matplotlib中的动画标题

Question

我无法弄清楚如何在FuncAnimation情节（使用blit）上获得动画标题。基于http://jakevdp.github.io/blog/2012/08/18/matplotlib-animation-tutorial/和Python/Matplotlib - Quickly Updating Text on Axes，我已经构建了一个动画，但文本部分不会动画。简单的例子：

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

vls = np.linspace(0,2*2*np.pi,100) 

fig=plt.figure() 
img, = plt.plot(np.sin(vls)) 
ax = plt.axes() 
ax.set_xlim([0,2*2*np.pi]) 
#ttl = ax.set_title('',animated=True) 
ttl = ax.text(.5, 1.005, '', transform = ax.transAxes) 

def init(): 
    ttl.set_text('') 
    img.set_data([0],[0]) 
    return img, ttl 
def func(n): 
    ttl.set_text(str(n)) 
    img.set_data(vls,np.sin(vls+.02*n*2*np.pi)) 
    return img, ttl 

ani = animation.FuncAnimation(fig,func,init_func=init,frames=50,interval=30,blit=True) 

plt.show() 

如果blit=True被删除，文本显示出来，但它减缓一路下滑。它似乎失败，plt.title,ax.set_title和ax.text。

编辑：我发现为什么第一个链接的第二个例子工作;该文本在img部分。如果你使上述1.005 a .99，你会明白我的意思。有可能是一种方式具有边框，不知何故做到这一点...

Answer 1

见Animating matplotlib axes/ticks和python matplotlib blit to axes or sides of the figure?

那么，问题是，在该块传输的背景实际上是保存（行animation.py 792）的animation胆量，它抓住的是在轴边界框。当您有多个独立动画的轴时，这是有意义的。在你的情况下，你只有一个axes担心，我们想要动画的动画轴边界框外。带着几分猴子修补，公差为伸进MPL的胆量和周围有点戳的水平，并接受最快，dirtyest解决方案，我们可以解决你的问题，因为这样的：

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

def _blit_draw(self, artists, bg_cache): 
    # Handles blitted drawing, which renders only the artists given instead 
    # of the entire figure. 
    updated_ax = [] 
    for a in artists: 
     # If we haven't cached the background for this axes object, do 
     # so now. This might not always be reliable, but it's an attempt 
     # to automate the process. 
     if a.axes not in bg_cache: 
      # bg_cache[a.axes] = a.figure.canvas.copy_from_bbox(a.axes.bbox) 
      # change here 
      bg_cache[a.axes] = a.figure.canvas.copy_from_bbox(a.axes.figure.bbox) 
     a.axes.draw_artist(a) 
     updated_ax.append(a.axes) 

    # After rendering all the needed artists, blit each axes individually. 
    for ax in set(updated_ax): 
     # and here 
     # ax.figure.canvas.blit(ax.bbox) 
     ax.figure.canvas.blit(ax.figure.bbox) 

# MONKEY PATCH!! 
matplotlib.animation.Animation._blit_draw = _blit_draw 

vls = np.linspace(0,2*2*np.pi,100) 

fig=plt.figure() 
img, = plt.plot(np.sin(vls)) 
ax = plt.axes() 
ax.set_xlim([0,2*2*np.pi]) 
#ttl = ax.set_title('',animated=True) 
ttl = ax.text(.5, 1.05, '', transform = ax.transAxes, va='center') 

def init(): 
    ttl.set_text('') 
    img.set_data([0],[0]) 
    return img, ttl 

def func(n): 
    ttl.set_text(str(n)) 
    img.set_data(vls,np.sin(vls+.02*n*2*np.pi)) 
    return img, ttl 

ani = animation.FuncAnimation(fig,func,init_func=init,frames=50,interval=30,blit=True) 

plt.show() 

注意，这如果图中有多个轴，则可能无法按预期工作。一个更好的解决方案是扩展axes.bbox只需足以捕获您的标题+轴刻度标签。我怀疑在mpl中有代码可以做到这一点，但我不知道它在哪里。

Answer 2

必须调用

plt.draw() 

后

ttl.set_text(str(n)) 

---

在这里有一个很简单的例子没有FuncAnimation（）“的图形内的文本动画”。尝试一下，你会看到它是否对你有用。

import matplotlib.pyplot as plt 
import numpy as np 
titles = np.arange(100) 
plt.ion() 
fig = plt.figure() 
for text in titles: 
    plt.clf() 
    fig.text(0.5,0.5,str(text)) 
    plt.draw() 

Answer 3

要添加到tcaswell的“猴子修补”解决方案，以下是如何将动画添加到轴刻度标签。具体来说，要动画x轴，请设置ax.xaxis.set_animated(True)并从动画函数返回ax.xaxis。

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

def _blit_draw(self, artists, bg_cache): 
    # Handles blitted drawing, which renders only the artists given instead 
    # of the entire figure. 
    updated_ax = [] 
    for a in artists: 
     # If we haven't cached the background for this axes object, do 
     # so now. This might not always be reliable, but it's an attempt 
     # to automate the process. 
     if a.axes not in bg_cache: 
      # bg_cache[a.axes] = a.figure.canvas.copy_from_bbox(a.axes.bbox) 
      # change here 
      bg_cache[a.axes] = a.figure.canvas.copy_from_bbox(a.axes.figure.bbox) 
     a.axes.draw_artist(a) 
     updated_ax.append(a.axes) 

    # After rendering all the needed artists, blit each axes individually. 
    for ax in set(updated_ax): 
     # and here 
     # ax.figure.canvas.blit(ax.bbox) 
     ax.figure.canvas.blit(ax.figure.bbox) 

# MONKEY PATCH!! 
matplotlib.animation.Animation._blit_draw = _blit_draw 

vls = np.linspace(0,2*2*np.pi,100) 

fig=plt.figure() 
img, = plt.plot(np.sin(vls)) 
ax = plt.axes() 
ax.set_xlim([0,2*2*np.pi]) 
#ttl = ax.set_title('',animated=True) 
ttl = ax.text(.5, 1.05, '', transform = ax.transAxes, va='center') 

ax.xaxis.set_animated(True) 

def init(): 
    ttl.set_text('') 
    img.set_data([0],[0]) 
    return img, ttl, ax.xaxis 

def func(n): 
    ttl.set_text(str(n)) 
    vls = np.linspace(0.2*n,0.2*n+2*2*np.pi,100) 
    img.set_data(vls,np.sin(vls)) 
    ax.set_xlim(vls[0],vls[-1]) 
    return img, ttl, ax.xaxis 

ani = animation.FuncAnimation(fig,func,init_func=init,frames=60,interval=200,blit=True) 

plt.show() 

Answer 4

如果您需要修复的标题，你可以只更新标题：

fig.suptitle() 

参见图API document。