howto handle nested for
Neil Cerutti
neilc at norwich.edu
Fri Sep 28 16:38:56 EDT 2012
On 2012-09-28, Laszlo Nagy <gandalf at shopzeus.com> wrote:
> In your example, it seem that the iterable of the for loop is
> always the same: range(n_sysms). It seems to be a number. Is
> that true? If that is so, then here is something useful:
>
> import copy
>
> class MultiLevelIterator(object):
> def __init__(self,levels,n):
> assert(levels>0)
> assert(n>0)
> self.levels = levels
> self.values = [0]*levels
> self.n = n
>
> def __iter__(self):
> return self
>
> def next(self):
> res = copy.copy(self.values)
> idx = self.levels-1
> while idx>=0:
> self.values[idx]+=1
> if self.values[idx]>=self.n:
> self.values[idx] = 0
> idx-=1
> else:
> return res
> raise StopIteration
>
> i = MultiLevelIterator(2,3)
> for values in i:
> print values
>
> This will print:
>
> [0, 0]
> [0, 1]
> [0, 2]
> [1, 0]
> [1, 1]
> [1, 2]
> [2, 0]
> [2, 1]
It looks like you might have missed the last one. Also, be sure
to check itertools for occasionally for cool stuff like this.
>>> for values in itertools.product(range(3), repeat=2):
... print(values)
...
(0, 0)
(0, 1)
(0, 2)
(1, 0)
(1, 1)
(1, 2)
(2, 0)
(2, 1)
(2, 2)
--
Neil Cerutti
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