Question

in python, both the dict {1:1,2:2,3:3} and {3:3,2:2,1:1} produces "{1:1,2:2,3:3}" when str()’d?

Can I rely on this sorting, or at least on the fact that dicts containing the same key/valuepairs will generate the same string when put through the str() function?

Answer 1

You can rely on neither of these two properties. The order of a dictionary when converted to a string depends also on the insertion order of the key/value pairs.

With a bit of knowledge of the Python source code (watch The Mighty Dictionary from PyCon 2010), or a bit of trial and error, you can easily find counter examples:

>>> {1: 1, 9: 9}
{1: 1, 9: 9}
>>> {9: 9, 1: 1}
{9: 9, 1: 1}