Python: find a list within members of another list(in order)

Question

If I have this:

a=\'abcdefghij\'
b=\'de\'

Then this finds b in a:

b in a => True

Is there a way of doi

Answer 1

I think this will be faster - It uses C implementation list.index to search for the first element, and goes from there on.

def find_sublist(sub, bigger):
    if not bigger:
        return -1
    if not sub:
        return 0
    first, rest = sub[0], sub[1:]
    pos = 0
    try:
        while True:
            pos = bigger.index(first, pos) + 1
            if not rest or bigger[pos:pos+len(rest)] == rest:
                return pos
    except ValueError:
        return -1

data = list('abcdfghdesdkflksdkeeddefaksda')
print find_sublist(list('def'), data)

Note that this returns the position of the sublist in the list, not just True or False. If you want just a bool you could use this:

def is_sublist(sub, bigger): 
    return find_sublist(sub, bigger) >= 0