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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답변 (2개)
Nasser M. Abbasi
2012년 12월 1일
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
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Jan
2017년 4월 18일
@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
2017년 4월 18일
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
2012년 12월 1일
편집: Walter Roberson
2012년 12월 1일
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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