Boids.py输出不显示动态图？只有一张空白的figure1: 左下角有configure subplot等图标可点击调整空间大小。

Question

问题：Boids.py运行结果为啥不显示动图？只有一张空白的figure（左下角有configure subplot子标签）.
谢谢！

Python版本与Pycharm: python 3.10.0. PyCharm 2021.
Boids.py如下：

"""
boids.py 

Implementation of Craig Reynold's BOIDs

Author: Mahesh Venkitachalam
"""

import sys, argparse
import math
import numpy as np
import matplotlib.pyplot as plt
import matplotlib.animation as animation
import scipy
from scipy.spatial.distance import squareform, pdist, cdist
from numpy.linalg import norm

width, height = 640, 480

class Boids:
    """Class that represents Boids simulation"""
    def __init__(self, N):
        """ initialize the Boid simulation"""
        # init position & velocities
        self.pos = [width / 2.0, height / 2.0] + 10 * np.random.rand(2 * N).reshape(N, 2)
        # normalized random velocities
        angles = 2 * math.pi * np.random.rand(N)
        self.vel = np.array(list(zip(np.sin(angles), np.cos(angles))))
        self.N = N
        # min dist of approach
        self.minDist = 25.0
        # max magnitude of velocities calculated by "rules"
        self.maxRuleVel = 0.03
        # max maginitude of final velocity
        self.maxVel = 2.0

    def tick(self, frameNum, pts, beak):
        """Update the simulation by one time step."""
        # get pairwise distances
        self.distMatrix = squareform(pdist(self.pos))
        # apply rules:
        self.vel += self.applyRules()
        self.limit(self.vel, self.maxVel)
        self.pos += self.vel
        self.applyBC()
        # update data
        pts.set_data(self.pos.reshape(2 * self.N)[::2],
                     self.pos.reshape(2 * self.N)[1::2])
        vec = self.pos + 10 * self.vel / self.maxVel
        beak.set_data(vec.reshape(2 * self.N)[::2],
                      vec.reshape(2 * self.N)[1::2])

    def limitVec(self, vec, maxVal):
        """limit magnitide of 2D vector"""
        mag = norm(vec)
        if mag > maxVal:
            vec[0], vec[1] = vec[0] * maxVal / mag, vec[1] * maxVal / mag

    def limit(self, X, maxVal):
        """limit magnitide of 2D vectors in array X to maxValue"""
        for vec in X:
            self.limitVec(vec, maxVal)

    def applyBC(self):
        """apply boundary conditions"""
        deltaR = 2.0
        for coord in self.pos:
            if coord[0] > width + deltaR:
                coord[0] = - deltaR
            if coord[0] < - deltaR:
                coord[0] = width + deltaR
            if coord[1] > height + deltaR:
                coord[1] = - deltaR
            if coord[1] < - deltaR:
                coord[1] = height + deltaR

    def applyRules(self):
        # apply rule #1 - Separation
        D = self.distMatrix < 25.0
        vel = self.pos * D.sum(axis=1).reshape(self.N, 1) - D.dot(self.pos)
        self.limit(vel, self.maxRuleVel)

        # different distance threshold
        D = self.distMatrix < 50.0

        # apply rule #2 - Alignment
        vel2 = D.dot(self.vel)
        self.limit(vel2, self.maxRuleVel)
        vel += vel2;

        # apply rule #1 - Cohesion
        vel3 = D.dot(self.pos) - self.pos
        self.limit(vel3, self.maxRuleVel)
        vel += vel3

        return vel

    def buttonPress(self, event):
        """event handler for matplotlib button presses"""
        # left click - add a boid
        if event.button == 1:
            self.pos = np.concatenate((self.pos,
                                       np.array([[event.xdata, event.ydata]])),
                                      axis=0)
            # random velocity
            angles = 2 * math.pi * np.random.rand(1)
            v = np.array(list(zip(np.sin(angles), np.cos(angles))))
            self.vel = np.concatenate((self.vel, v), axis=0)
            self.N += 1
            # right click - scatter
        elif event.button == 3:
            # add scattering velocity
            self.vel += 0.1 * (self.pos - np.array([[event.xdata, event.ydata]]))


def tick(frameNum, pts, beak, boids):
    # print frameNum
    """update function for animation"""
    boids.tick(frameNum, pts, beak)
    return pts, beak


# main() function
def main():
    # use sys.argv if needed
    print('starting boids...')

    parser = argparse.ArgumentParser(description="Implementing Craig Reynold's Boids...")
    # add arguments
    parser.add_argument('--num-boids', dest='N', required=False)
    args = parser.parse_args(args=[])

    # number of boids
    N = 100
    if args.N:
        N = int(args.N)

    # create boids
    boids = Boids(N)

    # setup plot
    fig = plt.figure()
    ax = plt.axes(xlim=(0, width), ylim=(0, height))

    pts, = ax.plot([], [], markersize=10,
                   c='k', marker='o', ls='None')
    beak, = ax.plot([], [], markersize=4,
                    c='r', marker='o', ls='None')
    anim = animation.FuncAnimation(fig, tick, fargs=(pts, beak, boids),
                                   interval=50)

    # add a "button press" event handler
    cid = fig.canvas.mpl_connect('button_press_event', boids.buttonPress)

    plt.show()

# call main
if __name__ == '__main__':
    main()

输出提示： C:...\site-packages\matplotlib\animation.py:889: UserWarning: Animation was deleted without rendering anything. This is most likely not intended. To prevent deletion, assign the Animation to a variable, e.g. anim, that exists until you have outputted the Animation using plt.show() or anim.save().
warnings.warn(
说明：输出确实显示的warn后只有左括号。

解决思路：无从下手。

目的：显示动态图。

谢谢！

Answer 1

我将你的代码运行了一下，是可以显示出来的。