[Tutor] List Splicing

[Robert Berman]

Wayne,

Thank you for the suggestion. I will let you know how well this plays
out.

Robert




On Wed, 2009-06-17 at 19:26 -0500, Wayne wrote:
> On Wed, Jun 17, 2009 at 7:11 PM, Robert Berman <bermanrl at cfl.rr.com>
> wrote:
>         Emille,
>         
>         Thank you for the example of list splicing.  Do you know if
>         this is  faster than a more conventional loop statement as in
>         my code for primearray which is in my original post (reprinted
>         here)
>         
>         
>         The code is as follows:
>         
>         def BuildSieve(itemsin):
>             TheSieve=list()
>             TheSieve = range(0,itemsin+1)
>             TheSieve[1]=0
>             for i in range(2,itemsin+1):
>                 if (TheSieve[i] > 0):
>                     j = i + i
>                     while (j <= itemsin):
>                         TheSieve[j] = 0
>                         j+=i
>             return TheSieve
>         
>         It is called with PrimaryList = BuildSieve(1000000)
>         
> 
> I'm curious if it wouldn't be faster to use xrange. I know for certain
> instead of range(0, itemsin+1) you could use TheSieve = [1, 2]
> TheSieve.extend(range(3, itemsin+1,2))
> 
> Which would save you at least half the time in your generation. Since
> your first step should be removing multiples of two, that should be a
> big help.
> 
> HTH,
> Wayne
> 
>