Python regular expression extract sub-strings from template

Question

In Python, I'm looking for a way to extract regex groups given a string and a matching template pattern, for example:

file_path = "/101-001-015_fg01/4312x2156/101-001-015_fg01.0001.exr"
file_template = "/{CODE}_{ELEMENT}/{WIDTH}x{HEIGHT}/{CODE}_{ELEMENT}.{FRAME}.exr"

The output I'm looking for is the following:

{
    "CODE": "101-001-015",
    "ELEMENT": "fg01",
    "WIDTH": "4312",
    "HEIGHT: "2156",
    "FRAME": "0001"
}

My initial approach was to format my template and find any and all matches, but it's not ideal:

import re
re_format = file_template.format(SHOT='(.*)', ELEMENT='(.*)', WIDTH='(.*)', HEIGHT='(.*)', FRAME='(.*)')
search = re.compile(re_format)
result = search.findall(file_path)
# result: [('101-001-015', 'fg01', '4312', '2156', '101-001-015', 'fg01.000', '')]

All template keys could be contain various characters and be of various lengths so I'm looking for a good matching algorithm. Any ideas if and how this could be done with Python re or any alternative libraries?

Thanks!

You would be interested in named capturing groups: see this partially complete regex _(?P<element>[^_]+)\.(?P<frame>\d+)\.exr$, put forth some more effort, and come back if you get stuck. — MonkeyZeus
– MonkeyZeus, Commented Mar 10, 2020 at 17:01

AnsFourtyTwo · Accepted Answer · 2020-03-10 17:11:08Z

2

I would go for named capturing groups and extract the desired results with the groupdict() function:

import re

file_path = "/101-001-015_fg01/4312x2156/101-001-015_fg01.0001.exr"
rx = r"\/(?P<CODE>.+)_(?P<ELEMENT>.+)\/(?P<WIDTH>.+)x(?P<HEIGHT>.+)\/.+\.(?P<FRAME>\w+).exr"
m = re.match(rx, file_path)

result = m.groupdict()
# {'CODE': '101-001-015', 'ELEMENT': 'fg01', 'WIDTH': '4312', 'HEIGHT': '2156', 'FRAME': '0001'}

answered Mar 10, 2020 at 17:11

AnsFourtyTwo

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A l w a y s S u n n y · Accepted Answer · 2020-03-10 17:26:42Z

1

Kind of similar like Simon did, I'll also try with named captured group

import re
regex = r"(?P<CODE>[0-9-]+)_(?P<ELEMENT>[0-9a-z]+)\/(?P<WIDTH>[0-9]+)x(?P<HEIGHT>[0-9]+)\/\1_\2\.(?P<FRAME>[0-9]+)\.exr"
test_str = "101-001-015_fg01/4312x2156/101-001-015_fg01.0001.exr"
matches = re.match(regex, test_str)
print(matches.groupdict())

DEMO: https://rextester.com/BEZH21139

answered Mar 10, 2020 at 17:26

A l w a y s S u n n y

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