Printing the equation of the best fit line
So you need to write some function that convert a poly parameters array to a latex string, here is an example:
import pylab as plimport numpy as npx = np.random.randn(100)y = 1 + 2 * x + 3 * x * x + np.random.randn(100) * 2poly = pl.polyfit(x, y, 2)def poly2latex(poly, variable="x", width=2): t = ["{0:0.{width}f}"] t.append(t[-1] + " {variable}") t.append(t[-1] + "^{1}") def f(): for i, v in enumerate(reversed(poly)): idx = i if i < 2 else 2 yield t[idx].format(v, i, variable=variable, width=width) return "${}$".format("+".join(f()))pl.plot(x, y, "o", alpha=0.4)x2 = np.linspace(-2, 2, 100)y2 = np.polyval(poly, x2)pl.plot(x2, y2, lw=2, color="r")pl.text(x2[5], y2[5], poly2latex(poly), fontsize=16)Here is the output:
Here's a one liner.
If fit is the poly1d object, while plotting the fitted line, just use label argument as bellow,
label='y=${}$'.format(''.join(['{}x^{}'.format(('{:.2f}'.format(j) if j<0 else '+{:.2f}'.format(j)),(len(fit.coef)-i-1)) for i,j in enumerate(fit.coef)]))