显示Matplotlib流图的子图颜色条

Question

What I want to do is simple: for a plot created using plt.subplots() I would like to display a color bar.

So, this is what I do:

def plotVF(self, u, v):
    m = np.sqrt(np.power(u, 2) + np.power(v, 2))

    xrange = np.linspace(0, u.shape[1], u.shape[1]);
    yrange = np.linspace(0, u.shape[0], u.shape[0]);

    x, y = np.meshgrid(xrange, yrange)
    mag = np.hypot(u, v)
    scale = 1
    lw = scale * mag / mag.max()

    f, ax = plt.subplots()
    h = ax.streamplot(x, y, u, v, color=mag, linewidth=lw, density=3, arrowsize=1, norm=plt.Normalize(0, 70))
    ax.set_xlim(0, u.shape[1])
    ax.set_ylim(0, u.shape[0])
    ax.set_xticks([])
    ax.set_yticks([])
    cbar = f.colorbar(h, ax=ax)
    cbar.ax.tick_params(labelsize=5) 

    plt.show()

Accordingly to what is shown in the docs . However, I keep receiving:

AttributeError: 'StreamplotSet' object has no attribute 'autoscale_None'

This example has only one plot, but I'll have more than one, that's why I'm not directly using plt.colorbar().

Answer 1

ax.streamplot returns a StreamplotSet object. This is not a mappabple instance that can be used in the making of a colorbar . However, as per the docs for streamplot , it contains the LineCollection and a collection of FancyArrowPatch objects. We can use the LineCollection to make the colorbar.

It can be accessed from you h , using h.lines . Thus, to make your colorbar, you need:

cbar = f.colorbar(h.lines, ax=ax)

You can see an example of this in the matplotlib gallery, here .