On 10/20/2011 9:23 AM, Yingjie Lan wrote:
it seems a generator expression can be used only once:
Generators are iterators. Once iterators raise StopIteration, they are
supposed to continue doing so.
A generator expression defines a temporary anonymous generator function
that is called once to produce a generator and then deleted. It, like
all comprehensions, is purely a convenient abbreviation.
g = (x*x for x in range(3))
for x in g: print x
0 1 4
for x in g: print x #nothing printed
Define a named generator function (and add a parameter to make it more
flexible and useful and reuse it.
def g(n):
for i in range(n):
yield i*i
Then, "for x in g(3)", "for x in g(8)", "for x in g(y*x)", etc, as many
times as you want. You might call it 'square' or even 'r_square' instead
of 'g'.
--
Terry Jan Reedy
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