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How can I compare strings in a case insensitive way in Python?
I would like to encapsulate comparison of a regular strings to a repository string, using simple and Pythonic code. I also would like to have ability to look up values in a dict hashed by strings using regular python strings.
Assuming ASCII strings:
string1 = 'Hello'
string2 = 'hello'
if string1.lower() == string2.lower():
print("The strings are the same (case insensitive)")
else:
print("The strings are NOT the same (case insensitive)")
As of Python 3.3, casefold() is a better alternative:
string1 = 'Hello'
string2 = 'hello'
if string1.casefold() == string2.casefold():
print("The strings are the same (case insensitive)")
else:
print("The strings are NOT the same (case insensitive)")
If you want a more comprehensive solution that handles more complex unicode comparisons, see other answers.
Comparing strings in a case insensitive way seems trivial, but it's not. I will be using Python 3, since Python 2 is underdeveloped here.
The first thing to note is that case-removing conversions in Unicode aren't trivial. There is text for which text.lower() != text.upper().lower(), such as "ß":
>>> "ß".lower()
'ß'
>>> "ß".upper().lower()
'ss'
But let's say you wanted to caselessly compare "BUSSE" and "Buße". Heck, you probably also want to compare "BUSSE" and "BUẞE" equal - that's the newer capital form. The recommended way is to use casefold:
str.casefold()
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. [...]
Do not just use lower. If casefold is not available, doing .upper().lower() helps (but only somewhat).
Then you should consider accents. If your font renderer is good, you probably think "ê" == "ê" - but it doesn't:
>>> "ê" == "ê"
False
This is because the accent on the latter is a combining character.
>>> import unicodedata
>>> [unicodedata.name(char) for char in "ê"]
['LATIN SMALL LETTER E WITH CIRCUMFLEX']
>>> [unicodedata.name(char) for char in "ê"]
['LATIN SMALL LETTER E', 'COMBINING CIRCUMFLEX ACCENT']
The simplest way to deal with this is unicodedata.normalize. You probably want to use NFKD normalization, but feel free to check the documentation. Then one does
>>> unicodedata.normalize("NFKD", "ê") == unicodedata.normalize("NFKD", "ê")
True
To finish up, here this is expressed in functions:
import unicodedata
def normalize_caseless(text):
return unicodedata.normalize("NFKD", text.casefold())
def caseless_equal(left, right):
return normalize_caseless(left) == normalize_caseless(right)
Using Python 2, calling .lower() on each string or Unicode object...
string1.lower() == string2.lower()
...will work most of the time, but indeed doesn't work in the situations #tchrist has described.
Assume we have a file called unicode.txt containing the two strings Σίσυφος and ΣΊΣΥΦΟΣ. With Python 2:
>>> utf8_bytes = open("unicode.txt", 'r').read()
>>> print repr(utf8_bytes)
'\xce\xa3\xce\xaf\xcf\x83\xcf\x85\xcf\x86\xce\xbf\xcf\x82\n\xce\xa3\xce\x8a\xce\xa3\xce\xa5\xce\xa6\xce\x9f\xce\xa3\n'
>>> u = utf8_bytes.decode('utf8')
>>> print u
Σίσυφος
ΣΊΣΥΦΟΣ
>>> first, second = u.splitlines()
>>> print first.lower()
σίσυφος
>>> print second.lower()
σίσυφοσ
>>> first.lower() == second.lower()
False
>>> first.upper() == second.upper()
True
The Σ character has two lowercase forms, ς and σ, and .lower() won't help compare them case-insensitively.
However, as of Python 3, all three forms will resolve to ς, and calling lower() on both strings will work correctly:
>>> s = open('unicode.txt', encoding='utf8').read()
>>> print(s)
Σίσυφος
ΣΊΣΥΦΟΣ
>>> first, second = s.splitlines()
>>> print(first.lower())
σίσυφος
>>> print(second.lower())
σίσυφος
>>> first.lower() == second.lower()
True
>>> first.upper() == second.upper()
True
So if you care about edge-cases like the three sigmas in Greek, use Python 3.
(For reference, Python 2.7.3 and Python 3.3.0b1 are shown in the interpreter printouts above.)
Section 3.13 of the Unicode standard defines algorithms for caseless
matching.
