test.py

import scipy as sp
import matplotlib.pyplot as plt

def error(f,x,y):
    return sp.sum((f(x)-y)**2)


data = sp.genfromtxt("E:\\MLPY\\book1\\ch01\\data\\web_test.tsv",delimiter="\t")
inflection = 3.5*7*24 #inflection point
inflection=int(inflection)

print(inflection)

x=data[:,0]
y=data[:,1]
x=x[~sp.isnan(y)]
y=y[~sp.isnan(y)]


xa = x[:inflection]
ya = y[:inflection]
xb = x[inflection:]
yb = y[inflection:]

fb = sp.poly1d(sp.polyfit(xb,yb,1))

fp1b = sp.polyfit(xb,yb,1)
f1b = sp.poly1d(fp1b)

fp2b = sp.polyfit(xb,yb,2)
f2b = sp.poly1d(fp2b)

fp3b = sp.polyfit(xb,yb,3)
f3b = sp.poly1d(fp3b)

fbe1 = error(f1b,xb,yb)
fbe2 = error(f2b,xb,yb)
fbe3 = error(f3b,xb,yb)

print("Error for 2nd Phase")
print("Error 1: %s",fbe1)
print("Error 2: %s",fbe2)
print("Error 3: %s",fbe3)