cStringIO rules (was Re: O(n^2) is bad - can it be fixed?)

[Alex Martelli]

"Chris Tavares" <ctavares at develop.com> wrote in message
news:aVnO6.8300$9D5.805877 at newsread2.prod.itd.earthlink.net...
    ...
> Another solution would be to use something that IS expected to act like a
> buffer - the cStringIO module. The interface is a little different - this
> one works like a file:

Good point!  So I added it to my little measurement script:

def AppendTest(listorarray):
    head = repr(listorarray)
    start = time.clock()
    for i in range(0, 100):
        for x in range(0, 2000):
            listorarray.append(' ')
        # print i
    stend = time.clock()
    print "%s: %.2f" % (head, stend-start)

def AppendTest1(listorarray):
    head = repr(listorarray)
    start = time.clock()
    for i in range(0, 100):
        for x in range(0, 2000):
            listorarray.write(' ')
        # print i
    stend = time.clock()
    print "%s: %.2f" % (head, stend-start)

AppendTest([])
AppendTest(array.array('c'))
AppendTest1(cStringIO.StringIO())

and, whaddyaknow...:

D:\py21>python oaat.py
[]: 1.96
array('c'): 1.57
<StringO object at 007F63B0>: 0.86

D:\py21>python oaat.py
[]: 1.96
array('c'): 1.57
<StringO object at 007F63B0>: 0.87

D:\py21>

Bingo, another "almost a factor of 2" speedup.

Interesting!-)  Guido's optimization anecdote
may need updating:-).


Alex