python正则表达式用跳过模式拆分某些模式

Question

I want to split a Python string on certain patterns but not others. For example, I have the string

Joe, Dave, Professional, Ph.D. and Someone else

I want to split on \\sand\\s and , , but not , Ph.D.

How can this be accomplished in Python regex?

Answer 1

You can use:

re.split(r'\s+and\s+|,(?!\s*Ph\.D\.)\s*', 'Joe, Dave, Professional, Ph.D. and Someone else')

Result:

['Joe', 'Dave', 'Professional, Ph.D.', 'Someone else']

Answer 2

You can basically do this with either regular expressions or just regular string manipulation operations, (ie str.split() )

Here's an example that shows you how to do this using just regular string manipulation operations:

>>> DATA = 'Joe, Dave, Professional, Ph.D. and Someone else'
>>> IGNORE_THESE = frozenset([',', 'and'])

>>> PRUNED_DATA = [d.strip(',') for d in DATA.split(' ') if d not in IGNORE_THESE]
>>>> print PRUNED_DATA
['Joe', 'Dave', 'Professional', 'Ph.D.', 'Someone', 'else']

I'm sure there is going to be some complex regular expression you can use, but this seems very straight forward for me and quite maintainable.

I hope you're not trying to parse natural language, for that, I would use some other library like NLTK

Answer 3

import re

DATA = 'Joe, Dave, Professional, Ph.D. and Someone else'

regx = re.compile('\s*(?:,|and)\s*')

print regx.split(DATA)

result

['Joe', 'Dave', 'Professional', 'Ph.D.', 'Someone else']

Where's the difficulty ?

Note that with (?:,|and) the delimiters don't appear in the result, while with (;|and) the result would be

['Joe', ',', 'Dave', ',', 'Professional', ',', 'Ph.D.', 'and', 'Someone else'] 

Edit 1

errrr.... the difficulty is that with

DATA = 'Joe, Dave, Professional, Handicaped, Ph.D. and Someone else'

the result is

['Joe', 'Dave', 'Professional', 'H', 'icaped', 'Ph.D.', 'Someone else']

.

Corrected:

regx = re.compile('\s+and\s+|\s*,\s*')

.

Edit 2

errrr.. ahem... ahem...

Sorry, I hadn't noticed that Professional, Ph.D. must not be splitted. But what is the criterion to not split according the comma in this string ?

I choosed this criterion: "a comma not followed by a string having dots before the next comma"

Another problem is if whitespaces and word 'and' are mixed.

And there's also the problem of heading and trailing whitespaces.

Finally I succeeded to write a regex' pattern that manages much more cases than the previous one, even if some cases are somewhat artificial (like lost 'and' present at the end of a string; why not at the beginning too, also ? etc) :

import re

regx = re.compile('\s*,(?!(?:[^,.]+?\.)+[^,.]*?,)(?:\sand[,\s]+|\s)*|\s*and[,\s]+|[.\s]*\Z|\A\s*')

DATA = '   Joe ,and, Dave , Professional, Ph.D., Handicapped   and handyman  , and   Someone else  and  . .'
print repr(DATA)
print
print regx.split(DATA)

result

'   Joe ,and, Dave , Professional, Ph.D., Handicapped   and handyman  , and   Someone else  and  . .'

['', 'Joe', '', 'Dave', 'Professional, Ph.D.', 'Handicapped', 'handyman', 'Someone else', '', '']

.

With print [x for x in regx.split(DATA) if x] , we obtain:

['Joe', 'Dave', 'Professional, Ph.D.', 'Handicapped', 'handyman', 'Someone else']

.

Compared to result of Qtax's regex on the same string:

['   Joe ', 'and', 'Dave ', 'Professional, Ph.D.', 'Handicapped', 'handyman  ', 'and   Someone else', '. .']