Python: get all months in range?

Question

I want to get all months between now and August 2010, as a list formatted like this:

[\'2010-08-01\', \'2010-09-01\', .... , \'2016-02-01\']

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Answer 1

I don't know whether it's better, but an approach like the following might be considered more 'pythonic':

months = [
    '{}-{:0>2}-01'.format(year, month)
        for year in xrange(2010, 2016 + 1)
        for month in xrange(1, 12 + 1)
        if not (year <= 2010 and month < 8 or year >= 2016 and month > 2)
]

The main differences here are:

• As we want the iteration(s) to produce a list, use a list comprehension instead of aggregating list elements in a for loop.
• Instead of explicitly making a distinction between numbers below 10 and numbers 10 and above, use the capabilities of the format specification mini-language for the .format() method of str to specify
  • a field width (the 2 in the {:0>2} place holder)
  • right-alignment within the field (the > in the {:0>2} place holder)
  • zero-padding (the 0 in the {:0>2} place holder)
• xrange instead of range returns a generator instead of a list, so that the iteration values can be produced as they're being consumed and don't have to be held in memory. (Doesn't matter for ranges this small, but it's a good idea to get used to this in Python 2.) Note: In Python 3, there is no xrange and the range function already returns a generator instead of a list.
• Make the + 1 for the upper bounds explicit. This makes it easier for human readers of the code to recognize that we want to specify an inclusive bound to a method (range or xrange) that treats the upper bound as exclusive. Otherwise, they might wonder what's the deal with the number 13.