cours_progra/bac1/q1/29sept/plot.py

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2022-09-29 17:42:52 +02:00
#!/usr/bin/env python3
import matplotlib.pyplot as plt
import numpy as np
class Plot(object):
"""Show graphical drawing of lines from their equation."""
def __init__(self):
self.setXAxis()
self.functs = []
self.verts = []
def prepare(self, line):
"""Add the given line to the plot.
The line is not shown until the method show is called.
Args:
line: a triplet `(a, b, c)` representing the coefficients of the
line of equation `ax + bx + c = 0`.
"""
a, b, c = line
if b == 0:
if a == 0:
raise ValueError('Not a line.')
else:
self.verts.append(line)
else:
self.functs.append(line)
def setXAxis(self, xmin=-10, xmax=10):
self.xmin = xmin
self.xmax = xmax
def reset(self):
self.setXAxis()
self.functs = []
self.verts = []
def plot(self, t, y, line):
a, b, c = line
plt.plot(t, y, label='%.4g*x + %.4g*y = %.4g' % (a, b, c))
def draw(self):
for a, b, c in self.functs:
t = np.array([self.xmin, self.xmax])
y = (-a * 1.0 / b) * t + (c * 1.0 / b)
self.plot(t, y, (a, b, c))
for a, b, c in self.verts:
x = c / a
self.plot([x, x], plt.ylim(), (a, b, c))
plt.axis('tight')
plt.legend()
plt.title('Exercices sur les droites')
plt.xlabel('x')
plt.ylabel('y')
plt.grid(True)
def save(self, filename):
self.draw()
plt.savefig(filename)
def show(self):
self.draw()
plt.show()
if __name__ == '__main__':
p = Plot()
p.prepare((1, 1, 3))
p.prepare((-2, 1, -1))
p.prepare((1, 0, -5))
p.show()
input()