Chris wrote:
> So my question is how can I speed up what's happening inside the
> function write_data()? Only allowed to use vanilla python (no psycho or
> other libraries outside of a vanilla python install).
> 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")
# reference, modified to avoid trailing ' '
def write_data(out, data):
for i in data:
if i[0] == 'ELEMENT':
out.write("%s %06d" % (i[0], i[1]))
for j in i[2]:
out.write(" %d" % j)
out.write("\n")
# Norvitz/Lundh
def writelines_data(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'
)
def print_data(out, data):
for name, index, items in data:
if name == "ELEMENT":
print >> out, "ELEMENT %06d" % index,
for item in items:
print >> out, item,
print >> out
import time
data = []
for i in range(500000):
data.append(("ELEMENT", i, (1,2,3,4,5,6)))
for index, write in enumerate([write_data, writelines_data, print_data]):
fname = "test%s.txt" % index
out = open(fname,'w')
start = time.time()
write(out, data)
out.close()
print write.__name__, time.time()-start
for fname in "test1.txt", "test2.txt":
assert open(fname).read() == open("test0.txt").read(), fname
Output on my machine:
$ python2.5 writedata.py
write_data 10.3382301331
writelines_data 5.4960360527
print_data 3.50765490532
Moral: don't forget about good old print. It does have an opcode(*) of its
own, after all.
Peter
(*) or two
--
http://mail.python.org/mailman/listinfo/python-list
