Multiline replace with python regular expression

Question

I have a repeating text in a large file which I want to replace with some other text. For example:

some text.......\n partition by range (STRT_DTTM)\n some more text......\n ); I want to use regex to find these blocks that start with partition by range and ends with ); and replace that block with 'THIS IS TEST'. I am using the below code import re

with open(r"C:\Users\x217838\Desktop\python\input.txt","rt") as in_file:
    text = in_file.read()
    s = re.compile("^partition by range(.*);\)$)",re.MULTILINE)
    replace = re.sub(s, 'THIS IS TEST', text)
    print(replace)

Can you please let me know where I am going wrong.

Jean-François Fabre · Accepted Answer · 2019-01-18 17:03:41Z

2

You have to use \ for all regex reserved symbols --> [\^$.|?*+(){}. The final code will be:

import re
text = "partition by range(CANE) uno"
s = re.compile("^partition by range\(.*\)",re.MULTILINE)
replace = re.sub(s, 'THIS IS TEST', text)
print(replace)

The result is:

THIS IS TEST uno

edited Jan 18, 2019 at 17:03

Jean-François Fabre♦

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answered Jan 18, 2019 at 16:40

Marco Visibelli

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5 Comments

Jean-François Fabre Over a year ago

That works, but I would have liked to have an explanation on why you escape the parentheses in your answer.

Marco Visibelli Over a year ago

The reason is that '(' and ')' are reserved symbol, used internally by regex. if you want to use the actual char you have to use the escape

Marco Visibelli Over a year ago

You have to use \ for all this symbols --> [\^$.|?*+(){}

Jean-François Fabre Over a year ago

I know. I meant in the answer. comments aren't made for that.

Imtiyaz Ali Over a year ago

Can you show that with a multiline? The block ends with ); use this text please text = partition by range(CANE) uno blah blah blah blah blahhh );

Pushpesh Kumar Rajwanshi · Accepted Answer · 2019-01-18 17:45:33Z

1

If you have your text spanning across multiple lines something like this,

some text.......
partition by range (STRT_DTTM)
some more text......
);

Then you will have to use (?s) modifier to enable . matching a new line.

Demo

Sample python codes,

import re

s = '''some text.......
partition by range (STRT_DTTM)
some more text......
);'''

mods = re.sub(r'(?s)partition by range(.*?)\);','THIS IS TEST',s)
print(mods)

Prints,

some text.......
THIS IS TEST

edited Jan 18, 2019 at 17:45

answered Jan 18, 2019 at 17:28

Pushpesh Kumar Rajwanshi

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3 Comments

Imtiyaz Ali Over a year ago

Thank you !!! This is working but it is matching till the last ); Is there a way to match in non greedy way . Stop matching as soon as it finds the first pattern and replace it and start looking for the next pattern.

Pushpesh Kumar Rajwanshi Over a year ago

Sure, just change .* to .*? in the regex. Let me update my answer

Imtiyaz Ali Over a year ago

I got it . THANK YOU VERYYY MUCH.

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