How to determine appropriate strftime format from a date string?

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The dateutil parser does a great job of correctly guessing the date and time from a wide variety of sources.

We are processing files in which each file uses only one date/time format, but the format varies between files. Profiling shows a lot of time being used by dateutil.parser.parse. Since it only needs to be determined once per file, implementing something that isn't guessing the format each time could speed things up.

I don't actually know the formats in advance and I'll still need to infer the format. Something like:

from MysteryPackage import date_string_to_format_string
import datetime

# e.g. mystring = '1 Jan 2016'
myformat = None

...

# somewhere in a loop reading from a file or connection:
if myformat is None:
    myformat = date_string_to_format_string(mystring)

# do the usual checks to see if that worked, then:
mydatetime = datetime.strptime(mystring, myformat)

Is there such a function?

datetime python
4 Answers

You can try dateinfer module. It's pretty nice and deals with all your cases easily. Though if you need more fine control over the code and are ready to write it from scratch, regex does look like the best option.

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