曲线之间的着色交点

Question

I want to colour the intersection between a cumulative probability function (CDF) and the step function. Here is my code

import matplotlib.pyplot as plt
import numpy as np
import pandas as pd
import seaborn as sns
from scipy.stats import norm


np.random.seed(1024)

mu = 200
sigma = 25
n_bins = 50
bins = np.array([121.95403681, 124.56265713, 127.17127746, 129.77989779,
                 132.38851812, 134.99713844, 137.60575877, 140.2143791 ,
                 142.82299943, 145.43161975, 148.04024008, 150.64886041,
                 153.25748074, 155.86610106, 158.47472139, 161.08334172,
                 163.69196205, 166.30058237, 168.9092027 , 171.51782303,
                 174.12644336, 176.73506368, 179.34368401, 181.95230434,
                 184.56092467, 187.16954499, 189.77816532, 192.38678565,
                 194.99540598, 197.6040263 , 200.21264663, 202.82126696,
                 205.42988729, 208.03850761, 210.64712794, 213.25574827,
                 215.8643686 , 218.47298892, 221.08160925, 223.69022958,
                 226.29884991, 228.90747023, 231.51609056, 234.12471089,
                 236.73333122, 239.34195154, 241.95057187, 244.5591922 ,
                 247.16781253, 249.77643285, 252.38505318])

my_norm = norm(loc=mu, scale=sigma)
x = np.random.normal(mu, sigma, size=100)

fig, ax = plt.subplots(figsize=(8, 4))

# Add a line showing the expected distribution.
y = ((1 / (np.sqrt(2 * np.pi) * sigma)) * np.exp(-0.5 * (1 / sigma * (bins - mu))**2))
y = y.cumsum()
y /= y[-1]

step_x = [10, 20, 30, 40, 50]
step_y = [0.02, 0.1, 0.3, 0.7, 1]

ax.plot(step_x, step_y, drawstyle='steps-pre')
cdf_x = range(n_bins+1)
ax.plot(cdf_x, y, color='black', linewidth=2)
# tidy up the figure
ax.grid(False)
# ax.legend(loc='right')
ax.set_title('CDF plot')
ax.set_xlabel('returns')
ax.set_ylabel('probability density')

However, by adding

ax.fill_between(cdf_x, step_y, where=None, facecolor='pink', interpolate=True)

after

ax.plot(cdf_x, y, color='black', linewidth=2)

It returns

ValueError: operands could not be broadcast together with shapes (51,) (5,) 

How can I fix it since the shape are different?

Answer 1

When use fill_between you need to provide two y-data with same length. Here I suggest you fill it step by step:

for i,iy in enumerate(step_y[1:]):
    ax.fill_between(cdf_x[10*i+10:10*i+21],y[10*i+10:10*i+21],iy,facecolor='pink')