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pythonnumpyregressionloglog
mikael
mikael

Reputation: 2317

numpy loglog linear regression

What is the best way to find the linear regression of loglog data using numpy? When I plot the data and try 

A = np.vstack([np.log10(X), np.ones(len(X))]).T
m, c = np.linalg.lstsq(A, np.log10(Y))[0]
ax.plot(X, [m*x + c for x in X], 'r')

where X and Y are the data lists, this is the result, obviously incorrect: enter image description here

Upvotes: 0

Views: 1273

Answers (1)

Warren Weckesser
Warren Weckesser

Reputation: 114811

If you do a linear regression on

log10(y) = m*log10(x) + c

then in (x,y) coordinates you have

y = (10**c) * x**m

That is, you have fit a power law to your data. Change this

ax.plot(X, [m*x + c for x in X], 'r')

to

ax.plot(X, np.power(10, c) * np.power(X, m), 'r')

Upvotes: 1

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