Reputation: 505
Say I have a text file with the line 'I like elephants'. If I cat the said file and the pipe it to 'grep elephants', I get the entire line "I like elephants".
How do I achieve this functionality in Python with re? Ive been trying the following:
test = re.search('elephants', 'I like elephants.\nThey are nice')
test.group(0)
I get only the word 'elephants' and not the whole sentence as the output.
How do I get the entire sentence? Thank you.
Upvotes: 29
Views: 72326
Reputation: 3022
You could use the in
keyword to check for your substring:
with open('text_file.txt', 'r') as f:
for line in f.readlines():
if 'elephant' in line:
print(line)
Or, if you had a string s
with \n
characters:
for line in s.split('\n'):
if 'elephant' in line:
print(line)
Your regex only prints elephant
because that's what it captured: exactly your regex string. If you were to try the following regex instead:
test = re.search(r'(.*?elephants.*?)\n', 'I like elephants.\nThey are nice')
Then you'd have results for test.group(0)
and test.group(1)
which include the whole line before and after the elephants.
In [22]: test.group(0)
Out[22]: 'I like elephants.\n'
That's the whole captured string.
In [23]: test.group(1)
Out[23]: 'I like elephants.'
That's just the capture group (string between parentheses).
Upvotes: 31