Regex replace matches

Question

Assuming I have this entry in a dictionary:

'Michaele Frendu': ['Micheli Frendu', 'Michael', 'Michaele']

which means that for every instance of the value in the list, it has to be replaced by the key.

ie:

if I have this sample input:

s = 'concessit et assignavit Micheli Frendu presenti viridarium'

this would be replaced by:

s = 'concessit et assignavit Michaele Frendu presenti viridarium'

The problem is when I already have a Michaele Frendu in my text and Michaele is also an item in the list ex:

s = 'Pro Michaele Frendu contra Lucam Zamit'

This is changing to:

s = 'Pro Michaele Frendu Frendu contra Lucam Zamit'

where my desired output is:

s = 'Pro Michaele Frendu contra Lucam Zamit'

In this case I don't want any replacement as the value is already equal to the key.

I am using this regex pattern but is not working:

my_regex = r"\b(?=\w)" + re.escape(l) + r"\b(?!\w)"
s = re.sub(my_regex, k, s)

where k is the key and l is a value from the list

What about a mere postprocess like .replace('Frendu Frendu', 'Frendu')? How do you build the pattern and run replacements? Can you modify the dictionary values? — Wiktor Stribiżew
– Wiktor Stribiżew, Commented Oct 12, 2018 at 10:09

blhsing · Accepted Answer · 2018-10-12 10:22:00Z

1

You can simply place the replacement in the first of your regex alternation list, so that it will replace the replacement with itself, with higher precedence than the alternative keywords:

import re
d = {'Michaele Frendu': ['Micheli Frendu', 'Michael', 'Michaele']}
s = 'Pro Michaele Frendu contra Lucam Zamit'
for k, v in d.items():
    print(re.sub('|'.join(map(re.escape, (k, *v))), k, s))

This outputs:

Pro Michaele Frendu contra Lucam Zamit

And with s = 'concessit et assignavit Micheli Frendu presenti viridarium', this outputs:

concessit et assignavit Michaele Frendu presenti viridarium

For clarity, note that '|'.join(map(re.escape, (k, *v))) returns the following during the iteration:

Michaele\ Frendu|Micheli\ Frendu|Michael|Michaele

edited Oct 12, 2018 at 10:22

answered Oct 12, 2018 at 10:16

blhsing

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