Re: [Tutor] timeit at the command line
Dick Moores wrote: I DID have setup code, the x=0. I now notice that if the x=0 is not stated as the setup code, the time difference is enormous, 132-to-1 in this case. python -m timeit -sx=0 while x100: x+=1 1000 loops, best of 3: 0.116 usec per loop python -m timeit x=0 while x100: x+=1 10 loops, best of 3: 15.3 usec per loop timeit runs the setup code once, then runs the timed code many times with the timer running. If x=0 is outside the loop, then the while loop only runs once, because x == 100 after the first time through the loop. So your first version is effectively timing this: setup: x=100 timed code: while x100: x+=1 which is of course a lot faster than actually running the loopp 100 times. Kent ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] timeit at the command line
At 03:05 AM 10/3/2006, Kent Johnson wrote: Dick Moores wrote: I DID have setup code, the x=0. I now notice that if the x=0 is not stated as the setup code, the time difference is enormous, 132-to-1 in this case. python -m timeit -sx=0 while x100: x+=1 1000 loops, best of 3: 0.116 usec per loop python -m timeit x=0 while x100: x+=1 10 loops, best of 3: 15.3 usec per loop timeit runs the setup code once, then runs the timed code many times with the timer running. If x=0 is outside the loop, then the while loop only runs once, because x == 100 after the first time through the loop. So your first version is effectively timing this: setup: x=100 timed code: while x100: x+=1 which is of course a lot faster than actually running the loopp 100 times. Thanks, Kent. I was beginning to understand this, and now you've nailed it down for me. Dick ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] timeit at the command line
Dick Moores wrote: At 03:05 AM 10/3/2006, Kent Johnson wrote: timeit runs the setup code once, then runs the timed code many times with the timer running. If x=0 is outside the loop, then the while loop only runs once, because x == 100 after the first time through the loop. So your first version is effectively timing this: setup: x=100 timed code: while x100: x+=1 which is of course a lot faster than actually running the loopp 100 times. Thanks, Kent. I was beginning to understand this, and now you've nailed it down for me. You might want to look at the source, timeit.py. There is a code template (called 'template') near the beginning. Your setup and timed code are inserted into the template, then it is compiled and run. One of the dangers of timeit is that you may time something different than what you think you are timing, as you did. It's an easy mistake to make and hard to protect against. Kent ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] timeit at the command line
At 04:35 AM 10/3/2006, Kent Johnson wrote: Dick Moores wrote: At 03:05 AM 10/3/2006, Kent Johnson wrote: timeit runs the setup code once, then runs the timed code many times with the timer running. If x=0 is outside the loop, then the while loop only runs once, because x == 100 after the first time through the loop. So your first version is effectively timing this: setup: x=100 timed code: while x100: x+=1 which is of course a lot faster than actually running the loopp 100 times. Thanks, Kent. I was beginning to understand this, and now you've nailed it down for me. You might want to look at the source, timeit.py. There is a code template (called 'template') near the beginning. Your setup and timed code are inserted into the template, then it is compiled and run. Very interesting. I thought a line of that template looked familiar. I was seeing _t0 = _timer() regularly when I had the -s option set without any setup: C:\python -m timeit -r 3 -sfor x in range(1): x*x Traceback (most recent call last): File E:\Python25\lib\runpy.py, line 95, in run_module filename, loader, alter_sys) File E:\Python25\lib\runpy.py, line 52, in _run_module_co mod_name, mod_fname, mod_loader) File