cost_functiion_lr.py

from numpy import *

# y = mx + b
# m is slope, b is y-intercept
# point is tuple of x,y value at a given step with data as points[i]= [xi, yi]
def compute_error_for_line_given_points(b, m, points):
    totalError = 0
    for i in range(0, len(points)):
        x = points[i, 0]
        y = points[i, 1]
        totalError += (y - (m * x + b)) ** 2
    return totalError / float(len(points))