On 2012-09-28 16:39, Neal Becker wrote:
I know this should be a fairly basic question, but I'm drawing a blank.
I have code that looks like:
for s0 in xrange (n_syms):
for s1 in xrange (n_syms):
for s2 in xrange (n_syms):
for s3 in xrange (n_syms):
for s4 in range (n_syms):
for s5 in range (n_syms):
Now I need the level of nesting to vary dynamically. (e.g., maybe I need to add
for s6 in range (n_syms))
Smells like a candidate for recursion. Also sounds like a use for yield. Any
suggestions?
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]
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