如何缩写字符串的第一个字符？

def first_lower(s):
if len(s) == 0:
return s
else:
return s[0].lower() + s[1:]


print first_lower("HELLO")  # Prints "hELLO"
print first_lower("")       # Doesn't crash  :-)

Simplest way:

>>> mystring = 'ABCDE'
>>> mystring[0].lower() + mystring[1:]
'aBCDE'
>>>

Update

See this answer (by @RichieHindle) for a more foolproof solution, including handling empty strings. That answer doesn't handle None though, so here is my take:

>>> def first_lower(s):
if not s: # Added to handle case where s == None
return
else:
return s[0].lower() + s[1:]


>>> first_lower(None)
>>> first_lower("HELLO")
'hELLO'
>>> first_lower("")
>>>

s = "Bobby tables"
s = s[0].lower() + s[1:]

Interestingly, none of these answers does exactly the opposite of capitalize(). For example, capitalize('abC') returns Abc rather than AbC. If you want the opposite of capitalize(), you need something like:

def uncapitalize(s):
if len(s) > 0:
s = s[0].lower() + s[1:].upper()
return s

I'd write it this way:

def first_lower(s):
if s == "":
return s
return s[0].lower() + s[1:]

This has the (relative) merit that it will throw an error if you inadvertently pass it something that isn't a string, like None or an empty list.

No need to handle special cases (and I think the symmetry is more Pythonic):

def uncapitalize(s):
return s[:1].lower() + s[1:].upper()

One-liner which handles empty strings and None:

func = lambda s: s[:1].lower() + s[1:] if s else ''


>>> func(None)
>>> ''
>>> func('')
>>> ''
>>> func('MARTINEAU')
>>> 'mARTINEAU'

This duplicate post lead me here.

If you've a list of strings like the one shown below

l = ['SentMessage', 'DeliverySucceeded', 'DeliveryFailed']

Then, to convert the first letter of all items in the list, you can use

l = [x[0].lower() + x[1:] for x in l]

Output

['sentMessage', 'deliverySucceeded', 'deliveryFailed']

pip install pydash first.

import pydash  # pip install pydash


assert pydash.lower_first("WriteLine") == "writeLine"

https://github.com/dgilland/pydash

https://pydash.readthedocs.io/en/latest/

https://pypi.org/project/pydash/