Matplotlib在第一帧后停止动画

Question

我正在尝试为两个子图设置动画,每个子图有多行.我正在使用Matplotlib,我使用的FuncAnimation是许多动画示例所使用的.

使用动画:

如果我尝试动画它,我只得到第一帧的结果:

不使用动画:

如果我手动调用我的update_lines函数,它工作正常.

码:

下面是完整的代码(在main()工作中取消注释3个指示的行,但我希望看到它实时更新,因此尝试使用动画).

import matplotlib.pyplot as plt
from matplotlib.animation import FuncAnimation


def make_subplots():
    def setup_axes(axes):
        for ax in axes:
            ax.set_xbound(0, 100)  # bound will change as needed.
            ax.set_ylim(0, 1)  # limit won't change automatically.

    def make_lines(axes):
        labels = ('a', 'b', 'c')
        lines = []
        for ax in axes:
            ax_lines = []
            for label in labels:
                x, y = [0], [0]
                line, = ax.plot(x, y, label=label)  # comma for unpacking.
                ax_lines.append((line, x, y))
            lines.append(ax_lines)
        return lines

    fig, axes = plt.subplots(2, 1, sharex=True, sharey=True)
    lines = make_lines(axes)
    setup_axes(axes)
    return fig, axes, lines


def make_data():
    for i in xrange(100):
        print 'make_data():', i
        data = dict()
        for label in ('a', 'b', 'c'):
            from random import random
            data[label] = random()
        yield (i + 1, data)


def update_lines(data, lines):
    print 'update_lines():', data, lines
    updated_lines = []
    for ax_lines in lines:
        for line, x, y in ax_lines:
            label = line.get_label()
            x.append(data[0])
            y.append(data[1][label])
            line.set_data(x, y)
            updated_lines.append(line)


def main():
    fig, axes, lines = make_subplots()

    # Uncomment these 3 lines, and it works!
    # new_data = make_data()
    # for data in new_data:
    #     update_lines(data, lines)

    FuncAnimation(fig=fig,
                  func=update_lines,
                  frames=make_data,
                  fargs=(lines,),
                  interval=10,
                  blit=False)

    plt.show()


if __name__ == '__main__':
    main()

Answer 1

(没有证件？)钩子

所以,我正在挖掘源代码matplotlib.animation.Animation,我注意到__init__()函数中的这些行:

# Clear the initial frame
self._init_draw()

# Instead of starting the event source now, we connect to the figure's
# draw_event, so that we only start once the figure has been drawn.
self._first_draw_id = fig.canvas.mpl_connect('draw_event', self._start)

听起来很熟悉...

这看起来是正确的.该self._init_draw()呼叫立即绘制了我的第一帧.然后动画对象挂钩到图形对象中,等待图形显示,然后再尝试为动画绘制更多帧.

找到了!

关键字是:animation- object.由于我之前没有计划使用动画实例(例如,绘制电影),我没有将它分配给变量.事实上,我被大声呵斥由pyflakes因Local variable '...' is assigned to but never used.

但是因为所有的功能都依赖于钩子,所以当画布最终显示时,我认为Python的垃圾收集已经移除了动画实例---因为它从未被分配给变量---因此动画永远无法启动.

修复

只需将实例FuncAnimation实例分配给变量,一切都按预期工作!

anim = FuncAnimation(fig=fig,
                     func=update_lines,
                     frames=make_data,
                     fargs=(lines,),
                     interval=10,
                     blit=False)