X.casefold() == Y.casefold() in Python 3 implements the "default caseless matching" (D144).
Casefolding does not preserve the normalization of strings in all instances and therefore the normalization needs to be done ('å' vs. 'å'). D145 introduces "canonical caseless matching":
import unicodedata
def NFD(text):
return unicodedata.normalize('NFD', text)
def canonical_caseless(text):
return NFD(NFD(text).casefold())
NFD() is called twice for very infrequent edge cases involving U+0345 character.
Example:
>>> 'å'.casefold() == 'å'.casefold()
False
>>> canonical_caseless('å') == canonical_caseless('å')
True
There are also compatibility caseless matching (D146) for cases such as '㎒' (U+3392) and "identifier caseless matching" to simplify and optimize caseless matching of identifiers.
I saw this solution here using regex.
import re
if re.search('mandy', 'Mandy Pande', re.IGNORECASE):
# is True
It works well with accents
In [42]: if re.search("ê","ê", re.IGNORECASE):
....: print(1)
....:
1
However, it doesn't work with unicode characters case-insensitive. Thank you #Rhymoid for pointing out that as my understanding was that it needs the exact symbol, for the case to be true. The output is as follows:
In [36]: "ß".lower()
Out[36]: 'ß'
In [37]: "ß".upper()
Out[37]: 'SS'
In [38]: "ß".upper().lower()
Out[38]: 'ss'
In [39]: if re.search("ß","ßß", re.IGNORECASE):
....: print(1)
....:
1
In [40]: if re.search("SS","ßß", re.IGNORECASE):
....: print(1)
....:
In [41]: if re.search("ß","SS", re.IGNORECASE):
....: print(1)
....:
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.
The usual approach is to uppercase the strings or lower case them for the lookups and comparisons. For example:
>>> "hello".upper() == "HELLO".upper()
True
>>>
How about converting to lowercase first? you can use string.lower().
a clean solution that I found, where I'm working with some constant file extensions.
from pathlib import Path
class CaseInsitiveString(str):
def __eq__(self, __o: str) -> bool:
return self.casefold() == __o.casefold()
GZ = CaseInsitiveString(".gz")
ZIP = CaseInsitiveString(".zip")
TAR = CaseInsitiveString(".tar")
path = Path("/tmp/ALL_CAPS.TAR.GZ")
GZ in path.suffixes, ZIP in path.suffixes, TAR in path.suffixes, TAR == ".tAr"
# (True, False, True, True)
You can mention case=False in the str.contains()
data['Column_name'].str.contains('abcd', case=False)
def search_specificword(key, stng):
key = key.lower()
stng = stng.lower()
flag_present = False
if stng.startswith(key+" "):
flag_present = True
symb = [',','.']
for i in symb:
if stng.find(" "+key+i) != -1:
flag_present = True
if key == stng:
flag_present = True
if stng.endswith(" "+key):
flag_present = True
if stng.find(" "+key+" ") != -1:
flag_present = True
print(flag_present)
return flag_present
Output:
search_specificword("Affordable housing", "to the core of affordable outHousing in europe")
False
search_specificword("Affordable housing", "to the core of affordable Housing, in europe")
True
from re import search, IGNORECASE
def is_string_match(word1, word2):
# Case insensitively function that checks if two words are the same
# word1: string
# word2: string | list
# if the word1 is in a list of words
if isinstance(word2, list):
for word in word2:
if search(rf'\b{word1}\b', word, IGNORECASE):
return True
return False
# if the word1 is same as word2
if search(rf'\b{word1}\b', word2, IGNORECASE):
return True
return False
is_match_word = is_string_match("Hello", "hELLO")
True
is_match_word = is_string_match("Hello", ["Bye", "hELLO", "#vagavela"])
True
is_match_word = is_string_match("Hello", "Bye")
False
Consider using FoldedCase from jaraco.text:
>>> from jaraco.text import FoldedCase
>>> FoldedCase('Hello World') in ['hello world']
True
And if you want a dictionary keyed on text irrespective of case, use FoldedCaseKeyedDict from jaraco.collections:
>>> from jaraco.collections import FoldedCaseKeyedDict
>>> d = FoldedCaseKeyedDict()
>>> d['heLlo'] = 'world'
>>> list(d.keys()) == ['heLlo']
True
>>> d['hello'] == 'world'
True
>>> 'hello' in d
True
>>> 'HELLO' in d
True
def insenStringCompare(s1, s2):
""" Method that takes two strings and returns True or False, based
on if they are equal, regardless of case."""
