matplotlib中的動畫標題

Question

我無法弄清楚如何在FuncAnimation情節（使用blit）上獲得動畫標題。基於http://jakevdp.github.io/blog/2012/08/18/matplotlib-animation-tutorial/和Python/Matplotlib - Quickly Updating Text on Axes，我已經構建了一個動畫，但文本部分不會動畫。簡單的例子：

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被刪除，文本顯示出來，但它減緩一路下滑。它似乎失敗，plt.title,ax.set_title和ax.text。

編輯：我發現爲什麼第一個鏈接的第二個例子工作;該文本在img部分。如果你使上述1.005 a .99，你會明白我的意思。有可能是一種方式具有邊框，不知何故做到這一點...

Answer 1

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

那麼，問題是，在該塊傳輸的背景實際上是保存（行animation.py 792）的animation膽量，它抓住的是在軸邊界框。當您有多個獨立動畫的軸時，這是有意義的。在你的情況下，你只有一個axes擔心，我們想要動畫的動畫軸邊界框外。帶着幾分猴子修補，公差爲伸進MPL的膽量和周圍有點戳的水平，並接受最快，dirtyest解決方案，我們可以解決你的問題，因爲這樣的：

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，這如果圖中有多個軸，則可能無法按預期工作。一個更好的解決方案是擴展axes.bbox只需足以捕獲您的標題+軸刻度標籤。我懷疑在mpl中有代碼可以做到這一點，但我不知道它在哪裏。

Answer 2

必須調用

plt.draw() 

後

ttl.set_text(str(n)) 

---

在這裏有一個很簡單的例子沒有FuncAnimation（）「的圖形內的文本動畫」。嘗試一下，你會看到它是否對你有用。

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「猴子修補」解決方案，以下是如何將動畫添加到軸刻度標籤。具體來說，要動畫x軸，請設置ax.xaxis.set_animated(True)並從動畫函數返回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

如果您需要修復的標題，你可以只更新標題：

fig.suptitle() 

參見圖API document。