在matplotlib 2.0中，如何将颜色条行为还原为matplotlib 1.5？

Question

I just upgraded to matplotlib 2.0 and in general, I'm very happy with the new defaults. One thing which I'd like to revert to the 1.5 behaviour is that of plt.colorbar , specifically the yticks. In the old matplotlib, only major ticks were plotted on my colorbars; in the new matplotlib, minor and major ticks are drawn, which I do not want.

Below is shown a comparison of the 1.5 behaviour (left) and the 2.0 behaviour (right) using the same colormap and logarithmic ticks.

What defaults do I need to set in matplotlibrc in order to revert to the 1.5 behaviour shown on the left? If there is no way to do this using matplotlibrc , what other avenues are available for altering this globally beyond downgrading to matplotlib 1.5?

I have tried simply setting cbar.ax.minorticks_off() after every instance of cbar = plt.colorbar(mesh) , but that doesn't solve the issue.

Answer 1

It should be sufficient to just set the colorbar locator to a LogLocator from the matplotlib.ticker module, and then call update_ticks() on the colorbar instance.

For example, consider this minimal example which produces the colorbar you are seeing with minor ticks:

import matplotlib.pyplot as plt
import matplotlib.ticker as ticker
import matplotlib.colors as colors
import numpy as np

fig, ax = plt.subplots(1)

# Some random data in your range 1e-26 to 1e-19
data = 10**(-26. + 7. * np.random.rand(10, 10))

p = ax.imshow(data, norm=colors.LogNorm(vmin=1e-26, vmax=1e-19))

cb = fig.colorbar(p, ax=ax)

plt.show()

If we now add the following two lines before calling plt.show() , we remove the minor ticks:

cb.locator = ticker.LogLocator()
cb.update_ticks()

Alternatively, to achieve the same thing, you can use the ticks kwarg when creating the colorbar, and set that to the LogLocator()

cb = fig.colorbar(p, ax=ax, ticks=ticker.LogLocator())