Python 2.7 AttributeError:draw\u Artister只能在缓存渲染的初始绘制之后使用

我的要求是在极坐标图中绘制数据。然而，我需要保持极坐标图在特定角度看起来像“V”形，数据需要在特定角度之间绘制

在python中，我没有找到一种解决方案来保持极坐标图的特定角度，例如：图应该显示在-60到60度半径之间。为了实现这一点，我研究了两个现有示例，并使用FloatingSubplot函数创建了所需的极坐标图。但是，当我们尝试使用函数animation function with blit=True时，我遇到了这个问题。显示的错误消息为“AttributeError:draw\u Artister只能在缓存渲染的初始绘制之后使用”

这是我的密码

import matplotlib
matplotlib.use('Qt4Agg')
import numpy as np
import matplotlib.pyplot as plt
from matplotlib import style
import matplotlib.animation as animation
import mpl_toolkits.axisartist.floating_axes as floating_axes
from matplotlib.transforms import Affine2D
from matplotlib.projections import PolarAxes
from mpl_toolkits.axisartist import angle_helper
from mpl_toolkits.axisartist.grid_finder import MaxNLocator, DictFormatter
from mpl_toolkits.axisartist.floating_axes import GridHelperCurveLinear, FloatingSubplot

plt.close('all')

fig = plt.figure('Practice', dpi=100)  # To set the fig title as pratice

ax1 = fig.add_subplot(2, 2, 1)  # subplot for 1st plot
plt.ion()
ax1.grid(True)


def fractional_polar_axes(f, thlim=(0, 120), rlim=(0, 20), step=(30, 0.25),
                          thlabel='theta', rlabel='r', ticklabels=True, theta_offset=0, rlabels=None):
    '''Return polar axes that adhere to desired theta (in deg) and r limits. steps for theta
and r are really just hints for the locators.'''
    th0, th1 = thlim  # deg
    r0, r1 = rlim
    thstep, rstep = step

    tr_rotate = Affine2D().translate(theta_offset, 0)
    # scale degrees to radians:
    tr_scale = Affine2D().scale(np.pi / 180., 1.)
    # pa = axes(polar="true") # Create a polar axis
    pa = PolarAxes
    tr = tr_rotate + tr_scale + pa.PolarTransform()
    theta_grid_locator = angle_helper.LocatorDMS((th1 - th0) // thstep)
    r_grid_locator = MaxNLocator((r1 - r0) // rstep)
    theta_tick_formatter = angle_helper.FormatterDMS()
    if rlabels:
        rlabels = DictFormatter(rlabels)

    grid_helper = GridHelperCurveLinear(tr,
                                        extremes=(th0, th1, r0, r1),
                                        grid_locator1=theta_grid_locator,
                                        grid_locator2=r_grid_locator,
                                        tick_formatter1=theta_tick_formatter,
                                        tick_formatter2=rlabels)

    a = FloatingSubplot(f, 222, grid_helper=grid_helper)
    # a = Subplot(f,753, grid_helper=grid_helper)
    # f.add_subplot(7,5,(3,34))
    f.add_subplot(a)
    # adjust x axis (theta):
    print(a)
    a.axis["bottom"].set_visible(False)
    a.axis["top"].set_axis_direction("bottom")  # tick direction
    a.axis["top"].toggle(ticklabels=ticklabels, label=bool(thlabel))
    a.axis["top"].major_ticklabels.set_axis_direction("top")
    a.axis["top"].label.set_axis_direction("top")
    a.axis["top"].major_ticklabels.set_pad(10)

    # adjust y axis (r):
    a.axis["left"].set_axis_direction("bottom")  # tick direction
    a.axis["right"].set_axis_direction("top")  # tick direction
    a.axis["left"].toggle(ticklabels=True, label=bool(rlabel))
    # add labels:
    a.axis["top"].label.set_text(thlabel)
    a.axis["left"].label.set_text(rlabel)
    # create a parasite axes whose transData is theta, r:
    auxa = a.get_aux_axes(tr)
    print(auxa)
    # make aux_ax to have a clip path as in a?:
    auxa.patch = a.patch
    # this has a side effect that the patch is drawn twice, and possibly over some other
    # artists. So, we decrease the zorder a bit to prevent this:
    a.patch.zorder = -2

    # add sector lines for both dimensions:
    thticks = grid_helper.grid_info['lon_info'][0]
    rticks = grid_helper.grid_info['lat_info'][0]
    print(grid_helper.grid_info['lat_info'])
    for th in thticks[1:-1]:  # all but the first and last
        auxa.plot([th, th], [r0, r1], ':', c='grey', zorder=-1, lw=0.5)
    for ri, r in enumerate(rticks):
        # plot first r line as axes border in solid black only if it  isn't at r=0
        if ri == 0 and r != 0:
            ls, lw, color = 'solid', 1, 'black'
        else:
            ls, lw, color = 'dashed', 0.5, 'grey'
        # From http://stackoverflow.com/a/19828753/2020363
        auxa.add_artist(plt.Circle([0, 0], radius=r, ls=ls, lw=lw, color=color, fill=False,
                                   transform=auxa.transData._b, zorder=-1))

    return auxa

def animate(i):
    global loopcount, th, r
    th = th+.1
    r = r+.1

    datapoints.set_offsets(np.vstack((th,r)).T)
    #print("in animate")
    return datapoints,


if __name__ == '__main__':
    r_locs = [0,5,10, 15, 20]

    r_labels = ['0', '5', '10', '15', '20']
    r_ticks = {loc: label for loc, label in zip(r_locs, r_labels)}
    a1 = fractional_polar_axes(fig, thlim=(-60, 60), step=(20, 5),
                               theta_offset=90, rlabels=r_ticks)
    th= 20
    r=10
    a1.scatter(th,r , c = 'r', alpha = 0.5, linewidths = '.2', s = 20) # plotting the line at thetha 20 and radius 10
    datapoints = a1.scatter([], [], c='b',  alpha = 0.5, linewidths = '.2', s = 20) # creating scatter line with given instruction,
    ani = animation.FuncAnimation(fig, animate, frames=30, interval=20, blit=True)

plt.show(block=True)

# # “”“ 上述代码在blit=False时运行良好，同样的解决方案在正常图形中的直线和散点绘图时运行良好。
请有人帮我解决这个问题。

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“

浮动子图很有可能不允许闪电。感谢您的快速响应，有没有其他方法解决我的问题？我不知道。我会选择不使用blitting。