Matplotlib 滑块和图形下的阴影

Question

我正在尝试创建一个带有滑块的交互式图形，但我还想在我正在绘制的图形下方添加阴影区域。以下代码（改编自 Interactive matplotlib plot with two sliders）生成一个交互式图表：

import numpy as np
from numpy import pi
import matplotlib.pyplot as plt
from matplotlib.widgets import Slider

#Define the function we're graphing
def gaussian(x, sigma):
    N = pow(2*pi,-0.5)/sigma
    Z = x/sigma
    return N*np.exp(-Z*Z/2)

#Default standard deviation of 1
std0=1

#Set up initial default data
X = np.arange(-5,5,0.1)
Y = gaussian(X,std0)

#Create an axis for main graph
fig, ax = plt.subplots(1,1)
ax.set_xlim([-5,5])
ax.set_ylim([0,1])

#[line] will be modified later with new Y values
[line]=ax.plot(X,Y)
#this moves the figure up so that it's not on top of the slider
fig.subplots_adjust(bottom=0.4)

#Create slider
sigma_slider_ax = fig.add_axes([0.25,0.25,0.65,0.03])
sigma_slider = Slider(sigma_slider_ax, 'Standard Deviation', 0.5,2.0,valinit=std0)

#Define what happens when sliders changed
def line_update(val):
    Y = gaussian(X,sigma_slider.val)
    line.set_ydata(Y)
    fig.canvas.draw_idle()
#Call the above function when the slider is changed
sigma_slider.on_changed(line_update)

plt.show()

我想要的是它在图表下的阴影。如果它不是交互式的，那么解决方案位于： How to shade region under the curve in matplotlib 效果很好（即使用 ax.fill(X,Y) 而不是 ax.plot(X,Y)）。但是，通过交互，我得到一个错误：

"AttributeError: 'Polygon' 对象没有属性 'set_ydata'"

知道如何实现吗？

Answer 1

在 pyplot 中，您可以使用 fill_between 填充曲线下方。带动画，用fill_between用白色填充清除之前的数据。

这是更新后的代码：

#Define what happens when sliders changed
def line_update(val):
    ax.fill_between([-5,5], [1,1], facecolor='white', alpha=1)  # fill white
    #ax.fill_between(X, [1 for v in Y], facecolor='white', alpha=1)  # fill white
    Y = gaussian(X,sigma_slider.val)
    line.set_ydata(Y)
    ax.fill_between(X, Y, facecolor='blue', alpha=0.30) # fill blue
    fig.canvas.draw_idle()

#Call the above function when the slider is changed
sigma_slider.on_changed(line_update)
line_update(0)  # fill curve first time

plt.show()

输出