E:\Python25\lib\runpy.py, line 32, in _run_code exec code in run_globals File E:\Python25\lib\timeit.py, line 285, in module sys.exit(main()) File E:\Python25\lib\timeit.py, line 249, in main t = Timer(stmt, setup, timer) File E:\Python25\lib\timeit.py, line 116, in __init__ code = compile(src, dummy_src_name, exec) File timeit-src, line 4 _t0 = _timer() ^ But I don't understand what the error has to do with _t0 . That's OK, don't bother to explain. I don't understand classes yet anyway. Should get into them soon, with Wes Chun's book. One of the dangers of timeit is that you may time something different than what you think you are timing, as you did. It's an easy mistake to make and hard to protect against. Yes. thanks, Kent. Dick Kent ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] timeit at the command line
Dick Moores wrote: Very interesting. I thought a line of that template looked familiar. I was seeing _t0 = _timer() regularly when I had the -s option set without any setup: C:\python -m timeit -r 3 -sfor x in range(1): x*x Traceback (most recent call last): File E:\Python25\lib\runpy.py, line 95, in run_module filename, loader, alter_sys) File E:\Python25\lib\runpy.py, line 52, in _run_module_co mod_name, mod_fname, mod_loader) File E:\Python25\lib\runpy.py, line 32, in _run_code exec code in run_globals File E:\Python25\lib\timeit.py, line 285, in module sys.exit(main()) File E:\Python25\lib\timeit.py, line 249, in main t = Timer(stmt, setup, timer) File E:\Python25\lib\timeit.py, line 116, in __init__ code = compile(src, dummy_src_name, exec) File timeit-src, line 4 _t0 = _timer() ^ But I don't understand what the error has to do with _t0 . That's OK, don't bother to explain. I don't understand classes yet anyway. Should get into them soon, with Wes Chun's book. If you substitute your code into the template by hand and look at the actual exception (not shown above) you should see the problem. It doesn't have anything to do with classes. Kent Kent ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] timeit at the command line
At 05:54 AM 10/3/2006, Kent Johnson wrote:
Dick Moores wrote:
Very interesting. I thought a line of that template looked
familiar. I was seeing _t0 = _timer() regularly when I had the -s
option set without any setup:
C:\python -m timeit -r 3 -sfor x in range(1): x*x
Traceback (most recent call last):
File E:\Python25\lib\runpy.py, line 95, in run_module
filename, loader, alter_sys)
File E:\Python25\lib\runpy.py, line 52, in _run_module_co
mod_name, mod_fname, mod_loader)
File E:\Python25\lib\runpy.py, line 32, in _run_code
exec code in run_globals
File E:\Python25\lib\timeit.py, line 285, in module
sys.exit(main())
File E:\Python25\lib\timeit.py, line 249, in main
t = Timer(stmt, setup, timer)
File E:\Python25\lib\timeit.py, line 116, in __init__
code = compile(src, dummy_src_name, exec)
File timeit-src, line 4
_t0 = _timer()
^
But I don't understand what the error has to do with _t0 . That's
OK, don't bother to explain. I don't understand classes yet anyway.
Should get into them soon, with Wes Chun's book.
If you substitute your code into the template by hand and look at
the actual exception (not shown above) you should see the problem.
It doesn't have anything to do with classes.
I meant timeit.py has classes.
OK, I called timeit.py with this template:
template =
def inner(_it, _timer):
%(setup)s
_t0 = _timer()
for _i in _it:
%(x=0 while x100: x*x)s
_t1 = _timer()
return _t1 - _t0
And got this error:
E:\Python25\Scripts-NotMinetimeit.py
Traceback (most recent call last):
File E:\Python25\Scripts-NotMine\timeit.py, li
sys.exit(main())
File E:\Python25\Scripts-NotMine\timeit.py, li
t = Timer(stmt, setup, timer)
File E:\Python25\Scripts-NotMine\timeit.py, li
src = template % {'stmt': stmt, 'setup': setup
KeyError: 'x=0 while x100: x*x'
So what's the error? I've probably misunderstood how to do the substitution..
