如何通过 secondary_yaxis 设置轴标签的格式？

Question

如何通过secondary_yaxis设置轴标签的格式？

在下面的示例中，我希望更多地控制第二个轴标签（例如 format='%g'）。我认为应该可以将ticklabel_format 或format 之类的东西作为kwargs 传递，但似乎都不起作用（两者都提高AttributeError: 'SecondaryAxis' object has no property ...）。

    import matplotlib.pyplot as plt
    import numpy as np

    # Conversion functions to and from km and hPa
    def km2hPa(input):
        return np.exp( input / -7.6 ) * 1013.

    def hPa2Km(input):
        return -7.6 * np.log( input  / 1013. )

    # Fake data to plot
    Y = np.linspace(1000, 100, 100)
    X = np.array( [i**2 for i in np.linspace(0, 10, len(Y)) ] )

    # Plot up data with both primary (hPa) and secondary axis (km)
    plt.close('all')
    kwargs = {} # Add a format specifier here?
    fig, ax = plt.subplots()
    plt.plot(X, Y)
    ax.set_ylabel('Pressure altitude (hPa)')
    ax.invert_yaxis()
    secax = ax.secondary_yaxis('right', functions=(hPa2Km, km2hPa), **kwargs)
    secax.set_ylabel('Altitude (km)')
    plt.show()

Answer 1

import matplotlib.ticker as ticker

secax.yaxis.set_major_formatter(ticker.StrMethodFormatter("{x:g}"))

或

secax.yaxis.set_major_formatter(ticker.FormatStrFormatter("%g"))