CODEWITHSUNDEEP
pythonregexindexing
xitrium
xitrium

Reputation: 4385

Find the indexes of all regex matches?

I'm parsing strings that could have any number of quoted strings inside them (I'm parsing code, and trying to avoid PLY). I want to find out if a substring is quoted, and I have the substrings index. My initial thought was to use re to find all the matches and then figure out the range of indexes they represent.

It seems like I should use re with a regex like \"[^\"]+\"|'[^']+' (I'm avoiding dealing with triple quoted and such strings at the moment). When I use findall() I get a list of the matching strings, which is somewhat nice, but I need indexes.

My substring might be as simple as c, and I need to figure out if this particular c is actually quoted or not.

Upvotes: 122

Views: 163973

Answers (3)

Omkar Rahane
Omkar Rahane

Reputation: 124

This should solve your issue:

pattern=r"(?=(\"[^\"]+\"|'[^']+'))"

Then use the following to get all overlapping indices:

indicesTuple = [(mObj.start(1),mObj.end(1)-1) for mObj in re.finditer(pattern,input)]

Upvotes: 1

Be Champzz
Be Champzz

Reputation: 929

To get indice of all occurences:

S = input() # Source String 
k = input() # String to be searched
import re
pattern = re.compile(k)
r = pattern.search(S)
if not r: print("(-1, -1)")
while r:
    print("({0}, {1})".format(r.start(), r.end() - 1))
    r = pattern.search(S,r.start() + 1)

Upvotes: 6

Dave Kirby
Dave Kirby

Reputation: 26552

This is what you want: (source)

re.finditer(pattern, string[, flags])

Return an iterator yielding MatchObject instances over all non-overlapping matches for the RE pattern in string. The string is scanned left-to-right, and matches are returned in the order found. Empty matches are included in the result unless they touch the beginning of another match.

You can then get the start and end positions from the MatchObjects.

e.g.

[(m.start(0), m.end(0)) for m in re.finditer(pattern, string)]

Upvotes: 244

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