codefreak codefreak - 3 months ago 42
Python Question

Round Robin method of mixing of two lists in python

If input is

round_robin(range(5), "hello")


i need o/p as

[0, 'h', 1, 'e', 2, 'l', 3, 'l', 4, 'o']


I tried

def round_robin(*seqs):
list1=[]
length=len(seqs)
list1= cycle(iter(items).__name__ for items in seqs)
while length:
try:
for x in list1:
yield x
except StopIteration:
length -= 1

pass


but it gives error as

AttributeError: 'listiterator' object has no attribute '__name__'


How to modify the code to get the desired o/p

Answer

You could find a series of iteration recipes here: http://docs.python.org/2.7/library/itertools.html#recipes

from itertools import islice, cycle


def roundrobin(*iterables):
    "roundrobin('ABC', 'D', 'EF') --> A D E B F C"
    # Recipe credited to George Sakkis
    pending = len(iterables)
    nexts = cycle(iter(it).next for it in iterables)
    while pending:
        try:
            for next in nexts:
                yield next()
        except StopIteration:
            pending -= 1
            nexts = cycle(islice(nexts, pending))


print list(roundrobin(range(5), "hello"))