For instance, I have a string like this:
my_string = 'a hello aaaaa hi aaaaaaa bye bbb' I want to change 'a' or 'a's to 'b'. So output I want is:
changed_string = 'b hello b hi b bye bbb' I tried use replace and then making multiple 'b's to single 'b', but then it would effect multiple 'b's that were originally in the string.
I don't want an answer like do the first n characters.
Any suggestions?
>>> import re >>> my_string = 'a hello aaaaa hi aaaaaaa bye bbb' >>> re.sub(r'a+', 'b', my_string) 'b hello b hi b bye bbb' 
. is a special character which mactches any character except newline by default. Escape it with a backslash like \.+. You can see all the special chars here: docs.python.org/library/re.html. Also accept my answer if it helped you :Duse regular expression.
depending on your tools, it could be a one-liner or 2-3 line of code.
with vim
s/a+/b/g --
ohhh, didn't notice it was python. see jamylak's answer.
Without using regex you could do this, although I would rather use regex since it's much clearer and faster in this case.
>>> from itertools import groupby >>> my_string = 'a hello aaaaa hi aaaaaaa bye bbb' >>> ''.join(''.join(g) if k != 'a' else 'b' for k, g in groupby(my_string)) 'b hello b hi b bye bbb' >>> mystring = 'a hello aaaaa hi aaaaaaa bye bbb' >>> ' '.join('b' if set(i)==set(['a']) else i for i in mystring.split()) 'b hello b hi b bye bbb' Note that while this works with your example, it will not work with strings where the repeated character is part of a word, such as 'aaaaaz' - It will leave such words untouched, Which may or may not be desirable...
[, ] to make it a generator. edit: nvm I don't think it would be that inefficient but regex is certainly faster