Solving split string in python without the use of split() function

Question

Faced an interview question in Python that was as follow?

ex: 
input = (\'192.168.15.1\', \'.\', -1) ===> output = (192, 168, 15, 1)
input = (\'192.168.15         


        

Answer 1

You could solve this task with following function

def split_string(istr,ich,inte):
    res = []
    prev = 0
    for i,ch in enumerate(istr):
        if ch == ich:
            res.append(istr[prev:i])
            prev = i+1
            inte = inte-1
            if inte == 0:
                break            
    if prev < len(istr):
        res.append(istr[prev:])
    return res

or another solution

def split_string(istr,ich,inte):
    res = []
    h,_,r = istr.partition(ich)
    while r:
        res.append(h)
        inte = inte-1
        if inte == 0:
            h = r
            break               
        h,_,r = r.partition(ich)
    if h:
        res.append(h)
    return res

For following code

print split_string('192.168.15.1', '.', -1)
print split_string('192.168.15.1', '.', 2)

output will be

['192', '168', '15', '1']
['192', '168', '15.1']

Answer 2

Something like this would work:

def splitter(string_, splitchar, maxsplits):
    # if maxsplits is positive, split string  into maxsplits of parts, on splitchar.
    # Otherwise perform as many splits as the string allows.
    out = []
    sub = []
    for ch in string_:
        if ch != splitchar:
            sub.append(ch)
        else:
            if maxsplits < 1 or (maxsplits > 0 and (len(out) < maxsplits)):
                out.append(''.join(sub))
                sub = []
            else:
                sub.append(ch)
    out.append(''.join(sub))
    return tuple(out)


>>> splitter.splitter('192.168.15.1', '.', -1)
('192', '168', '15', '1')
>>> splitter.splitter('192.168.15.1', '.', 2)
('192', '168', '15.1')
>>> splitter.splitter('192.168.15.1', '.', 0)
('192', '168', '15', '1')
>>> splitter.splitter('192.168.15.1', '.', 1)
('192', '168.15.1')

Answer 3

Simple and recursive.

def split_str(s,c,i):
    if i == 0:
        return [s]
    else:
        head, _, rest = s.partition(c)
        if rest:
            return [head] + split_str(rest, c, i - 1)
        return [head]

Answer 4

def split(text, sep, maxsplit=-1):
    parts = []
    end = -1
    while True:
        start = end + 1
        end = text.find(sep, start)
        if (end == -1) or (maxsplit == 0):
            parts.append(text[start:])
            break
        else:
            parts.append(text[start:end])
            if maxsplit != 0: maxsplit -= 1
    return parts

print(split('192.168.15.1', '.', -1))  # ['192', '168', '15', '1']
print(split('192.168.15.1', '.', 2))  # ['192', '168', '15.1']

Answer 5

another simpler and short approach is you can use regular expressions like this:

import re
def split_without_using_split_fn(s, c, i):
    if i<=0:
        print(re.findall("[^"+c+"]+(?=\\"+c+"|$)", s))
    else:
        l=re.findall("[^"+c+"]+(?=\\"+c+"|$)", s)
        print(l[0:-i]+[c.join(l[i:])])

split_without_using_split_fn(*('192.168.15.1', '.', -1))
split_without_using_split_fn(*('192.168.15.1', '.', 2))

Output:

$ python3 p.py 
['192', '168', '15', '1']
['192', '168', '15.1']
$