Iteration style

[Abdullah Khaidar]

Is there any iteration style we must use to get faster processing
time? I've tried with some style to concat number in list. But I still
don't know which one is the recommended style.
[color=blue][color=green][color=darkred]
>>> def useListIteratio n():[/color][/color][/color]
list = [str(element) for element in range(5)]
result = ""
for item in list:
result += item
return result
[color=blue][color=green][color=darkred]
>>> def useNormalIterat ion():[/color][/color][/color]
list = [str(element) for element in range(5)]
result = ""
for index in range(len(list) ):
result += list[index]
return result
[color=blue][color=green][color=darkred]
>>> def useJoin():[/color][/color][/color]
list = [str(element) for element in range(5)]
return "".join(lis t)
[color=blue][color=green][color=darkred]
>>> useListIteratio n()[/color][/color][/color]
'01234'[color=blue][color=green][color=darkred]
>>> useNormalIterat ion()[/color][/color][/color]
'01234'[color=blue][color=green][color=darkred]
>>> useJoin()[/color][/color][/color]
'01234'[color=blue][color=green][color=darkred]
>>> def getTimer():[/color][/color][/color]
from timeit import Timer
t1 = Timer("useListI teration", "from __main__ import
useListIteratio n")
t2 = Timer("useNorma lIteration", "from __main__ import
useNormalIterat ion")
t3 = Timer("useJoin" , "from __main__ import useJoin")
print "Using list iteration: ", min(t1.repeat() )
print "Using normal iteration: ", min(t2.repeat() )
print "Using join: " , min(t3.repeat() )

[color=blue][color=green][color=darkred]
>>> getTimer()[/color][/color][/color]
Using list iteration: 0.0700158819068
Using normal iteration: 0.0701589168456
Using join: 0.0685698880724[color=blue][color=green][color=darkred]
>>> getTimer()[/color][/color][/color]
Using list iteration: 0.070928567737
Using normal iteration: 0.0698613929983
Using join: 0.0693454056312[color=blue][color=green][color=darkred]
>>> getTimer()[/color][/color][/color]
Using list iteration: 0.0683511451874
Using normal iteration: 0.0698585993471
Using join: 0.0708022947051[color=blue][color=green][color=darkred]
>>>[/color][/color][/color]

[Michael Hoffman]

Re: Iteration style

Abdullah Khaidar wrote:
[color=blue]
> Is there any iteration style we must use to get faster processing
> time?[/color]

Yes, definitely this one:
[color=blue][color=green][color=darkred]
>>>>def useJoin():[/color][/color]
>
> list = [str(element) for element in range(5)]
> return "".join(lis t)[/color]

You aren't going to get the right results from your getTimer() function
because you are just timing putting the function object on the stack,
rather than actually calling it.
[color=blue][color=green][color=darkred]
>>>>def getTimer():[/color][/color]
>
> from timeit import Timer
> t1 = Timer("useListI teration", "from __main__ import
> useListIteratio n")[/color]

should be t1 = Timer("useListI teration()", "from __main__ import
useListIteratio n")
[color=blue]
> print "Using list iteration: ", min(t1.repeat() )[/color]

Of course now that you are actually calling a function, it should take a
lot longer, so repeating it 3 * 1,000,000 times is way too many. I would
change the number of integers you are concatenating from 5 to 1000 and
run Timer.timeit(nu mber=100) (repeats 3 * 100 times) instead.
[color=blue][color=green][color=darkred]
>>> getTimer()[/color][/color][/color]
Using list iteration: 0.751999855042
Using normal iteration: 0.766999959946
Using join: 0.446000099182

HTH,
--
Michael Hoffman

[Abdullah Khaidar]

Re: Iteration style

Thanks for your correction. Now I've found that using join (list
methods) is better than others.

--M.Abdullah Khaidar

http://khaidarmak.blogspot.com

Michael Hoffman <m.h.3.9.1.with out.dots.at.cam .ac.uk@example. com> wrote in message news:<ciubec$ob q$1@pegasus.csx .cam.ac.uk>...[color=blue]
> Abdullah Khaidar wrote:
>[color=green]
> > Is there any iteration style we must use to get faster processing
> > time?[/color]
>
> Yes, definitely this one:
>[color=green][color=darkred]
> >>>>def useJoin():[/color]
> >
> > list = [str(element) for element in range(5)]
> > return "".join(lis t)[/color]
>
> You aren't going to get the right results from your getTimer() function
> because you are just timing putting the function object on the stack,
> rather than actually calling it.
>[color=green][color=darkred]
> >>>>def getTimer():[/color]
> >
> > from timeit import Timer
> > t1 = Timer("useListI teration", "from __main__ import
> > useListIteratio n")[/color]
>
> should be t1 = Timer("useListI teration()", "from __main__ import
> useListIteratio n")
>[color=green]
> > print "Using list iteration: ", min(t1.repeat() )[/color]
>
> Of course now that you are actually calling a function, it should take a
> lot longer, so repeating it 3 * 1,000,000 times is way too many. I would
> change the number of integers you are concatenating from 5 to 1000 and
> run Timer.timeit(nu mber=100) (repeats 3 * 100 times) instead.
>[color=green][color=darkred]
> >>> getTimer()[/color][/color]
> Using list iteration: 0.751999855042
> Using normal iteration: 0.766999959946
> Using join: 0.446000099182
>
> HTH,[/color]