How to count the number of dashes between any two alphabetical characters?

Question

If we have a string of alphabetical characters and some dashes, and we want to count the number of dashes between any two alphabetic characters in this string. what is the easiest way to do this?

Example:

Input: a--bc---d-k

output: 2031

This means that there are 2 dashes between a and b, 0 dash between b and c, 3 dashes between c and d and 1 dash between d and k

what is a good way to find this output list in python?

Answer 1

You can use a very simple solution like this:

import re

s = 'a--bc---d-k'
# Create a list of dash strings.
dashes = re.split('[a-z]', s)[1:-1]
# Measure the length of each dash string in the list and join as a string.
results = ''.join([str(len(i)) for i in dashes])

Output:

'2031'

Answer 2

Solution with regex:

import re

x = 'a--bc---d-k'

results = [
    len(m) for m in
    re.findall('(?<=[a-z])-*(?=[a-z])', x)
]
print(results)
print(''.join(str(r) for r in results))

output:

[2, 0, 3, 1]
2031

---

Solution with brute force loop logic:

x = 'a--bc---d-k'

count = 0
results = []
for c in x:
    if c == '-':
        count += 1
    else:
        results.append(count)
        count = 0
results = results[1:]  # cut off first length
print(results)

output:

[2, 0, 3, 1]