[EMAIL PROTECTED] wrote:
> Generally, don't create objects, don't perform repeated operations. In
> this case, batch up I/O.
>
>> def write_data1(out, data):
>> for i in data:
>> if i[0] is 'ELEMENT':
>> out.write("%s %06d " % (i[0], i[1]))
>> for j in i[2]:
>> out.write("%d " % (j))
>> out.write("\n")
>
> def write_data1(out, data, map=map, str=str):
> SPACE_JOIN = ' '.join
> lines = [("ELEMENT %06d " % i1) + SPACE_JOIN(map(str, i2))
> for i0, i1, i2 in data if i0 == 'ELEMENT']
> out.write('\n'.join(lines))
>
> While perhaps a bit obfuscated, it's a bit faster than the original.
> Part of what makes this hard to read is the crappy variable names. I
> didn't know what to call them. This version assumes that data will
> always be a sequence of 3-element items.
>
> The original version took about 11.5 seconds, the version above takes
> just over 5 seconds.
footnote: your version doesn't print the final "\n". here's a variant
that do, and leaves the batching to the I/O subsystem:
def write_data3(out, data, map=map, str=str):
SPACE_JOIN = ' '.join
out.writelines(
"ELEMENT %06d %s\n" % (i1, SPACE_JOIN(map(str, i2)))
for i0, i1, i2 in data if i0 == 'ELEMENT'
)
this runs exactly as fast as your example on my machine, but uses less
memory. and if you, for benchmarking purposes, pass in a "sink" file
object that ignores the data you pass it, it runs in no time at all ;-)
</F>
--
http://mail.python.org/mailman/listinfo/python-list
