50 lines
708 B
C++
50 lines
708 B
C++
// Regression is a class to compute a linear regression
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//
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#include "regression.h"
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Regression::Regression()
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{
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init();
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}
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void Regression::init()
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{
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sumxx = 0;
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sumyy = 0;
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sumxy = 0;
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sumx = 0;
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sumy = 0;
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n = 0;
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}
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void Regression::point(float x, float y)
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{
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sumx = sumx + x;
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sumy = sumy + y;
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sumxx = sumxx + x * x;
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sumyy = sumyy + y * y;
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sumxy = sumxy + x * y;
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n = n + 1;
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}
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void Regression::regress()
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{
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float sxx = sumxx - sumx * sumx / n;
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float sxy = sumxy - sumx * sumy / n;
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b = sxy / sxx;
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a = (sumy - b * sumx) / n;
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}
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float Regression::f(float x)
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{
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return a + b * x;
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}
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float Regression::f_inv(float y)
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{
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return (y - a) / b;
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}
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