try:
return s1.lower() == s2.lower()
except AttributeError:
print "Please only pass strings into this method."
print "You passed a %s and %s" % (s1.__class__, s2.__class__)
This is another regex which I have learned to love/hate over the last week so usually import as (in this case yes) something that reflects how im feeling!
make a normal function.... ask for input, then use ....something = re.compile(r'foo*|spam*', yes.I)...... re.I (yes.I below) is the same as IGNORECASE but you cant make as many mistakes writing it!
You then search your message using regex's but honestly that should be a few pages in its own , but the point is that foo or spam are piped together and case is ignored.
Then if either are found then lost_n_found would display one of them. if neither then lost_n_found is equal to None. If its not equal to none return the user_input in lower case using "return lost_n_found.lower()"
This allows you to much more easily match up anything thats going to be case sensitive. Lastly (NCS) stands for "no one cares seriously...!" or not case sensitive....whichever
if anyone has any questions get me on this..
import re as yes
def bar_or_spam():
message = raw_input("\nEnter FoO for BaR or SpaM for EgGs (NCS): ")
message_in_coconut = yes.compile(r'foo*|spam*', yes.I)
lost_n_found = message_in_coconut.search(message).group()
if lost_n_found != None:
return lost_n_found.lower()
else:
print ("Make tea not love")
return
whatz_for_breakfast = bar_or_spam()
if whatz_for_breakfast == foo:
print ("BaR")
elif whatz_for_breakfast == spam:
print ("EgGs")
How can I compare strings in a case insensitive way in Python?
I would like to encapsulate comparison of a regular strings to a repository string, using simple and Pythonic code. I also would like to have ability to look up values in a dict hashed by strings using regular python strings.
Assuming ASCII strings:
string1 = 'Hello'
string2 = 'hello'
if string1.lower() == string2.lower():
print("The strings are the same (case insensitive)")
else:
print("The strings are NOT the same (case insensitive)")
As of Python 3.3, casefold() is a better alternative:
string1 = 'Hello'
string2 = 'hello'
if string1.casefold() == string2.casefold():
print("The strings are the same (case insensitive)")
else:
print("The strings are NOT the same (case insensitive)")
If you want a more comprehensive solution that handles more complex unicode comparisons, see other answers.
Comparing strings in a case insensitive way seems trivial, but it's not. I will be using Python 3, since Python 2 is underdeveloped here.
The first thing to note is that case-removing conversions in Unicode aren't trivial. There is text for which text.lower() != text.upper().lower(), such as "ß":
>>> "ß".lower()
'ß'
>>> "ß".upper().lower()
'ss'
But let's say you wanted to caselessly compare "BUSSE" and "Buße". Heck, you probably also want to compare "BUSSE" and "BUẞE" equal - that's the newer capital form. The recommended way is to use casefold:
str.casefold()
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. [...]
Do not just use lower. If casefold is not available, doing .upper().lower() helps (but only somewhat).
Then you should consider accents. If your font renderer is good, you probably think "ê" == "ê" - but it doesn't:
>>> "ê" == "ê"
False
This is because the accent on the latter is a combining character.
>>> import unicodedata
>>> [unicodedata.name(char) for char in "ê"]
['LATIN SMALL LETTER E WITH CIRCUMFLEX']
>>> [unicodedata.name(char) for char in "ê"]
['LATIN SMALL LETTER E', 'COMBINING CIRCUMFLEX ACCENT']
The simplest way to deal with this is unicodedata.normalize. You probably want to use NFKD normalization, but feel free to check the documentation. Then one does
>>> unicodedata.normalize("NFKD", "ê") == unicodedata.normalize("NFKD", "ê")
True
To finish up, here this is expressed in functions:
import unicodedata
def normalize_caseless(text):
return unicodedata.normalize("NFKD", text.casefold())
def caseless_equal(left, right):
return normalize_caseless(left) == normalize_caseless(right)
Using Python 2, calling .lower() on each string or Unicode object...
string1.lower() == string2.lower()
...will work most of the time, but indeed doesn't work in the situations #tchrist has described.
