Building Machine Learning Systems with Python - Third Edition

Stepping back to go forward - another look at our data

So, we step back and take another look at the data. It seems that there is an inflection point between weeks 3 and 4. Let's separate the data and train two lines using week 3.5 as a separation point:

>>> inflection = int(3.5*7*24) # calculate the inflection point in hours>>> xa = x[:inflection] # data before the inflection point>>> ya = y[:inflection]>>> xb = x[inflection:] # data after>>> yb = y[inflection:]>>> fa = sp.poly1d(sp.polyfit(xa, ya, 1))>>> fb = sp.poly1d(sp.polyfit(xb, yb, 1))>>> fa_error = error(fa, xa, ya)>>> fb_error = error(fb, xb, yb)>>> print("Error inflection=%f" % (fa_error + fb_error))Error inflection=132950348.197616

From the first line (straight), we train with ...