Sort python dictionary by Keys formatted as strings

Question

I have a dictionary with strings as keys formatted as yyyy-mm-dd and want to sort the dictionary by keys with the earliest dates first:

I am currently using sorted(datesAndText.keys()) but this isn't reliably working because the month and day fields are not always zero padded.

I have looked at Sort python dictionary by date keys and How do I sort this list in Python, if my date is in a String? but I can't seem to adopt them to by specific case.

Answer 1

Are you sure your keys are exactly in the format yyyy-mm-dd? For example:

>>> '2010-1-15' < '2010-02-15'
False

You may be forced to sort something like this:

sorted(d,key=lambda x: [int(y) for y in x.split('-')])

Another solution (assuming your years are all 4 digits):

sorted(d,key=lambda x: [y.zfill(2) for y in x.split('-')]) 

I'm not sure which would be faster. I suppose it's a candidate for timeit.

Answer 2

Dates in yyyy-mm-dd format sort the same way both alphabetically and chronologically, so you can use standard sorted:

for k, v in sorted(datesAndText.items()):
    # do something with key and value