CODEWITHSUNDEEP
pythonregexpython-2.7
Irshad Bhat
Irshad Bhat

Reputation: 8709

Why my regex replaces match pattern with function object rather than the replacement value?

I need a regex that takes the replacement pattern from a dictionary. I wrote the following code but the pattern gets replaced by the function object rather than the replacement value. 

>>> import re
>>> d1 = {'a':'1'}
>>> d2 = {'w':'2','k':'2'}
>>> re.sub(r'(a)([wk])', '%s%s' %(lambda m:d1[m.group()[0]], lambda m:d2[m.group()[1]]), 'waka')
'w<function <lambda> at 0x7f1e281efc08><function <lambda> at 0x7f1e281efcf8>a'

Expected output is 'w12a'.

Upvotes: 1

Views: 32

Answers (1)

falsetru
falsetru

Reputation: 369444

Becasue:

>>> import re
>>> '%s%s' %(lambda m:d1[m.group()[0]], lambda m:d2[m.group()[1]])
'<function <lambda> at 0x0000000002AB0128><function <lambda> at 0x0000000002AB0198>'

You're passing the above string as a replacement string.

Use replacement function as follow:

>>> import re
>>> d1 = {'a':'1'}
>>> d2 = {'w':'2','k':'2'}
>>> re.sub(r'(a)([wk])',
...        lambda m: d1[m.group(1)] + d2[m.group(2)],
...        'waka')
'w12a'

Upvotes: 1

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