Getting “global name ‘foo’ is not defined” with Python’s timeit

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Question :

Getting “global name ‘foo’ is not defined” with Python’s timeit

I’m trying to find out how much time it takes to execute a Python statement, so I looked online and found that the standard library provides a module called timeit that purports to do exactly that:

import timeit

def foo():
    # ... contains code I want to time ...

def dotime():
    t = timeit.Timer("foo()")
    time = t.timeit(1)
    print "took %fsn" % (time,)

dotime()

However, this produces an error:

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 3, in dotime
  File "/usr/local/lib/python2.6/timeit.py", line 193, in timeit
    timing = self.inner(it, self.timer)
  File "<timeit-src>", line 6, in inner
NameError: global name 'foo' is not defined

I’m still new to Python and I don’t fully understand all the scoping issues it has, but I don’t know why this snippet doesn’t work. Any thoughts?

Answer #1:

Change this line:

t = timeit.Timer("foo()")

To this:

t = timeit.Timer("foo()", "from __main__ import foo")

Check out the link you provided at the very bottom.

To give the timeit module access to functions you define, you can pass a setup parameter which contains an import statement:

I just tested it on my machine and it worked with the changes.

Answered By: Kyle Cronin

Answer #2:

With Python 3, you can use globals=globals()

t = timeit.Timer("foo()", globals=globals())

From the documentation:

Another option is to pass globals() to the globals parameter, which
will cause the code to be executed within your current global
namespace. This can be more convenient than individually specifying
imports

Answered By: Paolo Bergantino

Answer #3:

You can try this hack:

import timeit

def foo():
    print 'bar'

def dotime():
    t = timeit.Timer("foo()")
    time = t.timeit(1)
    print "took %fsn" % (time,)

import __builtin__
__builtin__.__dict__.update(locals())

dotime()
Answered By: user2314737

Answer #4:

t = timeit.Timer("foo()", "from __main__ import foo")

Since timeit doesn’t have your stuff in scope.

Answered By: Luka Zakrajšek

Answer #5:

add into your setup “import thisfile; “

then when you call the setup function myfunc() use “thisfile.myfunc()”

eg “thisfile.py”

def myfunc():

 return 5

def testable(par):

 pass



t=timeit.timeit(stmt="testable(v)",setup="import thisfile; v=thisfile.myfunc();").repeat(10)

print( t )
Answered By: dwc

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