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lin_reg.py
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lin_reg.py
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'''
Formula:
Slope (b1) =
summation of (xi - x_mean) * (yi - ymean)
__________________________________________
summation of (xi - x_mean) ^ 2
Intercept (b0) =
mean_y - b1 * mean_x
'''
X = [69, 63, 66, 64, 67, 64, 70, 66, 68, 67, 65, 71]
Y = [70, 65, 68, 65, 69, 66, 68, 65, 71, 67, 64, 72]
meanX = sum(X)/len(X)
meanY = sum(Y)/len(Y)
numer = sum(map(lambda xy: (xy[0]-meanX)*(xy[1]-meanY),zip(X, Y)))
denom = sum(map(lambda x: (x-meanX)**2, X))
b1 = numer / denom
b0 = meanY - b1 * meanX
print('B1=', b1)
print('B0=', b0)
print('Line is:' f'Y = {b1}X + {b0}')
'''
Output:
B1= 0.859223300970874
B0= 10.218446601941729
Line is:Y = 0.859223300970874X + 10.218446601941729
'''
'''
Alternate Approach:
# sumXX = sum(map(lambda x: x**2, X))
# sumXY = sum(map(lambda x: x[0]*x[1], zip(X, Y)))
# print('sum(X) =', sumX)
# print('sum(X^2)=', sumXX)
# print('sum(Y) =', sumY)
# print('sum(XY) =', sumXY)
# sum Y = c * n + m * sum X
# sum XY = c * sumX + m * sum XX
# n = len(X)
# c = (sumY * sumXX - sumXY * sumX ) / (n * sumXX - sumX**2)
# print('m=', c)
'''
'''
Previous OUTPUT:
sum(X) = 800
sum(X^2)= 53402
sum(Y) = 810
sum(XY) = 54059
B1= 0.859223300970874
B0= 10.218446601941729
Line is:Y = 0.859223300970874X + 10.218446601941729
'''