Comments on: Steven Caron, OBJ Files, Sexy Bits and Waste

By: Andy Nicholas

Andy Nicholas — Sun, 23 Mar 2008 11:52:46 +0000

Very interesting link that (for nerds like me anyway). Thanks :-)

By: Patrick Boucher

Patrick Boucher — Mon, 17 Mar 2008 13:46:18 +0000

Stumbled onto this article describing Python optimization this morning.
Thought it was appropriate.

http://www.python.org/doc/essays/list2str.html

By: Ciaran Moloney

Ciaran Moloney — Sat, 08 Mar 2008 23:56:16 +0000

Thanks, folks!
As a novice scripter, I found this all to be very informative.

By: Bernard Lebel

Bernard Lebel — Wed, 05 Mar 2008 16:41:16 +0000

Me again,

I reworked the function a little bit. In bernardFloat(), I change the not … >= to a simple <.
I also added bernardFloat2(), which does the same thing except creating a temp variable.

def bernardFloat(version):
    fVersion = float( version[:3] )
    if fVersion < 6.5:
        pass
 
def bernardFloat2(version):
    if float(version[:3]) < 6.5:
        pass

New results:

Testing with version string '6.0'
----- o -----
steven          0.359300041199
patrick         0.36099998951
andy            0.378199982643
andyNoTempVar   0.454500007629
bernard         0.490700006485
bernardList     0.468799996376
bernardFloat    0.212400007248
bernardFloat2   0.209499979019

Testing with version string '6.5'
----- o -----
steven          0.361100029945
patrick         0.359200000763
andy            0.378199982643
andyNoTempVar   0.459399986267
bernard         0.525099992752
bernardList     0.467100024223
bernardFloat    0.25
bernardFloat2   0.245299983025

Testing with version string '7.0'
----- o -----
steven          0.362500047684
patrick         0.360899996758
andy            0.365499973297
andyNoTempVar   0.363999962807
bernard         0.489200019836
bernardList     0.453099989891
bernardFloat    0.214200091362
bernardFloat2   0.207699918747

So skipping the temp variable is even faster!

By: Bernard Lebel

Bernard Lebel — Wed, 05 Mar 2008 16:29:25 +0000

Hey guys, check this out.

I thought that all we were interested in is the version to be 6.5 or more. That’s it. The number of digits after the decimal doesn’t matter.

So I thought that I could simply take the 3 first characters, convert them to float, and test against that. If the XSI version is ever going to be above 9, it doesn’t matter, because at 10 we know for sure we’re beyond 6.5.

So wrote this function. No split, no join, no round, no conversion to int, only one comparison.

def bernardFloat(version):
    fVersion = float( version[:3] )
    if not fVersion >= 6.5:
        pass

(let me know if I’ve overlooked something!)

And then I ran Patrick’s test code (although I only did 1,000,000 iterations, as my computer is slower than his). My results:

Testing with version string '6.0'
----- o -----
steven          0.359000039101
patrick         0.35649998188
andy            0.375
andyNoTempVar   0.453299975395
bernard         0.487199997902
bernardList     0.462599992752
bernardFloat    0.214199995995

Testing with version string '6.5'
----- o -----
patrick         0.357999968529
steven          0.356000041962
andy            0.364100003242
andyNoTempVar   0.359200000763
bernard         0.484500002861
bernardList     0.453199982643
bernardFloat    0.21400001049

Testing with version string '7.0'
----- o -----
steven          0.354699969292
patrick         0.357800030708
andy            0.373399996758
andyNoTempVar   0.453199982643
bernard         0.521800017357
bernardList     0.465700006485
bernardFloat    0.25

You’ll also notice this entry: bernardList. I wanted to see how things go if I converted the number to integers via a list comprehension:

def bernardList(version):
    aVersion = [int(sNumber) for sNumber in version.split('.')]
    if (aVersion[0] < 6) or (aVersion[0] == 6 and aVersion[1] < 5):
        pass

I love this stuff!

