content/snippets/python/s/string-capitalize-camel-snake-kebab.md
---
title: Case conversion Python functions
shortTitle: Case conversion
type: story
language: python
tags: [string,regexp]
cover: digital-nomad-9
excerpt: Learn how to capitalize, camelcase, snake case, and kebab case strings in Python.
listed: false
dateModified: 2024-08-25
---
## Capitalize string
In order to capitalize the first letter of a string, you can use list slicing and the `str.upper()` method. Then, use `str.join()` to combine the capitalized first letter with the rest of the characters. Omit the `lower_rest` parameter to keep the rest of the string intact, or set it to `True` to convert to lowercase.
```py
def capitalize(s, lower_rest = False):
return ''.join([s[:1].upper(), (s[1:].lower() if lower_rest else s[1:])])
capitalize('fooBar') # 'FooBar'
capitalize('fooBar', True) # 'Foobar'
```
## Decapitalize string
To decapitalize the first letter of a string, you can use the exact same method as above, but with the `str.lower()` method instead of `str.upper()`.
```py
def decapitalize(s, upper_rest = False):
return ''.join([s[:1].lower(), (s[1:].upper() if upper_rest else s[1:])])
decapitalize('FooBar') # 'fooBar'
decapitalize('FooBar', True) # 'fOOBAR'
```
## Capitalize every word
To capitalize every word in a string, you can use the `str.title()` method.
```py
def capitalize_every_word(s):
return s.title()
capitalize_every_word('hello world!') # 'Hello World!'
```
## Camel case string
To convert a string to camel case, you can use `re.sub()` to replace any `-` or `_` with a space, using the regexp `r"(_|-)+"`. Then, use `str.title()` to capitalize every word and convert the rest to lowercase. Finally, use `str.replace()` to remove any spaces between words.
```py
from re import sub
def camel(s):
s = sub(r"(_|-)+", " ", s).title().replace(" ", "")
return ''.join([s[0].lower(), s[1:]])
camel('some_database_field_name') # 'someDatabaseFieldName'
camel('Some label that needs to be camelized')
# 'someLabelThatNeedsToBeCamelized'
camel('some-javascript-property') # 'someJavascriptProperty'
camel('some-mixed_string with spaces_underscores-and-hyphens')
# 'someMixedStringWithSpacesUnderscoresAndHyphens'
```
## Kebab case string
To kebab case a string, you'll use the same method as above, except replace `str.title()` with `re.sub()` to match all words in the string and then use `str.lower()` to convert them to lowercase. Finally, use `str.replace()` to replace spaces with `-`.
```py
from re import sub
def kebab(s):
return '-'.join(
sub(r"(\s|_|-)+"," ",
sub(r"[A-Z]{2,}(?=[A-Z][a-z]+[0-9]*|\b)|[A-Z]?[a-z]+[0-9]*|[A-Z]|[0-9]+",
lambda mo: ' ' + mo.group(0).lower(), s)).split())
kebab('camelCase') # 'camel-case'
kebab('some text') # 'some-text'
kebab('some-mixed_string With spaces_underscores-and-hyphens')
# 'some-mixed-string-with-spaces-underscores-and-hyphens'
kebab('AllThe-small Things') # 'all-the-small-things'
```
## Snake case string
To snake case a string, you can use the same method as above, but replace the `-` with `_`.
```py
from re import sub
def snake(s):
return '_'.join(
sub('([A-Z][a-z]+)', r' \1',
sub('([A-Z]+)', r' \1',
s.replace('-', ' '))).split()).lower()
snake('camelCase') # 'camel_case'
snake('some text') # 'some_text'
snake('some-mixed_string With spaces_underscores-and-hyphens')
# 'some_mixed_string_with_spaces_underscores_and_hyphens'
snake('AllThe-small Things') # 'all_the_small_things'
```