replacing multiple instances of commas beginning at specific position
bokr at oz.net
Wed Nov 16 00:49:52 CET 2005
On Tue, 15 Nov 2005 08:26:22 GMT, Dennis Lee Bieber <wlfraed at ix.netcom.com> wrote:
>On 14 Nov 2005 09:43:57 -0800, "striker" <striker at trip.net> declaimed
>the following in comp.lang.python:
>> What would be the best approach to replace all instances of multiple
>> commas with just one comma, except for the 4 commas prior to ADMNSRC?
> Simplify the problem... Start by rephrasing... Since ADMNSRC is to
>always have four commas leading up to it (at least, as I understand your
>statement of intent), you could consider three of those to be part of
>the string. So...
> Phase one: split on commas, tossing out any null fields
> Phase two: replace "ADMNSRC" with ",,,ADMNSRC"
> Phase three: rejoin the parts that remain.
> Doing this efficiently may be another matter but...
>data = [ "one, two, three,,,,four,,,,ADMNSRC, five,,,,six",
> "one, two, three,four,,,,,,,,ADMNSRC,,,,,,eighteen, and so
>result = 
>for ln in data:
> wds = [x.strip() for x in ln.split(",") if x]
> for i in range(len(wds)):
> if wds[i] == "ADMNSRC":
> wds[i] = ",,,ADMNSRC"
Or if data is from a single file read, maybe (untested beyond what you see ;-)
>>> data = """\
... one, two, three,,,,four,,,,ADMNSRC, five,,,,six
... one, two, three,four,,,,,,,,ADMNSRC,,,,,,eighteen, and so on
>>> import re
>>> rxc = re.compile(',+')
>>> result = ',,,ADMNSRC'.join(','.join(rxc.split(s)) for s in data.split(',,,ADMNSRC'))
>>> print result
one, two, three,four,,,,ADMNSRC, five,six
one, two, three,four,,,,ADMNSRC,eighteen, and so on
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