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 %fs\n" % (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?
%%timeit. You can use the magic command %%timeit to measure the execution time of the cell. As an example, try executing the same process using NumPy . As with %timeit , -n and -r are optional.
The “%timeit” is a line magic command in which the code consists of a single line or should be written in the same line for measuring the execution time. In the “%timeit” command, the particular code is specified after the “%timeit” is separated by a space.
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.
With Python 3, you can use globals=globals()
t = timeit.Timer("foo()", globals=globals())
From the documentation:
Another option is to pass
globals()
to theglobals
parameter, which will cause the code to be executed within your current global namespace. This can be more convenient than individually specifying imports
You can try this hack:
import timeit
def foo():
print 'bar'
def dotime():
t = timeit.Timer("foo()")
time = t.timeit(1)
print "took %fs\n" % (time,)
import __builtin__
__builtin__.__dict__.update(locals())
dotime()
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