如何安全地修补 matplotlib 的轴（不影响以后的调用）？

Question

我有一个使用 bar3d 可视化矩阵元素的函数。 I was trying to remove margins at the bounding limits of z-axis. I found this answer（第一个）使用 猴子补丁。所以我的代码看起来像这样：

from mpl_toolkits.mplot3d import Axes3D
from mpl_toolkits.mplot3d.axis3d import Axis

# function which applies monkey patching
def _remove_margins():
    """
    Removes margins about z=0 and improves the style
    """
    if not hasattr(Axis, "_get_coord_info_old"):
        def _get_coord_info_new(self, renderer):
            mins, maxs, centers, deltas, tc, highs = \
                self._get_coord_info_old(renderer)
            mins += deltas/4
            maxs -= deltas/4
            return mins, maxs, centers, deltas, tc, highs
        Axis._get_coord_info_old = Axis._get_coord_info
        Axis._get_coord_info = _get_coord_info_new


# function which visualizes the matrix
# ✅ this function should be affected by monkey patching
def visualize_matrix(M, figsize, ... ):
    _remove_margins()
    
    fig = plt.figure(figsize=figsize)
    ax  = Axes3D(fig)
    ax.bar3d(...)
    .
    .
    .
    return fig, ax

# another function that uses Axes3D
# ⛔️ this function should not be affected by monkey patching
def visualize_sphere(...):
    fig = plt.figure(figsize=figsize)
    ax  = Axes3D(fig)
    .
    .
    .
    return fig, ax

问题：

在 Axes3D 的未来调用中（例如使用 visualize_sphere 函数），由 monkey patching 所做的更改仍然存在。

问题：

如何通过monkey patch安全解决问题？

Answer 1

我更改了 monkey 补丁以仅对实例进行更改，而不是 class。在创建 ax.

后，将 patch_axis 应用于 ax.xaxis、ax.yaxis 和 ax.zaxis

import matplotlib.pyplot as plt
import numpy as np


def patch_axis(axis):
    def _get_coord_info_new(renderer):
        mins, maxs, centers, deltas, tc, highs = _get_coord_info_old(renderer)
        mins += deltas / 4
        maxs -= deltas / 4
        return mins, maxs, centers, deltas, tc, highs

    _get_coord_info_old = axis._get_coord_info
    axis._get_coord_info = _get_coord_info_new


def test():
    fig = plt.figure()
    ax = fig.add_subplot(111, projection='3d')
    ax.margins(0)
    for c, z in zip(['r', 'g', 'b', 'y'], [30, 20, 10, 0]):
        xs = np.arange(20)
        ys = np.random.rand(20)

        # You can provide either a single color or an array. To demonstrate this,
        # the first bar of each set will be colored cyan.
        cs = [c] * len(xs)
        cs[0] = 'c'
        ax.bar(xs, ys, zs=z, zdir='y', color=cs, alpha=0.8)

    ax.set_xlabel('X')
    ax.set_ylabel('Y')
    ax.set_zlabel('Z')

    return fig, ax

# without the margin
fig, ax = test()
patch_axis(ax.xaxis)
patch_axis(ax.yaxis)
patch_axis(ax.zaxis)
fig.savefig("test1.png")

# with the margin
fig, ax = test()
fig.savefig("test2.png")

方法只是在classes的命名空间中定义的函数，访问实例方法隐式填充自身参数（见Class instances in https://docs.python.org/3/reference/datamodel.html）。您可以通过在实例化添加的命名空间中分配不带自参数的函数来覆盖 bound method。

>>> class C:
...     def f(self): return 1
... 
>>> C.f
<function C.f at 0x7f36a7eb53a0>
>>> c = C()
>>> c.f
<bound method C.f of <__main__.C object at 0x7f36a7f48eb0>>
>>> c.f()
1
>>> c.f = lambda: 2
>>> c.f()
2

如何安全地修补 matplotlib 的轴（不影响以后的调用）？

How to monkey patch matplotlib's axis safely (Not affecting future calls)?

python

monkeypatching

function

with-statement

问题：

问题：