here is way to get the last key of an OrderedDict in Python3.

I need to get last value of an OrderedDict in Python3 without conversions to list.

Python 3.4.0 (default, Apr 11 2014, 13:05:11) 

>>> from collections import OrderedDict
>>> dd = OrderedDict(a=1, b=2)
>>> next(reversed(dd))
'b'

>>> next(reversed(dd.keys()))
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: argument to reversed() must be a sequence

>>> next(reversed(dd.items()))
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: argument to reversed() must be a sequence

>>> next(reversed(dd.values()))
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: argument to reversed() must be a sequence

Oops, looks like I overlooked the obvious solution: `dd[next(reversed(dd))]` — warvariuc, Sep 01 '14 at 07:58

score 7 · Accepted Answer · answered Sep 01 '14 at 08:13

7

Just use that key to index the dictionary:

dd[next(reversed(dd))]

For example:

from collections import OrderedDict
dd = OrderedDict(a=1, b=2)
print(dd[next(reversed(dd))])     # 2

answered Sep 01 '14 at 08:13

enrico.bacis

30,497
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score 2 · Answer 2 · answered Dec 11 '20 at 08:41

2

This was fixed in Python 3.8 (https://bugs.python.org/issue33462).

>>> from collections import OrderedDict
>>> dd = OrderedDict(a=1, b=2)
>>> next(reversed(dd.keys()))
'b'
>>> next(reversed(dd.values()))
2
>>> next(reversed(dd.items()))
('b', 2)

answered Dec 11 '20 at 08:41

warvariuc

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Get last value of an OrderedDict in Python3

2 Answers2