Python matplotlib - 在康威的生命游戏中更新数据答案

【问题标题】：Python matplotlib - updating data during animation in Conway's Game of LifePython matplotlib - 在康威的生命游戏中更新数据
【发布时间】：2013-06-21 18:47:26
【问题描述】：

下面的代码使用 Python 和 matplotlib 为康威的生命游戏创建动画。

我不知道为什么我必须这样做：

grid = newGrid.copy()
mat.set_data(grid)

而不是简单地：

mat.set_data(newGrid)

如何在不进行上述复制的情况下更新与绘图关联的数组？

import numpy as np
import matplotlib.pyplot as plt 
import matplotlib.animation as animation

N = 100
ON = 255
OFF = 0
vals = [ON, OFF]

# populate grid with random on/off - more off than on
grid = np.random.choice(vals, N*N, p=[0.2, 0.8]).reshape(N, N)

def update(data):
  global grid
  newGrid = grid.copy()
  for i in range(N):
    for j in range(N):
      total = (grid[i, (j-1)%N] + grid[i, (j+1)%N] + 
               grid[(i-1)%N, j] + grid[(i+1)%N, j] + 
               grid[(i-1)%N, (j-1)%N] + grid[(i-1)%N, (j+1)%N] + 
               grid[(i+1)%N, (j-1)%N] + grid[(i+1)%N, (j+1)%N])/255

      if grid[i, j]  == ON:
        if (total < 2) or (total > 3):
          newGrid[i, j] = OFF
      else:
        if total == 3:
          newGrid[i, j] = ON

  grid = newGrid.copy()
  mat.set_data(grid)
  return mat 

fig, ax = plt.subplots()
mat = ax.matshow(grid)
ani = animation.FuncAnimation(fig, update, interval=50,
                              save_count=50)
plt.show()

输出似乎正确 - 我可以看到滑翔机和其他预期模式：

【问题讨论】：

标签： python matplotlib

【解决方案1】：

mat.set_data() 需要 newGrid 的副本并没有什么特别的原因 - 重要的是全局 grid 会随着迭代而更新：

def update(data):
  global grid
  newGrid = grid.copy()

  """
  do your updating. this needs to be done on a copy of 'grid' because you are
  updating element-by-element, and updates to previous rows/columns will
  affect the result at 'grid[i,j]' if you don't use a copy
  """

  # you do need to update the global 'grid' otherwise the simulation will
  # not progress, but there's no need to copy()
  mat.set_data(newGrid)
  grid = newGrid

  # # there's no reason why you couldn't do it in the opposite order
  # grid = newGrid
  # mat.set_data(grid)

  # at least in my version of matplotlib (1.2.1), the animation function must
  # return an iterable containing the updated artists, i.e. 'mat,' or '[mat]',
  # not 'mat'
  return [mat]

另外，我建议在FuncAnimation 中传递blit=True，这样您就不会在每一帧上都重绘背景。

【讨论】：