test_plot_obj.py

#!/usr/bin/env python3
""" Exercises plot_obj.py module, demonstrating its use within a program. 

First draws some mathematical curves and then allows the user to place circles
of radiating arrows of random colors and sizes when the  clicks the mouse over
the window
"""

from plot_obj import Plotter
from math import sin

def quad(x):
    """ Quadratic function (parabola) """
    return 1/2 * x ** 2 + 3

def arrow_wheel(plotter, x, y, len, angle, color):
    """
    Draws a collection of arrows extending radially from an (<x>, <y>) center
    point.
    The arrows all are <len> long, the <angle> parameter specifies the angle 
    between each adjacent arrow, and <color> specifies their color.
    """
    from math import cos, sin, radians

    COS_theta = cos(radians(angle))
    SIN_theta = sin(radians(angle))
    plotter.setcolor(color)
    xe, ye = len, 0.0
    for i in range(360 // angle):
        xe, ye = xe * COS_theta - ye * SIN_theta, \
                xe * SIN_theta + ye * COS_theta

        plotter.draw_arrow(x, y, xe + x, ye + y)

def main():
    """ Provides a simple test of the plotting object """
    from math import sin

    def run_test(x, y):
        """
        Generate an arrow wheel centered at (<x>, <y>) width
        random size and color
        """
        # test_arrow(plt)
        from random import randrange
        colors = ['red', 'green', 'blue', 'black']
        arrow_wheel(plt, x, y, randrange(10) + 1, 10, colors[randrange(4)])

    # Create a plotter object
    plt = Plotter(600, 600, -10, 10, -10, 10)

    # Plot f(x) = 1/2 * x + 3, for -10 <= x < 100
    plt.plot_function(quad, 'red')

    # Plot f(x) = x, for -10 <= x < 100
    plt.plot_function(lambda x: x, 'blue')

    # Plot f(x) = 3 sin x, for -10 <= x < 100
    plt.plot_function(lambda x: 3 * sin(x), 'green')
    
    # Excecute the run_test function when the user clicks the mouse
    plt.onclick(run_test)
    # test_arrow(plt)

    plt.interact()

if __name__ == '__main__':
    main()