python - Matplotlib - MatplotlibDeprecationWarning

Question

我制作了一个程序，它进行随机游走并绘制它。它运行良好，但每次运行程序时我都会收到警告。它说:

MatplotlibDeprecationWarning: 
Adding an axes using the same arguments as a previous axes currently reuses the earlier instance.  
In a future version, a new instance will always be created and returned.  Meanwhile, this warning can be suppressed,
and the future behavior ensured, by passing a unique label to each axes instance.

当我尝试删除 rw_visual.py 中的 x 和 y 轴时，警告警告我

我的 random_walk.py (如果你需要测试它):

from random import choice

class RandomWalk():
    """A class to generate random walks."""

    def __init__(self, num_points=5000):
        """Initialize attributes of a walk."""
        self.num_points = num_points

        # All walks start at (0, 0).
        self.x_values = [0]
        self.y_values = [0]

    def fill_walk(self):
        """Calculate all the points in the walk."""

        # Keep taking steps until the walk reaches the desired length.
        while len(self.x_values) < self.num_points:

            # Decide which direction to go and how far to go in that direction.
            x_direction = choice([1, -1])
            x_distance = choice([0, 1, 2, 3, 4])
            x_step = x_direction * x_distance

            y_direction = choice([1, -1])
            y_distance = choice([0, 1, 2, 3, 4])
            y_step = y_direction * y_distance

            # Reject moves that go nowhere.
            if x_step == 0 and y_step == 0:
                continue

            # Calculate the next x and y values.
            next_x = self.x_values[-1] + x_step
            next_y = self.y_values[-1] + y_step

            self.x_values.append(next_x)
            self.y_values.append(next_y)

我的 rw_visual.py (发生警告的地方):

import matplotlib.pyplot as plt

from random_walk import RandomWalk

# Keep making new walks, as long as the program is active.
while True:
    # Make random walk, and plot the points.
    rw = RandomWalk()
    rw.fill_walk()

    point_numbers = list(range(rw.num_points))
    plt.scatter(rw.x_values, rw.y_values, c=point_numbers, cmap=plt.cm.Blues,
                edgecolor='none', s=10)

    # Emphasize the first and last points.
    plt.scatter(0, 0, c='green', edgecolors='none', s=150)
    plt.scatter(rw.x_values[-1], rw.y_values[-1], c='red', edgecolors='none',
                s=150)

    # Remove the axes.
    plt.axes().get_xaxis().set_visible(False) # This is what it warns me about, I think.
    plt.axes().get_yaxis().set_visible(False) # It also warns me about this.
    plt.show()

    keep_running = input("Make another walk? (y/n): ")
    if keep_running == 'n':
        break

任何帮助表示赞赏。谢谢!

Answer 1

plt.axes()激活已经创建的轴(这是在您执行 plt.scatter 时创建的)。警告告诉您，在 future 的版本中，它不会激活已经创建的轴，而是创建一个新的轴实例。

您可能想要的是获取当前正在使用的轴。您可以使用 plt.gca() 轻松完成此操作.

所以更换

plt.axes().get_xaxis().set_visible(False) 
plt.axes().get_yaxis().set_visible(False) 

和

plt.gca().get_xaxis().set_visible(False)
plt.gca().get_yaxis().set_visible(False)