这篇文章主要介绍了 python+matplotlib 演示电偶极子实例代码, 具有一定借鉴价值, 需要的朋友可以参考下
使用 matplotlib.tri.CubicTriInterpolator. 演示变化率计算:
完整实例:
- from matplotlib.tri import (
- Triangulation, UniformTriRefiner, CubicTriInterpolator)
- import matplotlib.pyplot as plt
- import matplotlib.cm as cm
- import numpy as np
- #-----------------------------------------------------------------------------
- # Electrical potential of a dipole
- #-----------------------------------------------------------------------------
- def dipole_potential(x, y):
- """The electric dipole potential V"""
- r_sq = x**2 + y**2
- theta = np.arctan2(y, x)
- z = np.cos(theta)/r_sq
- return (np.max(z) - z) / (np.max(z) - np.min(z))
- #-----------------------------------------------------------------------------
- # Creating a Triangulation
- #-----------------------------------------------------------------------------
- # First create the x and y coordinates of the points.
- n_angles = 30
- n_radii = 10
- min_radius = 0.2
- radii = np.linspace(min_radius, 0.95, n_radii)
- angles = np.linspace(0, 2 * np.pi, n_angles, endpoint=False)
- angles = np.repeat(angles[..., np.newaxis], n_radii, axis=1)
- angles[:, 1::2] += np.pi / n_angles
- x = (radii*np.cos(angles)).flatten()
- y = (radii*np.sin(angles)).flatten()
- V = dipole_potential(x, y)
- # Create the Triangulation; no triangles specified so Delaunay triangulation
- # created.
- triang = Triangulation(x, y)
- # Mask off unwanted triangles.
- triang.set_mask(np.hypot(x[triang.triangles].mean(axis=1),
- y[triang.triangles].mean(axis=1))
- < min_radius)
- #-----------------------------------------------------------------------------
- # Refine data - interpolates the electrical potential V
- #-----------------------------------------------------------------------------
- refiner = UniformTriRefiner(triang)
- tri_refi, z_test_refi = refiner.refine_field(V, subdiv=3)
- #-----------------------------------------------------------------------------
- # Computes the electrical field (Ex, Ey) as gradient of electrical potential
- #-----------------------------------------------------------------------------
- tci = CubicTriInterpolator(triang, -V)
- # Gradient requested here at the mesh nodes but could be anywhere else:
- (Ex, Ey) = tci.gradient(triang.x, triang.y)
- E_norm = np.sqrt(Ex**2 + Ey**2)
- #-----------------------------------------------------------------------------
- # Plot the triangulation, the potential iso-contours and the vector field
- #-----------------------------------------------------------------------------
- fig, ax = plt.subplots()
- ax.set_aspect('equal')
- # Enforce the margins, and enlarge them to give room for the vectors.
- ax.use_sticky_edges = False
- ax.margins(0.07)
- ax.triplot(triang, color='0.8')
- levels = np.arange(0., 1., 0.01)
- cmap = cm.get_cmap(name='hot', lut=None)
- ax.tricontour(tri_refi, z_test_refi, levels=levels, cmap=cmap,
- linewidths=[2.0, 1.0, 1.0, 1.0])
- # Plots direction of the electrical vector field
- ax.quiver(triang.x, triang.y, Ex/E_norm, Ey/E_norm,
- units='xy', scale=10., zorder=3, color='blue',
- width=0.007, headwidth=3., headlength=4.)
- ax.set_title('Gradient plot: an electrical dipole')
- plt.show()
来源: http://www.phperz.com/article/18/0216/362732.html