needAdd multivariate linear regression example to README

[Dharshini77809]

import matplotlib.pyplot as plt
import numpy as np
from sklearn import linear_model
from sklearn.datasets import load_diabetes
from sklearn.model_selection import train_test_split

Load dataset

data = load_diabetes()
X = data.data
y = data.target

Split dataset

X_train, X_test, y_train, y_test = train_test_split(
X, y, test_size=0.4, random_state=1
)

Model

reg = linear_model.LinearRegression()
reg.fit(X_train, y_train)

print("Coefficients:", reg.coef_)
print("Variance score:", reg.score(X_test, y_test))

plt.scatter(reg.predict(X_train), reg.predict(X_train) - y_train,
color="green", s=10, label="Train data")

plt.scatter(reg.predict(X_test), reg.predict(X_test) - y_test,
color="blue", s=10, label="Test data")

plt.hlines(y=0, xmin=0, xmax=400, linewidth=2)

plt.legend(loc="upper right")
plt.title("Residual Errors")
plt.show()