[Scilab-users] vectoriztion and sets of data

[Paul Carrico]

Thanks for your suggestion ; it’s is interesting for another specific
development
 unfortunately I don’t think I cannot adapt that code for my
project !

 

Indeed I need to work on sets of data (n rows of data at the same time to
select, to rearrange, to transform, to mean, etc. 
) on matrix on size on
X*n rows (X may be 100 000 
 ) ; currently I use loops as described above 



 the issue is to optimize the following line through vectorized “i” index:
Search = max(abs(C([i. * 8 - 7 : i. * 8],:)))

 

Si let ‘s rack one’s brains 


 

Thanks

 

Paul

 

De : users-bounces at lists.scilab.org [mailto:users-bounces at lists.scilab.org]
De la part de Adrien Vogt-Schilb
Envoyé : jeudi 22 novembre 2012 16:12
À : International users mailing list for Scilab.
Objet : Re: [Scilab-users] vectoriztion and sets of data

 

Hi again

I am still not sure, but look at the output of 

A = rand(8,6)

B = zeros(8,6)

D = A > B

D = bool2s (A > B)

This might give you insight on how to solve your problem
tell me if not

On 22/11/2012 16:06, Paul Carrico wrote:

The original code looked like 
 I’m trying to optimized it (ok for the “if”,
but how to combine a set of data and vectorization (??? Many trials but I
failed)

 

// initial matrix

A = rand(8,6);

B = zeros(8,6);

C = [A ; A; B; A; B; B; A];

[nr,nc] = size(C);

 

// original code looks like

D = zeros((nr/8),1);

for i = 1 : (nr/8)

    search = max(abs(C((8*(i-1)+1):(8*i),:)));

    if (search > 0) then

        D(i,1) = 1;

    else

        D(i,1) = 0;

    end

end

 

  

###################################################

mode(0)
 
// initial matrix
A = rand(8,6);
B = zeros(8,6);
C = [A ; A; B; A; B; B; A];
[nr,nc] = size(C);
 
// each set of 8 rows is analysed
Search = zeros((nr/8),1);
//i = ones((nr/8),1).* 1;
i = [1:(nr/8)]';
// Search = max(abs(C((8*(i - 1) + 1):(8 * i),:)));
Search = max(abs(C([i. * 8 - 7 : i. * 8],:)))
;
B = (find(Search == 0))';
 
D = zeros((nr/8),1);
D(B,2) = 1;

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