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Re: reducing the time of constructing a List


On a 800Mhz iMac, Mathematica 5.1, OS X 10.4.1 I get


dat = Table[Random[Integer, {0, 10}], {100000}];

In[12]:=
lst1=Replace[dat,{x_/;x=!=1 \[Rule]0},{1}];//Timing

Out[12]=
{0.396968 Second,Null}

Adriano Pascoletti

Il giorno 31 mag 2005, alle ore 11:00, marloo3 at mail15.com ha scritto:

> please, what is the best way to reduce the timing of the following  
> lines, the
> source of data is:
> dat = Table[Random[Integer, {0, 10}], {100000}];
> and the purpose is to construct the List lst in the following way:
> For[i = 1, i <= 100000,
>       If [dat[[i]] == 1,
>         lst = Join[lst, {1}], lst = Join[lst, {0}]]; i++]; // Timing
>
> Out[]= {226.07 Second, Null}
> on the P4 celeron 2 Ghz , memory 382 MB ram
> thanks
>
>


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