Find two strings next to a keyword with re in python

Question

I need to find two strings next to a keyword. Here is an example string

\plottwo{image1}{image2}

the keyword is \\plottwo and the correct result is

[image1, image2]

I know that if there is only one string next to the keyword I can use

re.findall('\plottwo.*?{(.*?)},text)

how can I extend this to two strings?

Answer 1

Note that this matches exactly two image strings:

import re

matcher = re.compile(r"""\\plottwo   # The literal \plottwo
                         {           # Opening brace for the first image group
                          (          # Start the first capture group
                           [^}]+     # Match anything OTHER than a closing brace
                          )          # End the first capture group
                         }           # Closing brace
                         {           # Opening brace for the second image group
                          (          # Start the second capture group
                           [^}]+     # Match anything OTHER than a closing brace
                          )          # End the second capture group
                         }           # Closing brace
                      """, re.VERBOSE)

print matcher.findall('\\plottwo{image1}{image2}')

If you wish to capture either one or two image strings, make one of the capture groups optional:

import re

matcher = re.compile(r"""\\plottwo   # The literal \plottwo
                         {           # Opening brace for the first image group
                          (          # Start the first capture group
                           [^}]+     # Match anything OTHER than a closing brace
                          )          # End the first capture group
                         }           # Closing brace
                         (?:         # Non-saving group that we can make optional
                            {        # Opening brace for the second image group
                             (       # Start the second capture group
                              [^}]+  # Match anything OTHER than a closing brace
                             )       # End the second capture group
                            }        # Closing brace
                         )?          # End the non-capturing group
                      """, re.VERBOSE)

print matcher.findall('\\plottwo{image1}{image2}')
print matcher.findall('\\plottwo{image2}')

But to echo one of the comments, regex is typically not the best way to do complex parsing jobs (and sometimes even simple parsing jobs :-).