How to reverse order of keys in python dict?

python dictionary reverse
zjm1126 picture zjm1126 · Mar 28, 2011 · Viewed 83.1k times · Source

This is my code :

a = {0:'000000',1:'11111',3:'333333',4:'444444'}

for i in a:
    print i

it shows:

0
1
3
4

but I want it to show:

4
3
1
0

so, what can I do?

Answer

SingleNegationElimination picture SingleNegationElimination · Mar 28, 2011

The order keys are iterated in is arbitrary. It was only a coincidence that they were in sorted order.

>>> a = {0:'000000',1:'11111',3:'333333',4:'444444'}
>>> a.keys()
[0, 1, 3, 4]
>>> sorted(a.keys())
[0, 1, 3, 4]
>>> reversed(sorted(a.keys()))
<listreverseiterator object at 0x02B0DB70>
>>> list(reversed(sorted(a.keys())))
[4, 3, 1, 0]

Related questions

Reverse / invert a dictionary mapping

Given a dictionary like so: my_map = {'a': 1, 'b': 2} How can one invert this map to get: inv_map = {1: 'a', 2: 'b'}

Read More
Sort a list of tuples by second value, reverse=True and then by key, reverse=False

I need to sort a dictionary by first, values with reverse=True, and for repeating values, sort by keys, reverse=False So far, I have this dict = [('B', 3), ('A', 2), ('A', 1), ('I', 1), ('J', 1)] sorted(dict.items(), key=lambda x: (x[1],x[1]), …

Read More
Iterating over dictionaries using 'for' loops

I am a bit puzzled by the following code: d = {'x': 1, 'y': 2, 'z': 3} for key in d: print key, 'corresponds to', d[key] What I don't understand is the key portion. How does Python recognize that it needs only to …

Read More