diff -r c59378c8007b Lib/timeit.py --- a/Lib/timeit.py Wed May 11 13:01:42 2016 +1000 +++ b/Lib/timeit.py Thu May 12 00:58:29 2016 +1000 @@ -207,6 +207,26 @@ 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 @@ 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: