On 11/16/2017 5:57 PM, Terry Reedy wrote:
On 11/16/2017 2:56 PM, Terry Reedy wrote:
Correct off-by-one error. I should have tested with an edge case such as
print(list(roundrobin('ABC', '')))
The following combines 3 statements into one for statement.
def roundrobin(*iterables):
"roundrobin('ABC', 'D', 'EF') --> A D E B F C"
nexts = cycle(iter(it).__next__ for it in iterables)
for reduced_len in reversed(range(1, len(iterables))):
Make that 0 rather than 1 for start value.
try:
for next in nexts:
yield next()
except StopIteration:
nexts = cycle(islice(nexts, reduced_len))
A slightly clearer, slightly less efficient alternative would be
def roundrobin(*iterables):
"roundrobin('ABC', 'D', 'EF') --> A D E B F C"
nexts = cycle(iter(it).__next__ for it in iterables)
for current_len in reversed(range(1, len(iterables)+1)):
try:
for next in nexts:
yield next()
except StopIteration:
nexts = cycle(islice(nexts, current_len - 1))
I submitted the 'current_len' version as
https://bugs.python.org/issue32099
"Use range in itertools roundrobin recipe"
--
Terry Jan Reedy
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