Matplotlib：使用＆＃34;显示＆＃34;坐标与set_aspect（＆＃39;等于＆＃39;）

Question

我的班级（下面）有一个奇怪的问题，它会在绘制的Matplotlib线上添加刻度线。似乎当轴纵横比设置为'equal'时，显示坐标中的绘图会在交互式视图中混淆，以便＆＃34;缩放＆＃34;功能。平移和调整大小的工作正常，至少在最初校正显示之后，＃34; Home＆＃34;。 没有相等的宽高比设置就没有问题。

这是班级：

import numpy as np
from matplotlib import transforms

def get_perp_vec(u1, u2, direction=1):
    """Return the unit vector perpendicular to the vector u2-u1."""

    x1, y1 = u1
    x2, y2 = u2
    vx, vy = x2-x1, y2-y1
    v = np.linalg.norm((vx, vy))
    wx, wy = -vy/v * direction, vx/v * direction
    return wx, wy

class LineTicks:
    def __init__(self, line, idx, **kwargs):
        self.line = line
        self.ticks = []
        self.idx = idx

        self.tick_length = 20
        self.tick_styles = kwargs

        self.ax = line.axes
        self.ax.callbacks.connect('xlim_changed', self.on_change_lims)
        self.ax.callbacks.connect('ylim_changed', self.on_change_lims)
        cid = self.ax.figure.canvas.mpl_connect('resize_event',self.on_resize) 
        self.add_ticks(self.ax)

    def add_ticks(self, ax):
        ax.set_autoscale_on(False)  # Otherwise, infinite loop
        # Transform to  display coordinates
        z =ax.transData.transform(np.array(self.line.get_data()).T)
        x, y = zip(*z)

        # Remove existing ticks
        for tick in self.ticks:
            ax.lines.remove(tick)
        # Remove references to the ticks so they can be garbage-collected
        self.ticks = []

        for i in self.idx:
            tx, ty = get_perp_vec((x[i-1], y[i-1]), (x[i], y[i]))
            tx, ty = self.tick_length * tx, self.tick_length * ty
            this_tick, = ax.plot((x[i],x[i]+tx), (y[i],y[i]+ty),
                transform=transforms.IdentityTransform(), **self.tick_styles)
            self.ticks.append(this_tick)

    def on_change_lims(self, ax):
        self.add_ticks(ax)

    def on_resize(self, event):
        self.add_ticks(self.ax)

当它不起作用的时候：

import matplotlib.pyplot as plt

theta = np.arange(0, 2*np.pi, np.pi/40)
x, y = np.cos(theta), np.sin(theta)

fig, ax = plt.subplots()
ax.set_aspect('equal')
circle_line, = ax.plot(x, y)
major_ticks = LineTicks(circle_line, range(0, len(x), 10), color='r', lw=2)
plt.show()

以供参考，以及它何时运作：

x = np.arange(0, 2*np.pi, np.pi/40)
y = np.sin(x)

fig, ax = plt.subplots()
circle_line, = ax.plot(x, y)
minor_ticks = LineTicks(circle_line, range(0, len(x), 2), lw=2, color='k')
plt.show()

我对set_aspect('equal')的工作方式有什么看法，我应该怎么做？或者这是后端的错误？ [Mac OS X，Python 3.3，Matplotlib 1.4.3]