Re: best cumulative sum


"Peter Otten" <__peter__@xxxxxx> wrote in message
news:dm263o$b8b$02$1@xxxxxxxxxxxxxxxxxxxx
> Of course nothing can beat a plain old for loop in terms of readability
and
> -- most likely -- speed.

Here are two versions, meant to be comparable.
Thanks,
Alan Isaac

def cumreduce(func, seq, init = None):
cr = seq[:]
if not(init is None):
if seq:
cr[0] = func(init,seq[0])
else:
cr = [init]
for idx in range(1,len(seq)):
cr[idx] = func(cr[idx-1],seq[idx])
return cr

def ireduce(func, iterable, init=None):
if init is None:
iterable = iter(iterable)
init = iterable.next()
yield init
elif not iterable:
yield init
for item in iterable:
init = func(init, item)
yield init


.

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