五彩线条

此示例显示如何制作多色线。 在此示例中，线条基于其衍生物着色。

五彩线条示例1

  1. import numpy as np
  2. import matplotlib.pyplot as plt
  3. from matplotlib.collections import LineCollection
  4. from matplotlib.colors import ListedColormap, BoundaryNorm
  6. x = np.linspace(0, 3 * np.pi, 500)
  7. y = np.sin(x)
  8. dydx = np.cos(0.5 * (x[:-1] + x[1:]))  # first derivative
  10. # Create a set of line segments so that we can color them individually
  11. # This creates the points as a N x 1 x 2 array so that we can stack points
  12. # together easily to get the segments. The segments array for line collection
  13. # needs to be (numlines) x (points per line) x 2 (for x and y)
  14. points = np.array([x, y]).T.reshape(-1, 1, 2)
  15. segments = np.concatenate([points[:-1], points[1:]], axis=1)
  17. fig, axs = plt.subplots(2, 1, sharex=True, sharey=True)
  19. # Create a continuous norm to map from data points to colors
  20. norm = plt.Normalize(dydx.min(), dydx.max())
  21. lc = LineCollection(segments, cmap='viridis', norm=norm)
  22. # Set the values used for colormapping
  23. lc.set_array(dydx)
  24. lc.set_linewidth(2)
  25. line = axs[0].add_collection(lc)
  26. fig.colorbar(line, ax=axs[0])
  28. # Use a boundary norm instead
  29. cmap = ListedColormap(['r', 'g', 'b'])
  30. norm = BoundaryNorm([-1, -0.5, 0.5, 1], cmap.N)
  31. lc = LineCollection(segments, cmap=cmap, norm=norm)
  32. lc.set_array(dydx)
  33. lc.set_linewidth(2)
  34. line = axs[1].add_collection(lc)
  35. fig.colorbar(line, ax=axs[1])
  37. axs[0].set_xlim(x.min(), x.max())
  38. axs[0].set_ylim(-1.1, 1.1)
  39. plt.show()

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