通过pygame库,模拟种群的分化
1.X从左往右移动,表示年龄的增加;Y坐标表示阶层
2.随着X坐标不断增大,圆逐渐增大,颜色也加深
3.精灵越多,碰撞后死亡的概率越大,诞生新精灵的概率越小
4.每个精灵都有随机的运动速度及Y坐标的移动方向
5.发生碰撞且诞生新精灵时,继承当前坐标的Y值

一.效果

• 初始状态
  
• 迭代一段时间后
  

二.代码

import pygame
import numpy as np
import random

min_sprite_radius=5
max_sprite_radius=15

max_width=max_sprite_radius*100
max_height=min_sprite_radius*100
max_sprites=5000

class Life(pygame.sprite.Sprite):
    def __init__(self,y=None):
        super().__init__()
        self.image = pygame.Surface((min_sprite_radius, min_sprite_radius),pygame.SRCALPHA)
        self.rect = self.image.get_rect()
        self.rect.centerx = np.random.randint(0,max_width)
        if y:
            self.rect.centery = y
        else:
            self.rect.centery = np.random.randint(0,max_height)
    def update(self):        
        dir   = np.random.randint(-1*min_sprite_radius,min_sprite_radius)  
        speed = np.random.randint(1,min_sprite_radius)

        self.rect.centerx += speed
        self.rect.centery += dir

        ratio=self.rect.centerx/max_width

        color_depth=ratio*255
        radius =ratio*(max_sprite_radius-min_sprite_radius)+min_sprite_radius

        self.image = pygame.transform.scale(self.image, (radius , radius ))
        
        pygame.draw.circle(self.image, (color_depth, 128, 128), (radius //2, radius //2), (radius //2)-1)

random.seed(2)
np.random.seed(2)

pygame.init()
screen = pygame.display.set_mode((max_width,max_height))
pygame.display.update()

clock = pygame.time.Clock()
fps=30

sprite_group = pygame.sprite.Group(*[Life() for _ in range(max_sprites//10)])

while True:
    clock.tick(fps)
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            print("退出...")
            pygame.quit()
            exit()

    screen.fill((31, 31, 31))
    
    sprite_group.update()

    # 判断是否超出边界
    for group_a_sprite in sprite_group.sprites():
        bkill=False
        if group_a_sprite.rect.centerx>=max_width:
            bkill=True
        if group_a_sprite.rect.centery>=max_height or group_a_sprite.rect.centery<0:
            bkill=True
        if bkill:
            group_a_sprite.kill()

    # 碰撞检测
    add_yoffsets=[]
    total_sprites=len(sprite_group)
    for group_a_sprite in sprite_group.sprites():
        collision = pygame.sprite.spritecollide(group_a_sprite, sprite_group, False)
        for j in collision:
            if id(group_a_sprite)==id(j):
                continue
            else:
                kill_prob=total_sprites/max_sprites
                remain_prob=1.0-kill_prob
                state=random.choices([0,1,2],[kill_prob,remain_prob/2,remain_prob/2],k=1)[0]
                if state==0:
                    group_a_sprite.kill()
                if state==1:
                    add_yoffsets.append(group_a_sprite.rect.centery)
                if state==2:
                    pass
    
    # 生成新精灵
    if total_sprites<max_sprites:
        for y in add_yoffsets:
            sprite_group.add(Life(y))

    sprite_group.draw(screen)

    myString=f"count:{total_sprites}"
    font = pygame.font.SysFont("Times New Roman", 48)
    text = font.render(myString, True, (255,255,255))
    screen.blit(text, (10,10))
    pygame.display.update()

pygame.quit()