Replace uppercase characters with lowercase+extra characters

Question

I am trying to find all the uppercase letters in a string and replace it with the lowercase plus underscore character. AFAIK there is no standard string function to achieve this (?)

For e.g. if the input string is 'OneWorldIsNotEnoughToLive' then the output string should be '_one_world_is_not_enough_to_live'

I am able to do it with the following piece of code:

# This finds all the uppercase occurrences and split into a list 
import re
split_caps = re.findall('[A-Z][^A-Z]*', name)
fmt_name = ''
for w in split_caps:
    fmt_name += '_' + w # combine the entries with underscore
fmt_name = fmt_name.lower() # Now change to lowercase
print (fmt_name)

I think this is too much. First re, followed by list iteration and finally converting to lowercase. Maybe there is a simpler way to achieve this, more pythonic and 1-2 lines.

Please suggest better solutions. Thanks.

Solution 1

Why not a simple regex:

import re
re.sub('([A-Z]{1})', r'_\1','OneWorldIsNotEnoughToLive').lower()

# result '_one_world_is_not_enough_to_live'

Solution 2

Try this.

string1 = "OneWorldIsNotEnoughToLive"
list1 = list(string1)
new_list = []
for i in list1:
    if i.isupper():
        i = "_"+i.lower()
    new_list.append(i)
print ''.join(new_list)

Output: _one_world_is_not_enough_to_live

Solution 3

string = input()

for letter in string:
    if letter.isupper():
        string = string.replace(letter, "_" + letter.lower())
print(string)

Comments

[jonrsharpe]

This isn't a code-writing service. Why don't you have a look at the str methods. "there is no standard string function" - what were you expecting, str.uppercase_to_lowercase_with_underscores?

[sk11]

I am aware that SO is not a code writing service. Just wanted to see if there are better solutions, more pythonic and 1-2 lines.

[jonrsharpe]

If you want working code reviewed, try codereview.stackexchange.com

[sk11]

@jonrsharpe Thanks for the link. I didn't know about codereview.stackexchange.com I will give it a look. By standard I meant replacing a string with some pattern.

[se7entyse7en]

This will replace consecutive uppercase characters with lowercase characters preceded by a single underscore. This should avoid it ([A-Z]{1})