Python/Re

Regular expressions in Python.

Extracting substring from strings using re

Suppose we have a string like "thing2_2017-04-09_05-04-67.csv" and we want to extract tokens from the filename (thing2, 2017, 04, 09, etc).

To extract particular tokens using a regular expression, we can use re.findall(regular_expression,string). For example, the regular expression [0-9]{4} looks for the digits 0-9 occurring exactly 4 times.

>>> z = "thing2_2017-04-09_05-04-67.csv"
>> re.findall(r'[0-9]{4}', z)
['2017']