regex doesn't match the required string, except others

Question

Im new to this wonderful site. Kudos to the team here! I'm a python beginner!

Im trying to match a string in a file. im using re.match. it does work for other strings in the file except the one im interested into.

file has:

Dumping
..
..
Dumped

coordinates (.. ..)
..
..
EOF

i tried below script:

import re

f1 = open("problem_statment", "r") 
f2 = open("outfile.txt", "w")

for line in f1:
   if re.match("coordinates", line):
      f2.write(line)

the outfile doesn't give me the result of 'coordinates' match.., where as if i replace 'coordinates' in above code to 'Dumping', it matches..

Im clueless why it isn't matching 'coordinates'. i want to print whole line.. please guide!

Thanks!

Can't reproduce from your input data. Are you sure about the input you've provided here is correct and exactly formatted? — heemayl, Feb 05 '18 at 22:33
Yes, its the same input in the file im giving. there is two spaces for coordinates like: space space coordinates : — TgP, Feb 05 '18 at 22:44

score 3 · Answer 1 · edited Feb 05 '18 at 22:31

3

You don't need to use the re module for this. You can just write

if 'coordinates' in line:
    f2.write(line)

edited Feb 05 '18 at 22:31

Matias Cicero

25,439
13
82
154

answered Feb 05 '18 at 22:29

rbennell

1,134
11
14

This will match anywhere in the line, not just start. You need `line.startswith('coordinate')`. – heemayl Feb 05 '18 at 22:32
True. but looking at the file in the example, i don't think that really matters. – rbennell Feb 05 '18 at 22:34
Yes, it worked. but im curios to know why re.match doesnt work here? – TgP Feb 05 '18 at 22:45

score 0 · Answer 2 · answered Feb 05 '18 at 22:32

0

Look at the difference between re.match and re.search. Look at this post https://stackoverflow.com/a/180993/8382967

answered Feb 05 '18 at 22:32

Mathieu Kb

23
4

score 0 · Answer 3 · answered Feb 06 '18 at 07:42

The problem with re.match is it only search at beginning of the string. Not in newlines . But your desired string is in newline.

You can use re.search() or re.findall() method.

import re
pattern=r'coordinates.+'
with open('file.txt','r') as f:
    print(re.findall(pattern,f.read()))

output:

['coordinatessss (.. ..)']

regex doesn't match the required string, except others

3 Answers3