Dave Angel wrote:
norseman wrote:
div class=moz-text-flowed style=font-family: -moz-fixedMarco
Mariani wrote:
Gediminas Kregzde wrote:
def doit(i):
pass
def main():
a = [0] * 1000
t = time()
map(doit, a)
print map time: + str(time() - t)
Here you are calling a
Hello,
I'm Vilnius college II degree student and last semester our teacher
introduced us to python
I've used to program with Delphi, so I very fast adopted to python
Now I'm developing cross platform program and use huge amounts of
data. Program is needed to run as fast as it coud. I've read all
Gediminas Kregzde:
map function is slower than
for loop for about 5 times, when using huge amounts of data.
It is needed to perform some operations, not to return data.
Then you are using map() for the wrong purpose. map() purpose is to
build a list of things. Use a for loop.
Bye,
bearophile
and this, while it's realy doing something is even 4 times faster than
main2 ;-)
And if you only need integers, it can be even faster.
def main3():
from numpy import zeros
t = time()
a = zeros ( 1000 )
b = a + 3.14
print loop time: + str(time() - t)
cheers,
Stef
Gediminas
Gediminas Kregzde wrote:
def doit(i):
pass
def main():
a = [0] * 1000
t = time()
map(doit, a)
print map time: + str(time() - t)
Here you are calling a function ten million times, build a list with of
ten million None results, then throw it away.
def main2():
t =
map is creating a new list of 10,000,000 items, not modifying the
values inside list a. That's probably where your time difference comes
from...
Jaime
On Fri, May 15, 2009 at 1:56 PM, Gediminas Kregzde
gediminas.kreg...@gmail.com wrote:
Hello,
I'm Vilnius college II degree student and last
Gediminas Kregzde wrote:
Now I'm developing cross platform program and use huge amounts of
data. Program is needed to run as fast as it coud. I've read all tips
about geting performance, but got 1 bug: map function is slower than
for loop for about 5 times, when using huge amounts of data.
(1) building another throwaway list and
(2) function call overhead for calling doit()
You can avoid (1) by using filter() instead of map()
Are you sure of this? My python returns, when asked for help(filter) :
Help on built-in function filter in module __builtin__:
filter(...)
Gediminas Kregzde a écrit :
Hello,
I'm Vilnius college II degree student and last semester our teacher
introduced us to python
I've used to program with Delphi, so I very fast adopted to python
Now I'm developing cross platform program and use huge amounts of
data. Program is needed to run as
Jaime Fernandez del Rio wrote:
(1) building another throwaway list and
(2) function call overhead for calling doit()
You can avoid (1) by using filter() instead of map()
Are you sure of this?
I'm afraid there is no builtin function to do an inplace modification
of a sequence...
You
Gediminas Kregzde wrote:
Hello,
I'm Vilnius college II degree student and last semester our teacher
introduced us to python
I've used to program with Delphi, so I very fast adopted to python
Now I'm developing cross platform program and use huge amounts of
data. Program is needed to run as
Marco Mariani wrote:
Gediminas Kregzde wrote:
def doit(i):
pass
def main():
a = [0] * 1000
t = time()
map(doit, a)
print map time: + str(time() - t)
Here you are calling a function ten million times, build a list with of
ten million None results, then throw it away.
norseman wrote:
div class=moz-text-flowed style=font-family: -moz-fixedMarco
Mariani wrote:
Gediminas Kregzde wrote:
def doit(i):
pass
def main():
a = [0] * 1000
t = time()
map(doit, a)
print map time: + str(time() - t)
Here you are calling a function ten million
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