NameError for using timeit in python

Question

I got NameError when I try to run this codes."global name j is not defined". How can I fix it?

def test(j):
    for i in range(j):
        j = i**2

if __name__=='__main__':
    from timeit import Timer
    j = 30
    t = Timer("test(j)","from __main__ import test")
    print( t.timeit(j))

from __main__ import test, j works and you have too many j s — msw
– msw, Commented Jul 26, 2010 at 8:40

Andrew Jaffe · Accepted Answer · 2010-07-26 10:40:12Z

3

Timer doesn't know about j. You need to do something like "test(%d)" % j (or from __main__ import j or put the definition of j inside the string, too).

Also, the argument to timeit is different from the argument to your test function (so the different uses of j are probably not what you should do or mean). The timeit argument gives the number of executions for the test function.

p.s. Note that you need to indent any code in your question to get it formatted

p.p.s. There used to be a comment here about not using from __main__ import but that actually does work!

edited Jul 26, 2010 at 10:40

answered Jul 26, 2010 at 8:34

Andrew Jaffe

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1 Comment

msw Over a year ago

from __main__ import test works, try it. Is it preferred? Dunno, but would welcome an explanation why not.

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