Issue6422 add autorange method to timeit.Timer

This commit is contained in:
Steven D'Aprano 2016-08-15 01:27:03 +10:00
parent 9171a8b4ce
commit 09f4f711b6
3 changed files with 69 additions and 13 deletions

View File

@ -100,8 +100,8 @@ The module defines three convenience functions and a public class:
can be controlled by passing a namespace to *globals*.
To measure the execution time of the first statement, use the :meth:`.timeit`
method. The :meth:`.repeat` method is a convenience to call :meth:`.timeit`
multiple times and return a list of results.
method. The :meth:`.repeat` and :meth:`.autorange` methods are convenience
methods to call :meth:`.timeit` multiple times.
The execution time of *setup* is excluded from the overall timed execution run.
@ -134,6 +134,21 @@ The module defines three convenience functions and a public class:
timeit.Timer('for i in range(10): oct(i)', 'gc.enable()').timeit()
.. method:: Timer.autorange(callback=None)
Automatically determine how many times to call :meth:`.timeit`.
This is a convenience function that calls :meth:`.timeit` repeatedly
so that the total time >= 0.2 second, returning the eventual
(number of loops, time taken for that number of loops). It calls
:meth:`.timeit` with *number* set to successive powers of ten (10,
100, 1000, ...) up to a maximum of one billion, until the time taken
is at least 0.2 second, or the maximum is reached.
If *callback* is given and is not *None*, it will be called after
each trial with two arguments: ``callback(number, time_taken)``.
.. method:: Timer.repeat(repeat=3, number=1000000)
Call :meth:`.timeit` a few times.

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@ -354,6 +354,28 @@ class TestTimeit(unittest.TestCase):
s = self.run_main(switches=['-n1', '1/0'])
self.assert_exc_string(error_stringio.getvalue(), 'ZeroDivisionError')
def autorange(self, callback=None):
timer = FakeTimer(seconds_per_increment=0.001)
t = timeit.Timer(stmt=self.fake_stmt, setup=self.fake_setup, timer=timer)
return t.autorange(callback)
def test_autorange(self):
num_loops, time_taken = self.autorange()
self.assertEqual(num_loops, 1000)
self.assertEqual(time_taken, 1.0)
def test_autorange_with_callback(self):
def callback(a, b):
print("{} {:.3f}".format(a, b))
with captured_stdout() as s:
num_loops, time_taken = self.autorange(callback)
self.assertEqual(num_loops, 1000)
self.assertEqual(time_taken, 1.0)
expected = ('10 0.010\n'
'100 0.100\n'
'1000 1.000\n')
self.assertEqual(s.getvalue(), expected)
if __name__ == '__main__':
unittest.main()

View File

@ -207,6 +207,26 @@ class Timer:
r.append(t)
return r
def autorange(self, callback=None):
"""Return the number of loops so that total time >= 0.2.
Calls the timeit method with *number* set to successive powers of
ten (10, 100, 1000, ...) up to a maximum of one billion, until
the time taken is at least 0.2 second, or the maximum is reached.
Returns ``(number, time_taken)``.
If *callback* is given and is not None, it will be called after
each trial with two arguments: ``callback(number, time_taken)``.
"""
for i in range(1, 10):
number = 10**i
time_taken = self.timeit(number)
if callback:
callback(number, time_taken)
if time_taken >= 0.2:
break
return (number, time_taken)
def timeit(stmt="pass", setup="pass", timer=default_timer,
number=default_number, globals=None):
"""Convenience function to create Timer object and call timeit method."""
@ -295,17 +315,16 @@ def main(args=None, *, _wrap_timer=None):
t = Timer(stmt, setup, timer)
if number == 0:
# determine number so that 0.2 <= total time < 2.0
for i in range(1, 10):
number = 10**i
try:
x = t.timeit(number)
except:
t.print_exc()
return 1
if verbose:
print("%d loops -> %.*g secs" % (number, precision, x))
if x >= 0.2:
break
callback = None
if verbose:
def callback(number, time_taken):
msg = "{num} loops -> {secs:.{prec}g} secs"
print(msg.format(num=number, secs=time_taken, prec=precision))
try:
number, _ = t.autorange(callback)
except:
t.print_exc()
return 1
try:
r = t.repeat(repeat, number)
except: