Suppose I have this:
My---sun--is------very-big---.
I want to replace all multiple hyphens with just one hyphen.
+10
A:
import re
astr='My---sun--is------very-big---.'
print(re.sub('-+','-',astr))
# My-sun-is-very-big-.
unutbu
2010-05-11 19:31:23
+1, but `-{2,}` would avoid replacing single `-` unnecessarily.
Tim Pietzcker
2010-05-12 08:37:51
+2
A:
How about:
>>> import re
>>> re.sub("-+", "-", "My---sun--is------very-big---.")
'My-sun-is-very-big-.'
the regular expression "-+" will look for 1 or more "-".
Charles Beattie
2010-05-11 19:34:13
+5
A:
If you really only want to coalesce hyphens, use the other suggestions. Otherwise you can write your own function, something like this:
>>> def coalesce(x):
... n = []
... for c in x:
... if not n or c != n[-1]:
... n.append(c)
... return ''.join(n)
...
>>> coalesce('My---sun--is------very-big---.')
'My-sun-is-very-big-.'
>>> coalesce('aaabbbccc')
'abc'
FogleBird
2010-05-11 19:55:15
+1 for a general solution. Since the OP used English words in their example, specifying a set of characters to coalesce (or not coalesce) would probably be preferable so as to avoid mangling words with double letters (i.e. letters -> leters).
tgray
2010-05-11 20:00:51
+5
A:
As usual, there's a nice itertools solution, using groupby:
>>> from itertools import groupby
>>> s = 'aaaaa----bbb-----cccc----d-d-d'
>>> ''.join(key for key, group in groupby(s))
'a-b-c-d-d-d'
Will McCutchen
2010-05-11 20:05:59
This solution doesn't answer the question if you only want to dedupe the hyphens. Is there an itertools solution that would keep 'aaaaa'?
mcpeterson
2010-05-11 22:18:06
@McPeterson: Sure, but they're not as nice. For just handling hyphens, you can do `''.join(key if key == '-' else ''.join(group) for key, group in groupby(s))`. For handling any non-alphanumeric character, `''.join(''.join(group) if key.isalnum() else key for key, group in groupby(s))`. But I'd just use one of the regex solutions instead.
Will McCutchen
2010-05-11 22:48:50
+11
A:
If you want to replace any run of consecutive characters, you can use
>>> import re
>>> a = "AA---BC++++DDDD-EE$$$$FF"
>>> print(re.sub(r"(.)\1+",r"\1",a))
A-BC+D-E$F
If you only want to coalesce non-word-characters, use
>>> print(re.sub(r"(\W)\1+",r"\1",a))
AA-BC+DDDD-EE$FF
If it's really just hyphens, I recommend unutbu's solution.
Tim Pietzcker
2010-05-11 20:10:57
+1
A:
How about an alternate without the re module:
'-'.join(filter(lambda w: len(w) > 0, 'My---sun--is------very-big---.'.split("-")))
Or going with Tim and FogleBird's previous suggestion, here's a more general method:
def coalesce_factory(x):
return lambda sent: x.join(filter(lambda w: len(w) > 0, sent.split(x)))
hyphen_coalesce = coalesce_factory("-")
hyphen_coalesce('My---sun--is------very-big---.')
Though personally, I would use the re module first :)
- mcpeterson
mcpeterson
2010-05-11 21:29:56