python - datetime strptime - set format to ignore trailing part of string

Question

I have a string with variable length and I want to give a format to strptime in order for the rest of the string to be ignored. Let me exemplify. I have something like

9/4/2013,00:00:00,7.8,7.4,9.53
10/4/2013,00:00:00,8.64,7.4,9.53

and I want a format that makes the command strptime(line,format) work to read those lines. Something like format='%d/%m/%Y,%H:%M:%S*', although I know that doesn't work. I guess my question is kind of similar to this one, but no answer there could help me and my problem is a little worse because the full length of my string can vary. I have a feeling that dateutil could solve my problem, but I can't find something there that does the trick.

I can probably do something like strptime(''.join(line.split(',')[:2]),format), but I wouldn't want to resort to that for user-related issues.

Answer 1

You cannot have datetime.strptime() ignore part of the input.; your only option really is to split off the extra text first.

So yes, you do have to split and rejoin your string:

format = '%d/%m/%Y,%H:%M:%S'
datetime.strptime(','.join(line.split(',', 2)[:2]), format)

or find some other means to extract the information. You could use a regular expression, for example:

datetime_pattern = re.compile(r'(d{1,2}/d{1,2}/d{4},d{2}:d{2}:d{2})')
format = '%d/%m/%Y,%H:%M:%S'
datetime.strptime(datetime_pattern.search(line).group(), format)