Assume we have a file called unicode.txt containing the two strings Σίσυφος and ΣΊΣΥΦΟΣ. With Python 2:
>>> utf8_bytes = open("unicode.txt", 'r').read()
>>> print repr(utf8_bytes)
'\xce\xa3\xce\xaf\xcf\x83\xcf\x85\xcf\x86\xce\xbf\xcf\x82\n\xce\xa3\xce\x8a\xce\xa3\xce\xa5\xce\xa6\xce\x9f\xce\xa3\n'
>>> u = utf8_bytes.decode('utf8')
>>> print u
Σίσυφος
ΣΊΣΥΦΟΣ
>>> first, second = u.splitlines()
>>> print first.lower()
σίσυφος
>>> print second.lower()
σίσυφοσ
>>> first.lower() == second.lower()
False
>>> first.upper() == second.upper()
True
The Σ character has two lowercase forms, ς and σ, and .lower() won't help compare them case-insensitively.
However, as of Python 3, all three forms will resolve to ς, and calling lower() on both strings will work correctly:
>>> s = open('unicode.txt', encoding='utf8').read()
>>> print(s)
Σίσυφος
ΣΊΣΥΦΟΣ
>>> first, second = s.splitlines()
>>> print(first.lower())
σίσυφος
>>> print(second.lower())
σίσυφος
>>> first.lower() == second.lower()
True
>>> first.upper() == second.upper()
True
So if you care about edge-cases like the three sigmas in Greek, use Python 3.
(For reference, Python 2.7.3 and Python 3.3.0b1 are shown in the interpreter printouts above.)
Section 3.13 of the Unicode standard defines algorithms for caseless
matching.
X.casefold() == Y.casefold() in Python 3 implements the "default caseless matching" (D144).
Casefolding does not preserve the normalization of strings in all instances and therefore the normalization needs to be done ('å' vs. 'å'). D145 introduces "canonical caseless matching":
import unicodedata
def NFD(text):
return unicodedata.normalize('NFD', text)
def canonical_caseless(text):
return NFD(NFD(text).casefold())
NFD() is called twice for very infrequent edge cases involving U+0345 character.
Example:
>>> 'å'.casefold() == 'å'.casefold()
False
>>> canonical_caseless('å') == canonical_caseless('å')
True
There are also compatibility caseless matching (D146) for cases such as '㎒' (U+3392) and "identifier caseless matching" to simplify and optimize caseless matching of identifiers.
I saw this solution here using regex.
import re
if re.search('mandy', 'Mandy Pande', re.IGNORECASE):
# is True
It works well with accents
In [42]: if re.search("ê","ê", re.IGNORECASE):
....: print(1)
....:
1
However, it doesn't work with unicode characters case-insensitive. Thank you #Rhymoid for pointing out that as my understanding was that it needs the exact symbol, for the case to be true. The output is as follows:
In [36]: "ß".lower()
Out[36]: 'ß'
In [37]: "ß".upper()
Out[37]: 'SS'
In [38]: "ß".upper().lower()
Out[38]: 'ss'
In [39]: if re.search("ß","ßß", re.IGNORECASE):
....: print(1)
....:
1
In [40]: if re.search("SS","ßß", re.IGNORECASE):
....: print(1)
....:
In [41]: if re.search("ß","SS", re.IGNORECASE):
....: print(1)
....:
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.
The usual approach is to uppercase the strings or lower case them for the lookups and comparisons. For example:
>>> "hello".upper() == "HELLO".upper()
True
>>>
How about converting to lowercase first? you can use string.lower().
a clean solution that I found, where I'm working with some constant file extensions.
from pathlib import Path
class CaseInsitiveString(str):
def __eq__(self, __o: str) -> bool:
return self.casefold() == __o.casefold()
GZ = CaseInsitiveString(".gz")
ZIP = CaseInsitiveString(".zip")
TAR = CaseInsitiveString(".tar")
path = Path("/tmp/ALL_CAPS.TAR.GZ")
GZ in path.suffixes, ZIP in path.suffixes, TAR in path.suffixes, TAR == ".tAr"
# (True, False, True, True)
You can mention case=False in the str.contains()
data['Column_name'].str.contains('abcd', case=False)
def search_specificword(key, stng):
key = key.lower()
stng = stng.lower()
flag_present = False
if stng.startswith(key+" "):
flag_present = True
symb = [',','.']
