crypto-stackexchange-a-50480.py

#!/usr/bin/env python3

import numpy as np
import matplotlib
import matplotlib.pyplot as plt

def set_axes():
    axes = plt.gca()
    axes.set_xlim([-0.25,6.25])
    axes.set_ylim([0,50])
    return axes

def plot1():
    x_poly = np.linspace(-1, 7)
    y1 = 4*x_poly**2 - 25*x_poly + 42
    x_points = np.arange(1, 7)
    y2 = (4*x_points**2 + 25*x_points + 42) % 50

    print(*zip(x_points, y2))

    plt.plot(x_poly, y1, color="grey")
    plt.plot([0], [42], 'ro')
    plt.plot(x_points, y2, 'go')

    set_axes()
    fig = matplotlib.pyplot.gcf()
    fig.set_size_inches(5.0, 4.0)
    fig.savefig('image1.png', dpi=100)
    fig.clf()

def plot2():
    x_poly = np.linspace(-1, 7)
    y1 = 4*x_poly**2 - 25*x_poly + 42

    plt.plot(x_poly, y1, color="grey")
    plt.plot([4, 1, 2], [6, 21, 8], 'go')

    set_axes()
    fig = matplotlib.pyplot.gcf()
    fig.set_size_inches(5.0, 4.0)
    fig.savefig('image2.png', dpi=100)
    fig.clf()

def plot3():
    x_poly = np.linspace(-1, 7)
    y1 = 4*x_poly**2 - 25*x_poly + 42

    plt.plot(x_poly, y1, color="grey")
    plt.plot([0], [42], 'ro')

    set_axes()
    fig = matplotlib.pyplot.gcf()
    fig.set_size_inches(5.0, 4.0)
    fig.savefig('image3.png', dpi=100)
    fig.clf()

plot1()
plot2()
plot3()