How to match a substring in a string, ignoring case

Question

I’m looking for ignore case string comparison in Python.

I tried with:

if line.find('mandy') >= 0:

but no success for ignore case. I need to find a set of words in a given text file. I am reading the file line by line. The word on a line can be mandy, Mandy, MANDY, etc. (I don’t want to use toupper/tolower, etc.).

I’m looking for the Python equivalent of the Perl code below.

if ($line=~/^Mandy Pande:/i)

Asked By: Mandar Pande

||

Source

Answer 1

There’s another post here. Try looking at this.

BTW, you’re looking for the .lower() method:

string1 = "hi"
string2 = "HI"
if string1.lower() == string2.lower():
    print "Equals!"
else:
    print "Different!"

Answered By: Samuele Mattiuzzo

Answer 2

If you don’t want to use str.lower(), you can use a regular expression:

import re

if re.search('mandy', 'Mandy Pande', re.IGNORECASE):
    # Is True

Answered By: eumiro

Answer 3

import re
if re.search('(?i)Mandy Pande:', line):
    ...

Answered By: a'r

Answer 4

See this.

In [14]: re.match("mandy", "MaNdY", re.IGNORECASE)
Out[14]: <_sre.SRE_Match object at 0x23a08b8>

Answered By: Fredrik Pihl

Answer 5

a = "MandY"
alow = a.lower()
if "mandy" in alow:
    print "true"

work around

Answered By: Riccardo B.

Answer 6

Try:

if haystackstr.lower().find(needlestr.lower()) != -1:
  # True

Answered By: norbertoisaac

Answer 7

you can also use: s.lower() in str.lower()

Answered By: pabloverd

Answer 8

You can use in operator in conjunction with lower method of strings.

if "mandy" in line.lower():

Answered By: VHS

Answer 9

If it is a pandas series, you can mention case=False in the str.contains

data['Column_name'].str.contains('abcd', case=False)

OR if it is just two string comparisons try the other method below

You can use casefold() method. The casefold() method ignores cases when comparing.

firstString = "Hi EVERYONE"
secondString = "Hi everyone"

if firstString.casefold() == secondString.casefold():
    print('The strings are equal.')
else:
    print('The strings are not equal.')

Output:

The strings are equal.

Answered By: mpriya

Answer 10

One can use the in operator after applying str.casefold to both strings.

str.casefold is the recommended method for use in case-insensitive comparison.

Return a casefolded copy of the string. Casefolded strings may be used for caseless matching.

Casefolding is similar to lowercasing but more aggressive because it is intended to remove all case distinctions in a string. For example, the German lowercase letter ‘ß’ is equivalent to "ss". Since it is already lowercase, lower() would do nothing to ‘ß’; casefold() converts it to "ss".

The casefolding algorithm is described in section 3.13 of the Unicode Standard.

New in version 3.3.

For case-insensitive substring search:

needle = "TEST"
haystack = "testing"
if needle.casefold() in haystack.casefold():
    print('Found needle in haystack')

For case-insensitive string comparison:

a = "test"
b = "TEST"
if a.casefold() == b.casefold():
    print('a and b are equal, ignoring case')

Answered By: Unmitigated

How to match a substring in a string, ignoring case

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