18 lines
514 B
Matlab
18 lines
514 B
Matlab
function [Xn, mu, sigma] = preprocess_data(X, mu, sigma)
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% PREPROCESS_DATA Normalize feature matrix using z-score scaling
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%
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% [Xn, mu, sigma] = preprocess(X)
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% [Xn, mu, sigma] = preprocess(X, mu, sigma)
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%
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% Applies feature-wise standardization (zero mean, unit variance)
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% to the predictors only — labels Y remain unchanged.
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if nargin < 2 || isempty(mu)
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mu = mean(X,1);
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sigma = std(X,[],1);
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end
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sigma(sigma==0) = 1; % avoid division by zero
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Xn = (X - mu) ./ sigma;
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end
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