Change color limits with quiver in matplotlib?

问题

How should the syntaxis be for changing the limits of the color range when plotting with quivers in matplotlib? I have the following code:

PyPlot.ion()
xlim(1, 64)
ylim(1, 64)
flechitas = quiver(x, y, EFx, EFy, sqrt((EFx.*EFx+EFy.*EFy)),
        pivot="middle", cmap="Blues")
cb=colorbar(flechitas)

Which produces an adecuate image but uses automatically detected range for the 5th argument (the color). In the manual of matplotlib it says that I can use the clim keyword but if I put it inside the arguments or outside, after the xy limits, I get an error indicating that I must create an image first, with imageshow. If I do that, then I get a more obscure error, an AssertionError(). My matplotlib is 1.3.1.

回答1:

Okey, I got it, this is the right way to do it with matplotlib 1.3.1

figure()
xlim(1,64)
ylim(1,64)
flechitas=quiver(x,y,EFx,EFy, sqrt((EFx.*EFx+EFy.*EFy)), units="x", 
pivot="middle", cmap="Blues", width=0.4);
cb=colorbar(flechitas, clim(0,120));

So, clim(min, max) must be an argument to colorbar(...), it seems.

回答2:

Use the matplotlib function clim():

plt.clim(0,120)

Extended example:

import matplotlib.pyplot as plt
import numpy as np

X, Y = np.meshgrid(np.arange(0, 2 * np.pi, .2), np.arange(0, 2 * np.pi, .2))
U = np.cos(X)
V = np.sin(Y)
M = np.hypot(U, V)

plt.figure(figsize=(17,5))
plt.subplot(121)
Q = plt.quiver(X, Y, U, V, M)
plt.colorbar()
plt.subplot(122)
Q = plt.quiver(X, Y, U, V, M)
plt.colorbar()
plt.clim(0,1)

来源：https://stackoverflow.com/questions/31280498/change-color-limits-with-quiver-in-matplotlib