for i in symb:
if stng.find(" "+key+i) != -1:
flag_present = True
if key == stng:
flag_present = True
if stng.endswith(" "+key):
flag_present = True
if stng.find(" "+key+" ") != -1:
flag_present = True
print(flag_present)
return flag_present
Output:
search_specificword("Affordable housing", "to the core of affordable outHousing in europe")
False
search_specificword("Affordable housing", "to the core of affordable Housing, in europe")
True
from re import search, IGNORECASE
def is_string_match(word1, word2):
# Case insensitively function that checks if two words are the same
# word1: string
# word2: string | list
# if the word1 is in a list of words
if isinstance(word2, list):
for word in word2:
if search(rf'\b{word1}\b', word, IGNORECASE):
return True
return False
# if the word1 is same as word2
if search(rf'\b{word1}\b', word2, IGNORECASE):
return True
return False
is_match_word = is_string_match("Hello", "hELLO")
True
is_match_word = is_string_match("Hello", ["Bye", "hELLO", "#vagavela"])
True
is_match_word = is_string_match("Hello", "Bye")
False
Consider using FoldedCase from jaraco.text:
>>> from jaraco.text import FoldedCase
>>> FoldedCase('Hello World') in ['hello world']
True
And if you want a dictionary keyed on text irrespective of case, use FoldedCaseKeyedDict from jaraco.collections:
>>> from jaraco.collections import FoldedCaseKeyedDict
>>> d = FoldedCaseKeyedDict()
>>> d['heLlo'] = 'world'
>>> list(d.keys()) == ['heLlo']
True
>>> d['hello'] == 'world'
True
>>> 'hello' in d
True
>>> 'HELLO' in d
True
def insenStringCompare(s1, s2):
""" Method that takes two strings and returns True or False, based
on if they are equal, regardless of case."""
try:
return s1.lower() == s2.lower()
except AttributeError:
print "Please only pass strings into this method."
print "You passed a %s and %s" % (s1.__class__, s2.__class__)
This is another regex which I have learned to love/hate over the last week so usually import as (in this case yes) something that reflects how im feeling!
make a normal function.... ask for input, then use ....something = re.compile(r'foo*|spam*', yes.I)...... re.I (yes.I below) is the same as IGNORECASE but you cant make as many mistakes writing it!
You then search your message using regex's but honestly that should be a few pages in its own , but the point is that foo or spam are piped together and case is ignored.
Then if either are found then lost_n_found would display one of them. if neither then lost_n_found is equal to None. If its not equal to none return the user_input in lower case using "return lost_n_found.lower()"
This allows you to much more easily match up anything thats going to be case sensitive. Lastly (NCS) stands for "no one cares seriously...!" or not case sensitive....whichever
if anyone has any questions get me on this..
import re as yes
def bar_or_spam():
message = raw_input("\nEnter FoO for BaR or SpaM for EgGs (NCS): ")
message_in_coconut = yes.compile(r'foo*|spam*', yes.I)
lost_n_found = message_in_coconut.search(message).group()
if lost_n_found != None:
return lost_n_found.lower()
else:
print ("Make tea not love")
return
whatz_for_breakfast = bar_or_spam()
if whatz_for_breakfast == foo:
print ("BaR")
elif whatz_for_breakfast == spam:
print ("EgGs")
How can I compare strings in a case insensitive way in Python?
I would like to encapsulate comparison of a regular strings to a repository string, using simple and Pythonic code. I also would like to have ability to look up values in a dict hashed by strings using regular python strings.
Assuming ASCII strings:
string1 = 'Hello'
string2 = 'hello'
if string1.lower() == string2.lower():
print("The strings are the same (case insensitive)")
else:
print("The strings are NOT the same (case insensitive)")
As of Python 3.3, casefold() is a better alternative:
string1 = 'Hello'
string2 = 'hello'
if string1.casefold() == string2.casefold():
print("The strings are the same (case insensitive)")
else:
print("The strings are NOT the same (case insensitive)")
If you want a more comprehensive solution that handles more complex unicode comparisons, see other answers.
Comparing strings in a case insensitive way seems trivial, but it's not. I will be using Python 3, since Python 2 is underdeveloped here.