Dick
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Re: [Tutor] timeit at the command line
Dick Moores wrote: At 05:54 AM 10/3/2006, Kent Johnson wrote: Dick Moores wrote: Very interesting. I thought a line of that template looked familiar. I was seeing _t0 = _timer() regularly when I had the -s option set without any setup: C:\python -m timeit -r 3 -sfor x in range(1): x*x Traceback (most recent call last): File E:\Python25\lib\runpy.py, line 95, in run_module filename, loader, alter_sys) File E:\Python25\lib\runpy.py, line 52, in _run_module_co mod_name, mod_fname, mod_loader) File E:\Python25\lib\runpy.py, line 32, in _run_code exec code in run_globals File E:\Python25\lib\timeit.py, line 285, in module sys.exit(main()) File E:\Python25\lib\timeit.py, line 249, in main t = Timer(stmt, setup, timer) File E:\Python25\lib\timeit.py, line 116, in __init__ code = compile(src, dummy_src_name, exec) File timeit-src, line 4 _t0 = _timer() ^ But I don't understand what the error has to do with _t0 . That's OK, don't bother to explain. I don't understand classes yet anyway. Should get into them soon, with Wes Chun's book. If you substitute your code into the template by hand and look at the actual exception (not shown above) you should see the problem. It doesn't have anything to do with classes. I meant timeit.py has classes. OK, I called timeit.py with this template: template = def inner(_it, _timer): %(setup)s _t0 = _timer() for _i in _it: %(x=0 while x100: x*x)s _t1 = _timer() return _t1 - _t0 OK, let's go back to your first example and I will explain in more detail. timeit.py contains this template: template = def inner(_it, _timer): %(setup)s _t0 = _timer() for _i in _it: %(stmt)s _t1 = _timer() return _t1 - _t0 Whatever you specify for setup code is substituted for %(setup)s; the timed statement is substituted for %(stmt)s. This is done using standard string formatting operations. The result of the substitutions is a function definition which is compiled and run. So if you run python -m timeit -sfor x in range(1): x*x the generated function looks like this: def inner(_it, _timer): for x in range(1): _t0 = _timer() for _i in _it: x*x _t1 = _timer() return _t1 - _t0 The for statement should begin an indented block; the next statement is *not* indented, so you get an IndentationError. Does that help? Kent ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] timeit at the command line
At 07:08 AM 10/3/2006, Kent Johnson wrote: Dick Moores wrote: At 05:54 AM 10/3/2006, Kent Johnson wrote: Dick Moores wrote: Very interesting. I thought a line of that template looked familiar. I was seeing _t0 = _timer() regularly when I had the -s option set without any setup: C:\python -m timeit -r 3 -sfor x in range(1): x*x Traceback (most recent call last): File E:\Python25\lib\runpy.py, line 95, in run_module filename, loader, alter_sys) File E:\Python25\lib\runpy.py, line 52, in _run_module_co mod_name, mod_fname, mod_loader) File E:\Python25\lib\runpy.py, line 32, in _run_code exec code in run_globals File E:\Python25\lib\timeit.py, line 285, in module sys.exit(main()) File E:\Python25\lib\timeit.py, line 249, in main t = Timer(stmt, setup, timer) File E:\Python25\lib\timeit.py, line 116, in __init__ code = compile(src, dummy_src_name, exec) File timeit-src, line 4 _t0 = _timer() ^ But I don't understand what the error has to do with _t0 . That's OK, don't bother to explain. I don't understand classes yet anyway. Should get into them soon, with Wes Chun's book. If you substitute your code into the template by hand and look at the actual exception (not shown above) you should see the problem. It doesn't have anything to do with classes. I meant timeit.py has classes. OK, I called timeit.py with this template: template = def inner(_it, _timer): %(setup)s _t0 = _timer() for _i in _it: %(x=0 while x100: x*x)s _t1 = _timer() return _t1 - _t0 OK, let's go back to your first example and I will explain in more detail. Sorry to be so dumb. timeit.py contains this template: template = def inner(_it, _timer): %(setup)s _t0 = _timer() for _i in _it: %(stmt)s _t1 = _timer() return _t1 - _t0 Whatever you specify for setup code is substituted for %(setup)s; the timed statement is substituted for %(stmt)s. This is done using standard string formatting operations. The result of