Re: [functional approach should give] an even faster way to normalize
- To: mathgroup at smc.vnet.net
- Subject: [mg85666] Re: [functional approach should give] an even faster way to normalize
- From: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>
- Date: Tue, 19 Feb 2008 01:48:48 -0500 (EST)
- References: <fp9945$199$1@smc.vnet.net>
Hi,
what is with
Map[
If[Min[#]>=0 && Max[#]<=1,#,{0,0,0}] &,
sum,
{2}
]
it is still more compact.
Regards
Jens
congruentialuminaire at yahoo.com wrote:
> Hello UG:
>
> I have a 512x512 array of 3-tuples. I want to make any tuple with a
> value outside of 0 <--> 1, become {0.,0.,0.}.
>
> The first version has this loop:
>
> For[i = 1, i <= graphSize, i++,
> For[j = 1, j <= graphSize, j++,
> If[((sum[[i, j, 1]] < 0) || (sum[[i, j, 1]] > 1) ||
> (sum[[i, j, 2]] < 0) || (sum[[i, j, 2]] > 1) ||
> (sum[[i, j, 3]] < 0) || (sum[[i, j, 3]] > 1)),
> sum[[i, j]] = {0., 0., 0.}
> ]
> ]
> ];
>
> After scratching my head for a while I came up with this (equivalent)
> Map statement.
>
> sum = Map[
> If[#[[1]] < 0 || #[[1]] > 1 || #[[2]] < 0 || #[[2]] > 1 || #[[3]] <
> 0 || #[[3]] > 1, {0., 0., 0.}, #] &, sum, {2}];
>
> It is faster but only by about 15%.
>
> It is unreasonable to believe some other construction can accomplish
> this with a bigger payoff?
>
> Thanks in advance.
>
> Regards..Roger W.
>