The first thing to note is that case-removing conversions in Unicode aren't trivial. There is text for which text.lower() != text.upper().lower(), such as "ß":
>>> "ß".lower()
'ß'
>>> "ß".upper().lower()
'ss'
But let's say you wanted to caselessly compare "BUSSE" and "Buße". Heck, you probably also want to compare "BUSSE" and "BUẞE" equal - that's the newer capital form. The recommended way is to use casefold:
str.casefold()
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. [...]
Do not just use lower. If casefold is not available, doing .upper().lower() helps (but only somewhat).
Then you should consider accents. If your font renderer is good, you probably think "ê" == "ê" - but it doesn't:
>>> "ê" == "ê"
False
This is because the accent on the latter is a combining character.
>>> import unicodedata
>>> [unicodedata.name(char) for char in "ê"]
['LATIN SMALL LETTER E WITH CIRCUMFLEX']
>>> [unicodedata.name(char) for char in "ê"]
['LATIN SMALL LETTER E', 'COMBINING CIRCUMFLEX ACCENT']
The simplest way to deal with this is unicodedata.normalize. You probably want to use NFKD normalization, but feel free to check the documentation. Then one does
>>> unicodedata.normalize("NFKD", "ê") == unicodedata.normalize("NFKD", "ê")
True
To finish up, here this is expressed in functions:
import unicodedata
def normalize_caseless(text):
return unicodedata.normalize("NFKD", text.casefold())
def caseless_equal(left, right):
return normalize_caseless(left) == normalize_caseless(right)
Using Python 2, calling .lower() on each string or Unicode object...
string1.lower() == string2.lower()
...will work most of the time, but indeed doesn't work in the situations #tchrist has described.
Assume we have a file called unicode.txt containing the two strings Σίσυφος and ΣΊΣΥΦΟΣ. With Python 2:
>>> utf8_bytes = open("unicode.txt", 'r').read()
>>> print repr(utf8_bytes)
'\xce\xa3\xce\xaf\xcf\x83\xcf\x85\xcf\x86\xce\xbf\xcf\x82\n\xce\xa3\xce\x8a\xce\xa3\xce\xa5\xce\xa6\xce\x9f\xce\xa3\n'
>>> u = utf8_bytes.decode('utf8')
>>> print u
Σίσυφος
ΣΊΣΥΦΟΣ
>>> first, second = u.splitlines()
>>> print first.lower()
σίσυφος
>>> print second.lower()
σίσυφοσ
>>> first.lower() == second.lower()
False
>>> first.upper() == second.upper()
True
The Σ character has two lowercase forms, ς and σ, and .lower() won't help compare them case-insensitively.
However, as of Python 3, all three forms will resolve to ς, and calling lower() on both strings will work correctly:
>>> s = open('unicode.txt', encoding='utf8').read()
>>> print(s)
Σίσυφος
ΣΊΣΥΦΟΣ
>>> first, second = s.splitlines()
>>> print(first.lower())
σίσυφος
>>> print(second.lower())
σίσυφος
>>> first.lower() == second.lower()
True
>>> first.upper() == second.upper()
True
So if you care about edge-cases like the three sigmas in Greek, use Python 3.
(For reference, Python 2.7.3 and Python 3.3.0b1 are shown in the interpreter printouts above.)
Section 3.13 of the Unicode standard defines algorithms for caseless
matching.
X.casefold() == Y.casefold() in Python 3 implements the "default caseless matching" (D144).
Casefolding does not preserve the normalization of strings in all instances and therefore the normalization needs to be done ('å' vs. 'å'). D145 introduces "canonical caseless matching":
import unicodedata
def NFD(text):
return unicodedata.normalize('NFD', text)
def canonical_caseless(text):
return NFD(NFD(text).casefold())
NFD() is called twice for very infrequent edge cases involving U+0345 character.
Example:
>>> 'å'.casefold() == 'å'.casefold()
False
>>> canonical_caseless('å') == canonical_caseless('å')
True
There are also compatibility caseless matching (D146) for cases such as '㎒' (U+3392) and "identifier caseless matching" to simplify and optimize caseless matching of identifiers.