the substitutions is a function definition which is compiled and run. So if you run python -m timeit -sfor x in range(1): x*x the generated function looks like this: def inner(_it, _timer): for x in range(1): _t0 = _timer() for _i in _it: x*x _t1 = _timer() return _t1 - _t0 The for statement should begin an indented block; the next statement is *not* indented, so you get an IndentationError. Yes, that's exactly what I got when using timeit with that code at the command line, which I didn't understand. John Fouhy explained it. Does that help? Yes, you've shown me a couple of things. How to substitute in a template. How it can be useful to look at the code of modules. And in this case I'll be able to use that template in a copy of timeit.py without going to the command line, with which I usually struggle. Thanks again, again. Dick Kent ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] timeit at the command line
Dick Moores wrote: C:\python -m timeit -sx=0 while x100: x+=1 1000 loops, best of 3: 0.123 usec per loop C:\python -m timeit -sfor x in range(100): x+=1 Traceback (most recent call last): File E:\Python25\lib\runpy.py, line 95, in run_module filename, loader, alter_sys) File E:\Python25\lib\runpy.py, line 52, in _run_module_code mod_name, mod_fname, mod_loader) File E:\Python25\lib\runpy.py, line 32, in _run_code exec code in run_globals File E:\Python25\lib\timeit.py, line 285, in module sys.exit(main()) File E:\Python25\lib\timeit.py, line 249, in main t = Timer(stmt, setup, timer) File E:\Python25\lib\timeit.py, line 116, in __init__ code = compile(src, dummy_src_name, exec) File timeit-src, line 4 _t0 = _timer() ^ IndentationError: expected an indented block Is there a better way to indicate the indentation of x+=1 (2 spaces in this case) ? For me, this usually works in a while loop, but so far, never in a for loop. Strange, your example works for me in Python 2.4 and 2.5: D:\python -m timeit -sx=0 while x100: x+=1 1000 loops, best of 3: 0.102 usec per loop Are you using 2.5 final or one of the earlier releases? Kent ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] timeit at the command line
At 03:08 AM 10/2/2006, Kent Johnson wrote: Dick Moores wrote: C:\python -m timeit -sx=0 while x100: x+=1 1000 loops, best of 3: 0.123 usec per loop C:\python -m timeit -sfor x in range(100): x+=1 Traceback (most recent call last): File E:\Python25\lib\runpy.py, line 95, in run_module filename, loader, alter_sys) File E:\Python25\lib\runpy.py, line 52, in _run_module_code mod_name, mod_fname, mod_loader) File E:\Python25\lib\runpy.py, line 32, in _run_code exec code in run_globals File E:\Python25\lib\timeit.py, line 285, in module sys.exit(main()) File E:\Python25\lib\timeit.py, line 249, in main t = Timer(stmt, setup, timer) File E:\Python25\lib\timeit.py, line 116, in __init__ code = compile(src, dummy_src_name, exec) File timeit-src, line 4 _t0 = _timer() ^ IndentationError: expected an indented block Is there a better way to indicate the indentation of x+=1 (2 spaces in this case) ? For me, this usually works in a while loop, but so far, never in a for loop. Strange, your example works for me in Python 2.4 and 2.5: D:\python -m timeit -sx=0 while x100: x+=1 1000 loops, best of 3: 0.102 usec per loop Are you using 2.5 final or one of the earlier releases? 2.5 final. Dick ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] timeit at the command line
At 01:50 PM 10/2/2006, John Fouhy wrote: On 02/10/06, Dick Moores [EMAIL PROTECTED] wrote: C:\python -m timeit -sfor x in range(100): x+=1 Traceback (most recent call last): The -s option specifies the setup code. In this case, you don't have any setup code. Try this: python -m timeit for x in range(100): x += 1 HTH! -- John. Terrific! E:\Python25\devpython -m timeit for x in range(100): x += 1 10 loops, best of 3: 14.9 usec per loop So with python -m timeit -sx=0 while x100: x+=1 1000 loops, best of 3: 0.123 usec per loop I DID have setup code, the x=0. I now notice that if the x=0 is not stated as the setup code, the time difference is enormous, 132-to-1 in this case. python -m timeit -sx=0 while x100: x+=1 1000 loops, best of 3: 0.116 usec per loop python -m timeit x=0 while x100: x+=1 10 loops, best of 3: 15.3 usec per loop Thanks, John. Dick ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
