Created
December 2, 2019 06:03
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Matplotlib quiver from stackoverflow
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from __future__ import division, print_function | |
import numpy as np | |
import matplotlib.pyplot as plt | |
def elec_field(x, y, x_coords=[0], y_coords=[0], charges=[1]): | |
Ex = np.zeros_like(x) | |
Ey = np.zeros_like(x) | |
for x0, y0, q in zip(x_coords, y_coords, charges): | |
R = np.sqrt((x - x0)**2 + (y - y0)**2) + 1e-6 | |
Ex += q*(x - x0)/R**3 | |
Ey += q*(y - y0)/R**3 | |
return Ex, Ey | |
y, x = np.mgrid[-3:3:21j, -3:3:21j] | |
Ex, Ey = elec_field(x, y, x_coords=[-1, 1], y_coords=[0,0], | |
charges=[1, -1]) | |
Emag = np.sqrt(Ex**2 + Ey**2) | |
dir_x = Ex/Emag | |
dir_y = Ey/Emag | |
plt.figure(figsize=(8, 6)) | |
plt.subplot(221) | |
plt.quiver(x[::2, ::2], y[::2, ::2], dir_x[::2, ::2], dir_y[::2, ::2], | |
np.log10(Emag[::2, ::2]), cmap="autumn", scale_units="inches", | |
scale=5, width=0.015, pivot="mid") | |
plt.colorbar() | |
plt.axis("image") | |
plt.subplot(222) | |
plt.streamplot(x, y, Ex, Ey, color=np.log10(Emag),cmap="autumn") | |
plt.colorbar() | |
plt.axis("image") | |
plt.subplot(223) |
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