Question

Possible Duplicate:
Python dictionary, keep keys/values in same order as declared

I’m going through some exercises on code academy when I noticed the dictionaries I was creating inside my python interpreter were coming back with unexpected results.

I’m using python2.7 and when I enter:

>>> dict_a = {'x':9, 'y':10, 'z':20}

And I call it:

>>> dict_a
{'y':10, 'x':9, 'z':20}

So I put in:

>>> dict_b = {'a':1, 'b':2, 'c':3}
>>> dict_b
{'a':1, 'c':3, 'b':2}

I’m thinking I’ve missed something basic here but, after doing some searching I don’t know what? If someone could help explain why this is happening, it would be very much appreciated.

Answer 1

Dictionaries are unsorted. The order they display in is due to internal logic, and won’t correspond to the order you define them in. However, since you don’t access a dictionary by order but by key, this rarely matters.