Split string at nth occurrence of a given character

Question

Is there a Python-way to split a string after the nth occurrence of a given delimiter?

Given a string:

\'20_231_myString_234\'

It s

Answer 1

Using re to get a regex of the form ^((?:[^_]*_){n-1}[^_]*)_(.*) where n is a variable:

n=2
s='20_231_myString_234'
m=re.match(r'^((?:[^_]*_){%d}[^_]*)_(.*)' % (n-1), s)
if m: print m.groups()

or have a nice function:

import re
def nthofchar(s, c, n):
    regex=r'^((?:[^%c]*%c){%d}[^%c]*)%c(.*)' % (c,c,n-1,c,c)
    l = ()
    m = re.match(regex, s)
    if m: l = m.groups()
    return l

s='20_231_myString_234'
print nthofchar(s, '_', 2)

Or without regexes, using iterative find:

def nth_split(s, delim, n): 
    p, c = -1, 0
    while c < n:  
        p = s.index(delim, p + 1)
        c += 1
    return s[:p], s[p + 1:] 

s1, s2 = nth_split('20_231_myString_234', '_', 2)
print s1, ":", s2