How do I use regex to get the key information from a string in Python?

Question

I have a string where I want to extract the key information from:

gbk_kings_common_20171201_20180131_66000.0k_2017-12-01_TO_2018-01-31_id12_1277904128.csv

Namely, I would like to find the following:

File identifier, e.g. gbk_kings_common_20171201_20180131
Size, e.g. 330.0k
Date, e.g. 2017-12-01_TO_2018-02-31
Type of id, e.g. id12_12771231518

But I'm having a difficulty compiling the regex since the file identifier can always change in the length, although the rest of the information is pretty fixed when delimited by commas.

Do you have any control on the string? In such case, it is much easier if you change the character separating the different parts, since having _ both inside the identifier and between different parts of the string makes it much more difficult. — bracco23
– bracco23, Commented Aug 29, 2018 at 7:45
Could you specify how the file identifier varies? Does it simply add more dates? — DocDriven
– DocDriven, Commented Aug 29, 2018 at 7:47

Sunitha · Accepted Answer · 2018-08-29 07:47:53Z

4

You can use the pattern r'(.*)_(.*)_([\d-]+_TO_[\d-]+)_(id[\d_]*) to search your string.

>>> import re
>>> s = "gbk_kings_common_20171201_20180131_66000.0k_2017-12-01_TO_2018-01-31_id12_1277904128.csv"
>>> sre = re.search(r'(.*)_(.*)_([\d-]+_TO_[\d-]+)_(id[\d_]*)', s)
>>> file_id, size, date, type_id = sre.groups()
>>> print (file_id, size, date, type_id)
gbk_kings_common_20171201_20180131 66000.0k 2017-12-01_TO_2018-01-31 id12_1277904128

answered Aug 29, 2018 at 7:47

Sunitha

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2 Comments

winnie99 Over a year ago

I can see that gbk_kings_common_20171201_20180131_66000.0k_ refers to the groups (.*)_(.*) but how do you know that the second (.*) refer to 66000.0k and not something like 20171201_20180131_66000.0k?

Sunitha Over a year ago

@winnie99. If it matches 20171201_20180131, then the next pattern ([\d-]+_TO_[\d-]+) wouldn't match. So the first (.*), would match everything upto the last but one _ before the dates

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