pandas - How to get prediction days, out of range of linear regression using python

Question

I am trying to display the number of days (prediction) out of range of linear regression. I have managed to display the data using matplotlib and created a predict() function to display the values based in the number of days but the data is outputting wrong, higher than the initial output. Since the straight line is aiming down and the higher value is 85.15.

import area as area
import pandas as pd
import numpy as np
import matplotlib.pyplot as plt
from matplotlib import colors
from sklearn import linear_model

# date = x, cases = y
# 1- Retrieve the data
df = pd.read_csv("cases-challenge.csv")
x = df.days

y = df.cases
# 2- Iterate the data

# get the mean of x and y
xmean = x.mean()
ymean = y.mean()

df['diffx'] = xmean - x
df['diffx_squared'] = df.diffx ** 2
SSxx = df.diffx_squared.sum()

df['diffy'] = ymean - y
SSxy = (df.diffx * df.diffy).sum()

m = SSxx / SSxy
b = ymean - m * xmean


def predict(value):
    # value = x
    for i in range(value):
        # straight line = m*x+y
       print(i, ':', m * i + b)


predict(6)

plt.scatter(x, y)
plt.plot(x, m*x+b, 'r')
plt.show()

The input cases-challenge.csv:

days, cases
18,   85.15
19,   83.5
20,   82.5
21,   80.73
22,   78.77
23,   77.86
24,   75.96
25,   75.85
26,   74.79
27,   72.79

output in terminal using 6 as value in the predict():

0 : 95.61300163132137
1 : 94.86531266992931
2 : 94.11762370853725
3 : 93.36993474714518
4 : 92.62224578575312
5 : 91.87455682436106

Matplotlib output:

question from:https://stackoverflow.com/questions/65949119/how-to-get-prediction-days-out-of-range-of-linear-regression-using-python

Answer 1

Waitting for answers