Get year from unknown date format using python

Question

So I am querying a server for specific data, and I need to extract the year, from the date field returned back, however the date field varies for example:

The obvious would be to extract the date into a array and fetch the max: (but there is a problem)

year = max(d.split('-'))

for some reason this gives out false positives as 22 seems to be max verses 2017, also if future calls to the server result in the date being stored as "2019/10/20" this will bring forth issues as well.

If it's at least known that the year will always be the first 4 characters: d[:4]. And the reason max doesn't work for you is because you're comparing strings, you need to turn them into ints first: max(map(int, d.split('-'))). — deceze
– deceze ♦, Commented May 9, 2020 at 9:52

Thomas · Accepted Answer · 2020-05-09 09:53:02Z

4

The problem is that, while 2017 > 22, '2017' < '22' because it's a string comparison. You could do this to resolve that:

year = max(map(int, d.split('-')))

But instead, if you don't mind being frowned upon by the Long Now Foundation, consider using a regular expression to extract any 4-digit number:

match = re.search(r'\b\d{4}\b', d)
if match:
    year = int(match.group(0))

answered May 9, 2020 at 9:53

Thomas

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1 Comment

Błotosmętek Over a year ago

Ah, the feared Y10K problem… ;-)))

RoadRunner · Accepted Answer · 2020-05-09 10:02:15Z

2

I would use the python-dateutil library to easily extract the year from a date string:

from dateutil.parser import parse

dates = ['2009', '2009-10-8', '2009-10']

for date in dates:
    print(parse(date).year)

Output:

2009
2009
2009

edited May 9, 2020 at 10:02

answered May 9, 2020 at 9:56

RoadRunner

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