如何在Python动画函数中返回未知数量的对象 [英] How to return an unknown number of objects in Python animation function

问题描述

我目前正在尝试制作一系列图像的动画，其中为每个图像绘制一个最初未知的椭圆形。到目前为止，我已经尝试了很多方法，但是还没有找到解决方案，尽管我想我已经接近了。这是我的代码：

I am currently trying to animate a series of images where for each image an initially unknown number of ellipses are drawn. I have tried many things so far, but haven't found a solution yet, though I guess I came close. Here is my code:

import matplotlib.pyplot as plt
from matplotlib.patches import Ellipse

def plot_images(img1, img2, objects, ax):

    im1 = ax.imshow(img1)
    im2 = ax.imshow(img2 with transparency as an overlay)

    # plotting an ellipse for each object
    e = [None]*len(objects)
    for j in range(len(objects)):
        e[j] = Ellipse(xy=(objects['x'][j], objects['y'][j]),
                            width=6 * objects['a'][j],
                            height=6 * objects['b'][j],
                            angle=objects['theta'][j] * 180. / np.pi)
        e[j].set_facecolor('none')
        e[j].set_edgecolor('red')
        ax.add_artist(e[j])

    return im1, im2, e


def animate(j):

    # extracting objects
    im1, im2, objects = object_finder_function()

    imm1, imm2, e = plot_images(im1, im2, objects, axs)


    return imm1, imm2, e

fig, axs = plt.subplots()
ani = animation.FuncAnimation(fig, animate, frames=image_number, interval=50, blit=True)
plt.show()

现在当我尝试时这段代码，我得到以下错误消息：

Now when I try this code, I get the following error message:

AttributeError: 'list' object has no attribute 'get_zorder'

所以我尝试了不同的方法，但最终，我发现，当作为测试时，我将plot_images函数放入

So I tried different things, but ultimately, I found that when, as a test, I put in the plot_images function

return im1, im2, e[0], e[1], e[2]

，并相应地更改动画功能，即

and also change the animate function accordingly, i.e.

imm1, imm2, e0, e1, e2 = plot_images(im1, im2, objects, axs)

和

return imm1, imm2, e0, e1, e2

我没有收到错误消息，实际上按照我的意图在各个帧中绘制了椭圆。现在的问题是，对于一个图像，我想绘制每幅图像有数百个椭圆，所以我必须手动将其全部写下（即e [0]，e [1]，e [2]- -e [k]，和动画功能相同），这似乎不是正确的方法。另一件事是，正如我已经说过的，每张图像的椭圆数会发生变化，并且以前是未知的，因此我无法相应地调整功能。

I don't get an error message and the ellipses are actually plotted in the respective frames as I intended. Now the problem is, that for one, there are many hundred ellipses per image that I would like to plot, so I would have to manually write that all down (i.e. e[0], e[1], e[2] -- e[k], and the same for the animate function) and this doesn't seem to be the right way. The other thing is that as I already said the number of ellipses changes for each image and is not previously known so I cannot possibly adjust the functions accordingly.

如何返回此椭圆列表，以便动画读取它，就像我会像在工作示例中一样将它们全部写下来一样？

How can I return this list of ellipses so that the animation reads it as if I would have written them all down separately as it is done in the working example?

推荐答案

您的代码有点不合逻辑，因此为了清晰起见，我对其进行了一些清理。您的 AttributeError 与 get_zorder 函数有关，该函数在matplotlib中用于确定如何对绘图进行分层。使用您尝试过的方法，我可以告诉您只需要最后打开list_of_ellipses即可。

Your code is a bit unpythonic, so I cleaned up it just a bit for clarity. Your AttributeError has to do with the get_zorder function, which is used in matplotlib for figuring out how to layer plots. With the things you tried I can tell you just need to unpack your list_of_ellipses at the end.

def plot_images(img1, img2, objects, ax):

    im1 = ax.imshow(img1)
    im2 = ax.imshow(img2 with transparency as an overlay)

    list_of_ellipses = []
    for j in range(len(objects)):
        my_ellipse = Ellipse(xy=(objects['x'][j], objects['y'][j]),
                        width=6 * objects['a'][j],
                        height=6 * objects['b'][j],
                        angle=objects['theta'][j] * 180. / np.pi)

        my_ellipse.set_facecolor('none')
        my_ellipse.set_edgecolor('red')
        ax.add_artist(my_ellipse)
        list_of_ellipses.append(my_ellipse)
    return im1, im2, list_of_ellipses


def animate():
    im1, im2, objects = object_finder_function()
    imm1, imm2, list_of_ellipses = plot_images(im1, im2, objects, axs)
    return (imm1, imm2)+tuple(list_of_ellipses)

fig, axs = plt.subplots()
ani = animation.FuncAnimation(fig, animate, frames=image_number, interval=50, blit=True)
plt.show()

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