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