import numpy from sklearn.metrics import r2_score x = [89,43,36,36,95,10,66,34,38,20,26,29,48,64,6,5,36,66,72,40] y = [21,46,3,35,67,95,53,72,58,10,26,34,90,33,38,20,56,2,47,15] mymodel = numpy.poly1d(numpy.polyfit(x, y, 3)) print(r2_score(y, mymodel(x)))