I saw this solution here using regex.
import re
if re.search('mandy', 'Mandy Pande', re.IGNORECASE):
# is True
It works well with accents
In [42]: if re.search("ê","ê", re.IGNORECASE):
....: print(1)
....:
1
However, it doesn't work with unicode characters case-insensitive. Thank you #Rhymoid for pointing out that as my understanding was that it needs the exact symbol, for the case to be true. The output is as follows:
In [36]: "ß".lower()
Out[36]: 'ß'
In [37]: "ß".upper()
Out[37]: 'SS'
In [38]: "ß".upper().lower()
Out[38]: 'ss'
In [39]: if re.search("ß","ßß", re.IGNORECASE):
....: print(1)
....:
1
In [40]: if re.search("SS","ßß", re.IGNORECASE):
....: print(1)
....:
In [41]: if re.search("ß","SS", re.IGNORECASE):
....: print(1)
....:
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.
The usual approach is to uppercase the strings or lower case them for the lookups and comparisons. For example:
>>> "hello".upper() == "HELLO".upper()
True
>>>
How about converting to lowercase first? you can use string.lower().
a clean solution that I found, where I'm working with some constant file extensions.
from pathlib import Path
class CaseInsitiveString(str):
def __eq__(self, __o: str) -> bool:
return self.casefold() == __o.casefold()
GZ = CaseInsitiveString(".gz")
ZIP = CaseInsitiveString(".zip")
TAR = CaseInsitiveString(".tar")
path = Path("/tmp/ALL_CAPS.TAR.GZ")
GZ in path.suffixes, ZIP in path.suffixes, TAR in path.suffixes, TAR == ".tAr"
# (True, False, True, True)
You can mention case=False in the str.contains()
data['Column_name'].str.contains('abcd', case=False)
def search_specificword(key, stng):
key = key.lower()
stng = stng.lower()
flag_present = False
if stng.startswith(key+" "):
flag_present = True
symb = [',','.']
for i in symb:
if stng.find(" "+key+i) != -1:
flag_present = True
if key == stng:
flag_present = True
if stng.endswith(" "+key):
flag_present = True
if stng.find(" "+key+" ") != -1:
flag_present = True
print(flag_present)
return flag_present
Output:
search_specificword("Affordable housing", "to the core of affordable outHousing in europe")
False
search_specificword("Affordable housing", "to the core of affordable Housing, in europe")
True
from re import search, IGNORECASE
def is_string_match(word1, word2):
# Case insensitively function that checks if two words are the same
# word1: string
# word2: string | list
# if the word1 is in a list of words
if isinstance(word2, list):
for word in word2:
if search(rf'\b{word1}\b', word, IGNORECASE):
return True
return False
# if the word1 is same as word2
if search(rf'\b{word1}\b', word2, IGNORECASE):
return True
return False
is_match_word = is_string_match("Hello", "hELLO")
True
is_match_word = is_string_match("Hello", ["Bye", "hELLO", "#vagavela"])
True
is_match_word = is_string_match("Hello", "Bye")
False
Consider using FoldedCase from jaraco.text:
>>> from jaraco.text import FoldedCase
>>> FoldedCase('Hello World') in ['hello world']
True
And if you want a dictionary keyed on text irrespective of case, use FoldedCaseKeyedDict from jaraco.collections:
>>> from jaraco.collections import FoldedCaseKeyedDict
>>> d = FoldedCaseKeyedDict()
>>> d['heLlo'] = 'world'
>>> list(d.keys()) == ['heLlo']
True
>>> d['hello'] == 'world'
True
>>> 'hello' in d
True
>>> 'HELLO' in d
True
def insenStringCompare(s1, s2):
""" Method that takes two strings and returns True or False, based
on if they are equal, regardless of case."""
try:
return s1.lower() == s2.lower()
except AttributeError:
print "Please only pass strings into this method."
print "You passed a %s and %s" % (s1.__class__, s2.__class__)
This is another regex which I have learned to love/hate over the last week so usually import as (in this case yes) something that reflects how im feeling!
make a normal function.... ask for input, then use ....something = re.compile(r'foo*|spam*', yes.I)...... re.I (yes.I below) is the same as IGNORECASE but you cant make as many mistakes writing it!
You then search your message using regex's but honestly that should be a few pages in its own , but the point is that foo or spam are piped together and case is ignored.
