Plot is unclear using matplotlib and pandas library

Question

Any explication why I got this kind of plot? The range of index returns is from 100 to 130. I need help to understand this plot above. The code is simple, but the plot

Answer 1

Matplotlib plots the data in the order it is provided. You may sort the data if that is required.

import numpy as np
import matplotlib.pyplot as plt

x = np.array([3, 5, 1, 2, 7, 4, 6, 9, 8])
y = np.array([8, 10, 3, 6, 8, 10, 10, 3, 6])

plt.subplot(121)
plt.plot(x,y, marker="o", label="unsorted")

plt.legend()

# now sort the values
plt.subplot(122)
plt.plot(np.sort(x),y[np.argsort(x)], marker="o", color="C3", label="sorted")

plt.legend()
plt.show()