list comprehension question

[Kevin Anthony]

Is it not true that list comprehension is much faster the the for loops?

If it is not the correct way of doing this, i appoligize.
Like i said, I'm learing list comprehension.

Thanks
Kevin
On Oct 16, 2012 10:14 PM, "Dave Angel" <d at davea.name> wrote:

> On 10/16/2012 09:54 PM, Kevin Anthony wrote:
> > I've been teaching myself list comprehension, and i've run across
> something
> > i'm not able to convert.
> >
> > here's the original code for matrix multiplcation
> >
> > retmatrix = Matrix(self.__row,other.__col)
> > for m in range(0,retmatrix.__row):
> >     for n in range(0,retmatrix.__col):
> >         product = 0
> >         for p in range(1,self.__col+1):
> >             product += (self.__matrix[m][p] * other.__matrix[p][n])
> >         retmatrix.__matrix[m][n] = product
> >
> > Here is what i have so far:
> > retmatrix.__matrix = [[ product = product + (self.__matrix[m][p]*
> > other.__matrix[p][n])
> >                  if product else self.__matrix[m][p]*
> other.__matrix[p][n])
> >                  for p in range(0,self.col)
> >                  for n in range(0,self.col)]
> >                  for m in range(0,self.__row)]
> >
> > But i know that isn't correct, can someone nudge my in the right
> direction?
> >
> >
>
> The biggest thing to learn about list comprehensions is when not to use
> them.  I can't imagine how your latter version (even if correct) is
> clearer than the first.
>
>
>
> --
>
> DaveA
>
>
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