Is there a way in Python to have the following output?

Question

By using Python (mostly REGEX), I would like to have the following output:

string = 'leelee'
result = [('l',1),('e',2),('l',1),('e',2)]

The answer to "is it possible" is usually "yes" -- you're using a general-purpose language on a general-purpose computer, so you have full Turing potential. The implied question behind this, "how do I do it?" is an open-ended, individualized tutorial, which is *seriously* off-topic for Stack Overflow -- please re-take the [intro tour](https://stackoverflow.com/tour). — Prune, Nov 15 '19 at 00:40
Just loop over the string and count the number of occurrences. — LoMaPh, Nov 15 '19 at 00:40

score 1 · Answer 1 · answered Nov 15 '19 at 00:37

You can do it with the help of regex, but not regex alone.

First group by character, then list comprehension to count elements in those groups.

import re
s = 'leelee'
x = re.findall(r'(.)(\1*)',s)
print([[e[0],1+len(e[1])] for e in x])

The regex above captures a character (.), then matches that character any number of times if it immediately follows it (\1*).

score 0 · Answer 2 · answered Nov 15 '19 at 00:33

0

Why would you need regex? Python's * is string multiplication, and + is string concatenation. For example:

print("h" * 5) # hhhhh
print("h" + "t") # ht

answered Nov 15 '19 at 00:33

kkeey

Samwise · Answer 3 · 2019-11-15T00:39:25.947

0

Here's a version with a bunch of for loops:

for pair in result:
    for char, times in pair:
        for _ in range(times):
            print(char, end='')

Or here's one with comprehension and join:

print(''.join([x * y for x, y in result]))

Or the most direct solution:

print(string)

I don't think you'll find one that just uses regexes though...

edited Nov 15 '19 at 00:39

answered Nov 15 '19 at 00:37

Samwise

I have string as a input and want result as an output. – Farhaan Patel Nov 15 '19 at 00:39

wjandrea · Accepted Answer · 2019-11-15T01:10:29.053

0

You can do this with regex plus other tools, but it's not ideal. Using itertools.groupby is much easier.

from itertools import groupby
result = [(k, sum(1 for _ in g)) for k, g in groupby(string)]

This method of getting the len of an iterator is explained here.

edited Nov 15 '19 at 01:10

answered Nov 15 '19 at 00:42

wjandrea

4 Answers4