how does the index works in this case

November 3, 2022

i cant understand how this specific line works in this programm

price += cabin[c.index(coefficient)]*coefficient

this programm is making a prediction about the price of 3 cabins considering some factors.(square m,distances form city ,bathrooms ,etc)

Each row in X represents 1 cabin ,so in X there are infos about 3 cabins in total

In C there are some values that correspond to the coefficient for every factor

X = [[66, 5, 15, 2, 500], 
     [21, 3, 50, 1, 100], 
     [120, 15, 5, 2, 1200]]
c = [3000, 200, -50, 5000, 100]    # coefficient values

def predict(X, c):
    price = 0 
    for cabin in X:
        for coefficient in c:
            price += cabin[c.index(coefficient)]*coefficient
        print(price)
        price = 0
               
predict(X, c)

`
the correct prices are

cabin 1 = 258250

cabin 2 = 76100

cabin 3 = 492750

my newbie approach was very simple ,typing each cabin alone ,so if i need 30 cabins i would type 30 different lines . I found the above answer online

>Solution :

Adding print lines like this helps you actually visualize what is going on.

There is a standard library for linear regression which is not only simple to use, has tons of extended functionality.

https://scikit-learn.org/stable/modules/generated/sklearn.linear_model.LinearRegression.html

X = [[66, 5, 15, 2, 500], 
     [21, 3, 50, 1, 100], 
     [120, 15, 5, 2, 1200]]
c = [3000, 200, -50, 5000, 100]    # coefficient values

def predict(X, c):
    price = 0 
    for cabin in X:
        for coefficient in c:
            print(f" 'price' variable = {price} + {cabin[c.index(coefficient)]} * {coefficient}", end = ' = ') # helps you visualize
            price += cabin[c.index(coefficient)]*coefficient
            print(f'{price}')
        print(price) #
        price = 0
               
predict(X, c)

Output:

 'price' variable = 0 + 66 * 3000 = 198000
 'price' variable = 198000 + 5 * 200 = 199000
 'price' variable = 199000 + 15 * -50 = 198250
 'price' variable = 198250 + 2 * 5000 = 208250
 'price' variable = 208250 + 500 * 100 = 258250
258250
 'price' variable = 0 + 21 * 3000 = 63000
 'price' variable = 63000 + 3 * 200 = 63600
 'price' variable = 63600 + 50 * -50 = 61100
 'price' variable = 61100 + 1 * 5000 = 66100
 'price' variable = 66100 + 100 * 100 = 76100
76100
 'price' variable = 0 + 120 * 3000 = 360000
 'price' variable = 360000 + 15 * 200 = 363000
 'price' variable = 363000 + 5 * -50 = 362750
 'price' variable = 362750 + 2 * 5000 = 372750
 'price' variable = 372750 + 1200 * 100 = 492750
492750