Re: How to get a matrix values' indices?

[Keith Goodman]

> x
x =

  1  2  3
  1  2  2
  1  1  3

> [i,j] = find(x==1);
> [i j]
ans =

  1  1
  2  1
  3  1
  3  2

> mean([i j])
ans =

  2.2500  1.2500

>



On Tue, 28 Sep 2004 20:12:53 +0200, Mikolaj Karolczak
<address@hidden> wrote:
> Hello,
> 
> Suppose we have a matrix of integer values. Is there any function to get 
> quickly
> matrices of each value's indices?
> 
> e.g.
> 
> I have:
> [1 2 3
>  1 2 2
>  1 1 3]
> 
> I want:
> -> 1: [1 1; 2 1; 3 1; 3 2]
> -> 2: [1 2; 2 2; 2 3]
> -> 3: [1 3; 3 3]
> 
> Surely I can get it by checking the value for every index but for big matrices
> if works slowly.
> 
> Actually I need to calculate the 'specific gravity' of each value in the 
> matrix
> - the mean values of each value's indices. Maybe there is a function to do it
> yet simplier?
> 
> Rgds,
> Mikolaj
> 
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