17 lines
479 B
Matlab
17 lines
479 B
Matlab
function [Ynorm, Ymean] = normalizeRatings(Y, R)
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%NORMALIZERATINGS Preprocess data by subtracting mean rating for every
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%movie (every row)
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% [Ynorm, Ymean] = NORMALIZERATINGS(Y, R) normalized Y so that each movie
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% has a rating of 0 on average, and returns the mean rating in Ymean.
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%
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[m, n] = size(Y);
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Ymean = zeros(m, 1);
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Ynorm = zeros(size(Y));
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for i = 1:m
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idx = find(R(i, :) == 1);
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Ymean(i) = mean(Y(i, idx));
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Ynorm(i, idx) = Y(i, idx) - Ymean(i);
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end
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end
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