1st file

import matplotlib.pyplot as plt
import numpy as np
from scipy import optimize
get_ipython().run_line_magic('matplotlib', 'inline')
fig,ax = plt.subplots(figsize=(16,8))
f=np.poly1d([5,1])
x=np.linspace(0,20,30)
y=f(x)+6*np.random.normal(size=len(x))
m,c=np.polyfit(x,y,1)
xn=np.linspace(0,20,200)
yn=np.polyval([m,c],xn)

##see the legend carefully, then open the another code and do side by side comparison##

ax.plot(x,y,"ob",label="data")
ax.plot(xn,yn,label="polyfit",color="black")
ax.plot(x,y,label="ntg")
ax.plot(xn_1,yn,"red",label="polyfit12",)
ax.legend(ncol=2)