matrix normalization in matlab

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jenifer
jenifer 2013-1-30
评论： DGM 2024-8-3
hi.. i want normalize a matrix (129 x 128)..please help me with matlab codes

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Thorsten
Thorsten 2013-1-30
To normalize a matrix such that all values fall in the range [0, 1] use
Anorm = (A - min2(A))/(max2(A) - min2(A));
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Irawati Roy
Irawati Roy 2022-12-11
You missed a dot before the division operation for a 2d matrix
DGM
DGM 2022-12-11
编辑：DGM 2022-12-11
There ./ is not needed here, since the denominator is a scalar.
That said, there is no function called min2() or max2(), nor can I find evidence that there were functions by those names which have since been removed. Maybe they used to be part of one of the toolboxes.
Alternatively, you could do:
Anorm = (A - min(A(:)))/(max(A(:)) - min(A(:)));
or you could do
Anorm = (A - min(A,[],'all'))/(max(A,[],'all') - min(A,[],'all'));
though the latter option wouldn't have worked circa 2013

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Matt J
Matt J 2013-1-30
You need to decide how you want to define the amplitude of the matrix first. Maybe you want this
normalized = A/norm(A);
or maybe this
normalized = A/max(abs(A(:)))
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jenifer
jenifer 2013-1-30
ya... but how can i get a single value from whole matrix...
Jan
Jan 2013-1-30
Please, jenifer, we have asked you to define "normalization" exactly. It wastes time if we guess what you mean.

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Jing
Jing 2013-1-30
You can use 'normc' or 'normr' for normalization. 'c' or 'r' stands for columns or rows that you want to normalize.
DGM
DGM 2022-12-11
Ran in:
Since R2018a, you can use normalize() to perform normalization in various different ways.
A = 1:6
A = 1×6
1 2 3 4 5 6
B1 = normalize(A,'range') % default range is [0 1]
B1 = 1×6
0 0.2000 0.4000 0.6000 0.8000 1.0000
B2 = normalize(A,'range',[-1 2]) % but you can specify any range
B2 = 1×6
-1.0000 -0.4000 0.2000 0.8000 1.4000 2.0000
B3 = normalize(A,'zscore','std') % zero-center and scale to have std=1
B3 = 1×6
-1.3363 -0.8018 -0.2673 0.2673 0.8018 1.3363
B4 = normalize(A,'norm',2) % normalize by vector p-norm (default p=2)
B4 = 1×6
0.1048 0.2097 0.3145 0.4193 0.5241 0.6290
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Sinan Islam
Sinan Islam 2024-8-3
The normalize function in matlab either works on columns or rows. We want a function that normalizes the matrix as a whole. We are not looking for normalizing features or observations. So the calculation must be made on global minimum and global maximum of the matrix. Thats why we flatten the matrix into one vector before doing any calculation.
DGM
DGM 2024-8-3
As others have mentioned, "normalize" is a terribly vague word. If the goal is to rescale the entire array with respect to global statistics, then yes, reshaping the array is one way to do so.

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