悬停在饼图上时如何显示注释并爆炸楔形？

Question

我想在饼图中添加一个事件，当悬停时，会显示一个带有值和标签的楔形的注释。经过一段时间的尝试，我得到了一个折线图的工作示例，但是对于饼图，我无法理解如何获取每个楔形的数据。到目前为止我的代码：

from matplotlib.figure import Figure

figure = Figure()
drawFigure = figure.subplots()
annotate = drawFigure.annotate("", xy=(0,0),xytext=(-20, 20), textcoords="offset points",
                                         bbox=dict(boxstyle="round", fc="black", ec="b", lw=2),
                                         arrowprops=dict(arrowstyle="->"))
annotate.set_visible(False)
days, amounts = zip(*my_dict.items())
wedges, _ = drawFigure.pie(amounts, labels=None)
drawFigure.axis('equal')
figure.canvas.mpl_connect("motion_notify_event", Hover)

def UpdateAnnotation(ind):
    data = ind.get_patch_transform() # I'm not sure this does anything useful
    # what now? can't seem to get anything working

def Hover(event):
    vis = annotate.get_visible()
    if event.inaxes == drawFigure:
        for i, w in enumerate(wedges):
            if w.contains_point([event.x, event.y]):
                print("hovering")
        figure.canvas.draw_idle()

理想情况下，我希望当我将鼠标悬停在楔形上时，会弹出一个注释，其中包含与该楔形相对应的 key : value 对。另外，把那个楔子炸开也不错。

Answer 1

您可以为每个楔形分配一个标签，该标签可以通过.get_label() 检索。可以使用textprops={'visible': False} 将标签文本设置为不可见。

要“爆炸”一个楔子，您可以移动它的中心，使用方向的平均角度。

为了使注释文本在黑色背景上可区分，可以选择浅色文本。

import numpy as np
import matplotlib.pyplot as plt

def hover_func(event):
    global selected_wedge
    if selected_wedge is not None:
        selected_wedge.set_center((0, 0))
        selected_wedge = None
    if event.inaxes == ax:
        for w in wedges:
            if w.contains_point([event.x, event.y]):
                annotation.set_text(f'{w.get_label()}: {months[w.get_label()]}')
                annotation.xy = (event.xdata, event.ydata)
                annotation.set_visible(True)
                theta = np.radians((w.theta1 + w.theta2) / 2)
                w.set_center((.2 * np.cos(theta), .2 * np.sin(theta)))
                selected_wedge = w
                fig.canvas.draw_idle()
    if selected_wedge is None and annotation.get_visible():
        annotation.set_visible(False)
        fig.canvas.draw_idle()

selected_wedge = None
fig, ax = plt.subplots()
annotation = ax.annotate("", xy=(0, 0), xytext=(-20, 20), textcoords="offset points",
                         color='yellow',
                         bbox=dict(boxstyle="round", fc="black", ec="b", lw=2),
                         arrowprops=dict(arrowstyle="->"))
annotation.set_visible(False)
months = {'January': 31, 'February': 29, 'March': 31, 'April': 30, 'May': 31, 'June': 30,
          'July': 31, 'August': 31, 'September': 30, 'October': 31, 'November': 30, 'December': 31}
wedges, _ = ax.pie(months.values(), labels=months.keys(), textprops={'visible': False},
                   colors=plt.get_cmap('plasma', len(months)).colors)
fig.canvas.mpl_connect("motion_notify_event", hover_func)

plt.show()