Bernard

By: Steven Caron

Steven Caron — Mon, 03 Mar 2008 22:19:01 +0000

sweet… i was feeling all dumb about my if/else if setup and it runs with acceptable speed.

i do find bernard’s harder to read and i dont think i would opt for his code because code maintenance is often shared (your comments go a long way and make up for it) between developers and when i leave the code for a few months and come back i dont want to be scratching my head because i didn’t comment :)

fun stuff! true purpose of xsiblog!

By: Andy Nicholas

Andy Nicholas — Mon, 03 Mar 2008 21:36:33 +0000

I have to say that I like Bernards method for the elegance of the procedure. I think it is a little harder to read and understand at first glance, but that’s why he’s been good enough to put nice big comments there :-D

Thanks for doing the testing Patrick.

By: Patrick Boucher

Patrick Boucher — Mon, 03 Mar 2008 18:07:06 +0000

Oops.

The andyNoTempVar function should have read:

def andyNoTempVar(version):
    tXSIVersion = version.split('.')
    if int(tXSIVersion[0]) < 6 or (int(tXSIVersion[0]) == 6 and int(tXSIVersion[1]) < 5):
        pass

I’d forgotten the explicit int conversions. It winds up being slower than the temp variable version in function andy. So, the temp var version, for having one less conversion creeps ahead in the standings of two tests. New numbers, again with ten million runs:

Testing with version string '6.0'
---------- o -----------
       steven 1.6405577898
      patrick 1.68582975864
         andy 1.7813429594
andyNoTempVar 2.06077568531
      bernard 2.4824331522

Testing with version string '7.0'
---------- o -----------
       steven 1.62016811371
      patrick 1.56284923553
         andy 1.61941108704
andyNoTempVar 1.53076636791
      bernard 2.48117063046

Testing with version string '6.5'
---------- o -----------
       steven 1.61195776463
      patrick 1.66966564655
         andy 1.77969810963
andyNoTempVar 2.00582532883
      bernard 2.63731787205

By: Bernard Lebel

Bernard Lebel — Mon, 03 Mar 2008 17:35:20 +0000

Nice! Thanks a lot for this!

By: Patrick Boucher

Patrick Boucher — Mon, 03 Mar 2008 16:37:27 +0000

This is what I used to test. If anyone finds problems with this, please point them out.
Yes, I’m timing a range loop, a function call and variable passing but they are the same in all tests so they kind of cancel out. The time differences we notice are due to the contents of the various functions.

import time
avgIter = 10
iter = 1000000
 
def timeit(version, funcs):
    results = dict(zip([f.__name__ for f in funcs], [0.0] * len(funcs)))
 
    for avgi in range(avgIter):
        for func in funcs:
            start = time.time()
            for i in range(iter):
                func(version)
            duration = time.time() - start
            results[func.__name__] += duration
            print '%s - %s: %f' % (func.__name__, version, duration)
    print '----- o -----'
    for k, v in results.iteritems():
        print k, v/avgIter
 
def steven(version):
    tXSIVersion = version.split('.')
    if int( tXSIVersion[0] ) < 6:
        pass
    else:
        if int( tXSIVersion[1] ) < 5:
            pass
 
def patrick(version):
    tXSIVersion = version.split('.')
    if int( tXSIVersion[0] ) < 6 or int( tXSIVersion[1] ) < 5:
        pass
 
def andy(version):
    tXSIVersion = version.split('.')
    majorver = int( tXSIVersion[0] )
    minorver = int( tXSIVersion[1] )
    if majorver < 6 or (majorver == 6 and minorver < 5):
        pass
 
def andyNoTempVar(version):
    tXSIVersion = version.split('.')
    if tXSIVersion[0] < 6 or (tXSIVersion[0] == 6 and tXSIVersion[1] < 5):
        pass
 
def bernard(version):
    # Form version number that includes only the major and minor version numbers
    sVersion = '.'.join( version.split('.')[0:2] )
    # Convert this number to float, round it to 2 digits to be sure
    fVersion = round( float(sVersion), 2 )
 
    if not fVersion >= 6.5:
        pass
 
if __name__ == '__main__':
    funcs = [steven, patrick, andy, andyNoTempVar, bernard]
    for v in ['6.0', '7.0', '6.5']:
        timeit(v, funcs)