I want to split alphabetical characters (letters) in a string using commas, but I also have non alphabetical characters that I want to preserve.
Examples (Input -> Desired Output):
"ABC" -> "A,B,C"
"-ABC" -> "-A,B,C"
"AB-C" -> "A,B,-C"
There can be maximum one "-" before a given letter.
My first attempt was using join method, but it would apply to any character of the string, whether is a letter or not.
e.g. ','.join("-ABC") gives "-,A,B,C" which is not what I want
Any suggestion?
Match the letters, but use a negative lookahead to exclude a letter at the end:
re.sub(r'([A-Z])(?!$)', r'\1,', inputstring)
See the online demo at regex101.com, this Python session:
>>> import re
>>> re.sub(r'([A-Z])(?!$)', r'\1,', 'ABC')
'A,B,C'
>>> re.sub(r'([A-Z])(?!$)', r'\1,', '-ABC')
'-A,B,C'
>>> re.sub(r'([A-Z])(?!$)', r'\1,', 'AB-C')
'A,B,-C'
r'\g<0>'
g and the angle brackets).This is probably a job for regex, but you can do it with .join, you just need to use a list comprehension with a test.
If the input string never ends in a non-alpha character you could do this:
data = ("ABC", "-ABC", "AB-C")
for s in data:
t = ''.join([c + ',' if c.isalpha() else c for c in s])[:-1]
print('{!r}\t-> {!r}'.format(s, t))
output
'ABC' -> 'A,B,C'
'-ABC' -> '-A,B,C'
'AB-C-' -> 'A,B,-C,-'
I admit that the [:-1] is a bit kludgy, but it's probably more efficient than doing an index check on every char to see if it's at the end of the string.
If the input string can end in a non-alpha character, we can do this:
data = ("ABC", "-ABC", "AB-C", "A-BC-")
for s in data:
t = ''.join([c + ',' if c.isalpha() else c for c in s[:-1]] + [s[-1]])
print('{!r}\t-> {!r}'.format(s, t))
output
'ABC' -> 'A,B,C'
'-ABC' -> '-A,B,C'
'AB-C' -> 'A,B,-C'
'A-BC-' -> 'A,-B,C,-'
Ok, it's probably kludgier than the first version, but hey, it works. :)
As I said earlier, a regex substitution is probably the sane way to do this.
I know that this is an old post, but isn't:
','.join('AB-C').replace('-,','-')
>>> A,B,-C
easier?
isalpha is a function that can be called on any string object will return bool value for checking if alphabet.
def split_char(s):
final = []
temp = ''
for i in s:
if i.isalpha():
final.append(temp+i)
temp = ''
else:
temp = temp + i
return final
print split_char('-ABC')
>>>['-A', 'B', 'C']
temp_list = split_char('AB-C')
print ','.join(temp_list)
>>> A,B,-C
