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Re: Map function with 2 variables

  • To: mathgroup at smc.vnet.net
  • Subject: [mg114967] Re: Map function with 2 variables
  • From: Andrzej Kozlowski <akoz at mimuw.edu.pl>
  • Date: Fri, 24 Dec 2010 04:13:35 -0500 (EST)
  • References: <201012230856.DAA05031@smc.vnet.net>

On 23 Dec 2010, at 09:56, Jagra wrote:

> I have a problem that comes up in a couple of situations and I've
> never found the right solution.  I hoped I could get an idea of how to
> generally address these kinds of things.
> 
> Say I have a function with two variables, something like a
> SpearmanRankCorrelation[] from the MultiVariate Statistics package:
> 
> I also have matrix "m" with dimensions {3, 100}
> 
> m = RandomReal[{0, 1}, {3, 100}];
> 
> Now, say I want to create a correlation matrix using the
> SpearmanRankCorrelation function.
> 
> I can get the rank correlations between a single vector of the matrix
> and all the other vectors like this:
> 
> SpearmanRankCorrelation[m[[1]], #] & /@ m
> 
> This would give me a single row in a correlation matrix.   Pretty
> straightforward, but now I want all 3 rows like I would get with this:
> 
> {SpearmanRankCorrelation[m[[1]], #] & /@ m,
> SpearmanRankCorrelation[m[[2]], #] & /@ m,
> SpearmanRankCorrelation[m[[3]], #] & /@ m}
> 
> There must be a way I can do this more directly.
> I must be missing something simple.
> 
> Thanks.
> 

Needs["MultivariateStatistics`"]

m = RandomReal[{0, 1}, {3, 100}];

then

Function[z, (SpearmanRankCorrelation[z, #1] & ) /@ m] /@ m

{{1, -(4441/27775), 763/83325}, {-(4441/27775), 1, 
     -(7553/83325)}, {763/83325, -(7553/83325), 1}}

or

Outer[SpearmanRankCorrelation[#1, #2] & , m, m, 1]

{{1, -(4441/27775), 763/83325}, {-(4441/27775), 
  1, -(7553/83325)}, 
   {763/83325, -(7553/83325), 1}}



Andrzej Kozlowski


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