如何在鼠標懸停事件發生時更改扇區的顏色

Question

我在matplotlib中創建了一個餅圖。我想實現this結果python 即每當鼠標懸停在任何切片的顏色發生變化。我搜索了很多，想出了使用bind方法，但這並不是有效的，因此無法拿出積極的結果。如果這可以通過任何其他庫（例如tkinter，plotly等，但我需要與matplotlib想出解決方案，所以我希望更多），我會沒有問題。請看看我的問題和任何建議是熱烈歡迎... 這裏是我的代碼：

import matplotlib.pyplot as plt 

labels = 'A', 'B', 'C', 'D' 
sizes = [10, 35, 50, 5] 
explode = (0, 0, 0.1, 0) # only "explode" the 3rd slice (i.e. 'C') 

fig1, ax1 = plt.subplots() 
ax1.pie(sizes, explode=explode, labels=labels, autopct='%1.1f%%', 
    shadow=True, startangle=90) 
ax1.axis('equal') # Equal aspect ratio ensures that pie is drawn as a circle. 

plt.show() 

問候......

Answer 1

你會需要一個motion_notify_event一個matplotlib event handler。 這可以連接到一個函數，該函數檢查鼠標是否在餅圖的楔形內。這通過contains_point完成。在這種情況下，以不同的方式着色楔塊，否則將其顏色設置爲其原始顏色。

import matplotlib.pyplot as plt 

labels = 'A', 'B', 'C', 'D' 
sizes = [10, 35, 50, 5] 
explode = (0, 0, 0.1, 0) # only "explode" the 3rd slice (i.e. 'C') 

fig1, ax1 = plt.subplots() 
wedges, _, __ = ax1.pie(sizes, explode=explode, labels=labels, autopct='%1.1f%%', 
    shadow=True, startangle=90) 
ax1.axis('equal') # Equal aspect ratio ensures that pie is drawn as a circle. 

ocols= [w.get_facecolor() for w in wedges] 
ncols= ["gold", "indigo", "purple", "salmon"] 

def update(event): 
    if event.inaxes == ax1: 
     for i, w in enumerate(wedges): 
      if w.contains_point([event.x, event.y]): 
       w.set_facecolor(ncols[i]) 
      else: 
       w.set_facecolor(ocols[i]) 
     fig1.canvas.draw_idle() 


fig1.canvas.mpl_connect("motion_notify_event", update) 

plt.show() 

Answer 2

首先，你要找的是the documentation on Event handling in matplotlib。特別是，每當鼠標移動時，都會觸發motion_notify_event。不過，我想不出一個簡單的方法來確定鼠標哪個楔子現在結束。

如果點擊是可以接受的，那麼問題就容易得多：

labels = 'A', 'B', 'C', 'D' 
sizes = [10, 35, 50, 5] 
explode = (0, 0, 0.1, 0) # only "explode" the 3rd slice (i.e. 'C') 
click_color = [0.2, 0.2, 0.2] 

fig1, ax1 = plt.subplots() 
patches, texts, autotexts = ax1.pie(sizes, explode=explode, labels=labels, autopct='%1.1f%%', 
    shadow=True, startangle=90) 

# store original color inside patch object 
# THIS IS VERY HACKY. 
# We use the Artist's 'gid' which seems to be unused as far as I can tell 
# to be able to recall the original color 
for p in patches: 
    p.set_gid(p.get_facecolor()) 
    # enable picking 
    p.set_picker(True) 

ax1.axis('equal') # Equal aspect ratio ensures that pie is drawn as a circle. 


def on_pick(event): 
    #restore all facescolor to erase previous changes 
    for p in patches: 
     p.set_facecolor(p.get_gid()) 
    a = event.artist 
    # print('on pick:', a, a.get_gid()) 
    a.set_facecolor(click_color) 
    plt.draw() 

fig1.canvas.mpl_connect('pick_event', on_pick) 
plt.show()