Split strings and capture groups in Python

Question

I have the following string:

'Cc1cc([N+](=O)[O-])ccc1OCC(C)(O)CN1CCN(Cc2ccccc2)CC1'

and want to capture [N+] and [O-], that is, splitting and recovering them. I do not seem to be able to recover them by using re.split.

re.split(r'\[[^\]]*\]','Cc1cc([N+](=O)[O-])ccc1OCC(C)(O)CN1CCN(Cc2ccccc2)CC1')

output:
['Cc1cc(', '(=O)', ')ccc1OCC(C)(O)CN1CCN(Cc2ccccc2)CC1']

and I am looking for something like this:

['Cc1cc(', '[N+]','(=O)','[O-]', ')ccc1OCC(C)(O)CN1CCN(Cc2ccccc2)CC1']

I am aware of edits like: Splitting on regex without removing delimiters or In Python, how do I split a string and keep the separators?

You can use: re.findall(r'\[([^\]]*)\]','Cc1cc([N+](=O)[O-])ccc1OCC(C)(O)CN1CCN(Cc2ccccc2)CC1') — anubhava
– anubhava, Commented Dec 3, 2019 at 14:39
Use a capturing group \[([^\]]*)\] and match instead of splitting — The fourth bird
– The fourth bird, Commented Dec 3, 2019 at 14:39

Daniel · Accepted Answer · 2019-12-04 16:33:40Z

1

If you apply the function re.split wrapping your function with parenthesis you get the desired output:

s = 'Cc1cc([N+](=O)[O-])ccc1OCC(C)(O)CN1CCN(Cc2ccccc2)CC1'

re.split('(\[[^\]]*\])',s)

output : 
['Cc1cc(', '[N+]', '(=O)', '[O-]', ')ccc1OCC(C)(O)CN1CCN(Cc2ccccc2)CC1']

edited Dec 4, 2019 at 16:33

answered Dec 3, 2019 at 14:42

Daniel

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2 Comments

Daniel Over a year ago

I get this: ['Cc1cc(', '[N+]', '(=O)', '[O-]', ')ccc1OCC(C)(O)CN1CCN(Cc2ccccc2)CC1']

tobias_k Over a year ago

You might add a line or two of explanation, and show the actual result.

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