Then if either are found then lost_n_found would display one of them. if neither then lost_n_found is equal to None. If its not equal to none return the user_input in lower case using "return lost_n_found.lower()"
This allows you to much more easily match up anything thats going to be case sensitive. Lastly (NCS) stands for "no one cares seriously...!" or not case sensitive....whichever
if anyone has any questions get me on this..
import re as yes
def bar_or_spam():
message = raw_input("\nEnter FoO for BaR or SpaM for EgGs (NCS): ")
message_in_coconut = yes.compile(r'foo*|spam*', yes.I)
lost_n_found = message_in_coconut.search(message).group()
if lost_n_found != None:
return lost_n_found.lower()
else:
print ("Make tea not love")
return
whatz_for_breakfast = bar_or_spam()
if whatz_for_breakfast == foo:
print ("BaR")
elif whatz_for_breakfast == spam:
print ("EgGs")
varA = 1
varB = 2
Code w/ Correct Result:
if type(varA) == type('a') or type(varB) == type('a'):
print "string involved (either varA or varB is a string)"
else:
print "varA and varB are not strings"
Code w/ Incorrect Result:
if type(varA) or type(varB) == type('a'):
print "string involved (either varA or varB is a string)"
else:
print "varA and varB are not strings"
Why exactly does the 2nd set of code not return the expected result (i.e. "varA and varB are not strings")? What is the step-by-step breakdown of what Python is doing with the 2nd set of code? I found a similar question had already been answered but did not entirely understand the explanation. Python: If-else statements.
In the second code snippet, the condition of the if-statement is being interpreted by Python like this:
if (type(varA)) or (type(varB) == type('a')):
Moreover, it will always evaluate to True.
This is because, no matter what the value of varA is, type(varA) evaluates to True:
>>> varA = 'a'
>>> bool(type(varA))
True
>>> varA = False
>>> bool(type(varA))
True
>>>
In fact, since Python's logical operators short-circuit (stop evaluating as soon as possible), the type(varB) == type('a') part of the condition will never even be evaluated.
On a separate note, you should be using is to compare types:
if type(varA) is str or type(varB) is str:
or, you can use isinstance:
if isinstance(varA, str) or isinstance(varB, str):
Your second example does not work because it parses as
if (type(varA)) or (type(varB) == type('a')):
and type(varA) will always be a class type which is considered True, so the whole expression will be True
There are better ways to do this
if any(isinstance(v, str) for v in (varA, varB)):
any takes an iterable and evaluates to True if anything in the iterable is true.
isinstance checks to see if the first argument "is a" second argument. Placing the generator expression inside of any reads as "if any v in (varA, varB) is a string): ... "
>>> var = 1
>>> isinstance(var, str) # var is an int, not a str
False
>>> isinstance(var, int)
True
>>> isinstance('a', int)
False
>>> isinstance('a', str) # 'a' is a str
True
iCodez is absolutely correct, but if you really want to do something along the lines of "list all elements and check if one of them is a string":
if str in map(type, [varA, varB]):
print "string involved"
Because in the second case you are not comparing both variables. Any integer above 0 would return True so you are not comparing types here.
if type(varA):
will always be True, because varA is equal to 1. You never even get to the second part of the condition.
I have a string, A = "abcdef", and several chars "a", "f" and "m". I want a condition to make sure none of the chars appears in A, i.e.,
if a not in A and f not in A and m not in A:
# do something
Is there a better way to do this? Thanks!
Sets are useful for this -- see the isdisjoint() method:
Return True if the set has no elements in common with other.
Sets are disjoint if and only if their intersection is the empty set.
new in version 2.6.
>>> a = "abcde"
>>> b = "ace"
>>> c = "xyz"
>>> set(a).isdisjoint(set(b))
False
>>> set(a).isdisjoint(set(c))
True
edit after comment
sets are still you friend. If I'm following you better now, you want this (or something close to it):
We'll just set everything up as sets to begin with for clarity:
>>> a = set('abcde')
>>> b = set('ace')
>>> c = set('acx')
If all of the chars in your set of characters is in the string, this happens:
>>> a.intersection(b) == b
True
If any of those characters are not present in your string, this happens:
>>> a.intersection(c) == c
False
Closer to what you need?
True in [i in 'abcdef' for i in 'afm']
gives True
and
True in [i in 'nopqrst' for i in 'afm']
gives False