frange() question
George Trojan
george.trojan at noaa.gov
Thu Sep 20 09:08:17 EDT 2007
A while ago I found somewhere the following implementation of frange():
def frange(limit1, limit2 = None, increment = 1.):
"""
Range function that accepts floats (and integers).
Usage:
frange(-2, 2, 0.1)
frange(10)
frange(10, increment = 0.5)
The returned value is an iterator. Use list(frange) for a list.
"""
if limit2 is None:
limit2, limit1 = limit1, 0.
else:
limit1 = float(limit1)
count = int(math.ceil(limit2 - limit1)/increment)
return (limit1 + n*increment for n in range(count))
I am puzzled by the parentheses in the last line. Somehow they make
frange to be a generator:
>> print type(frange(1.0, increment=0.5))
<type 'generator'>
But I always thought that generators need a keyword "yield". What is
going on here?
George
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