Scaling the natrix in specific range
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I have a 300x1 matrix
where the minmum value is
-2.1188e+003
maximum is
460.3171
i want to scale in region from -1 to 1
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Réponses (2)
Nasser M. Abbasi
le 1 Déc 2012
Since I just wrote the code, might as well post it. A quick function to scale it
function C = nma_rescale(A,new_min,new_max)
%Nasser M. Abbasi 011212
%NO ERROR CHECKING DONE ON INPUT. Rescale a matrix or a vector A
current_max = max(A(:));
current_min = min(A(:));
C =((A-current_min)*(new_max-new_min))/(current_max-current_min) + new_min;
end
to use:
EDU>> C=rand(3);
EDU>> B=nma_rescale(C,-1,1)
B =
-0.7625 0.8960 -0.2033
-0.3188 -0.8938 -1.0000
-0.8317 1.0000 -0.3316
6 commentaires
Jan
le 18 Avr 2017
@Dario: There is no convention. It depends on your problem, if the result of a scaled scalar is -1, 0, +1 or Inf, perhaps NaN.
Dario Dematties
le 18 Avr 2017
Thanks Jan, Does anyone know which is the reaction of libsvm software on matlab when it is fed with vectors with missing data (NaN)?
Walter Roberson
le 1 Déc 2012
Modifié(e) : Walter Roberson
le 1 Déc 2012
Does 0 need to remain 0, or should it become the midpoint of your [-2118.8 to 460.317] range?
0 remains 0:
matmin = min(mat);
matmax = max(mat);
newmat = mat;
newmat(mat < 0) = mat(mat < 0) ./ abs(minmat);
newmat(mat > 0) = mat(mat > 0) ./ maxmat;
Midpoint becomes 0:
matmin = min(mat);
matmax = max(mat);
newmat = 2 * (mat - matmin) ./ (matmax - matmin) - 1;
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