Change matplotlib line style in mid-graph

Last Updated : 12 Nov, 2020

Prerequisite: Matplotlib

In this article we will learn how to change line style in mid-graph using matplotlib in Python.

Matplotlib: It is a tremendous visualization library in Python for 2D plots of arrays. Matplotlib may be a multi-platform data visualization library built on NumPy arrays and designed to figure with the broader SciPy stack. It was introduced by John Hunter within the year 2002.
Line style: Line style is a feature that describes in which fashion or style line is drawn. Following image shows the key that has to provided as input parameter and what line style it will produce:

Approach:

Import the matplotlib.pyplot library and other for data (optional)
Import or create some data
Draw a graph plot with different line style is middle.

Example 1:

In this example we will use simple steps mentioned above and form a graph with two different line styles.

Python3

# importing packages 
import matplotlib.pyplot as plt 
import numpy as np 
  
# create data 
x = np.linspace(0, 10, 100) 
y = 3 * x + 2
  
below = y < 15
above = y >= 15
  
# Plot lines below as dotted------- 
plt.plot(x[below], y[below], '--') 
  
# Plot lines above as solid________ 
plt.plot(x[above], y[above], '-') 
  
plt.show() 

Output :

Example 2 :

In this example we will use simple steps mentioned above and form a graph with two different line styles in one sine function.

Python3

# importing packages 
import matplotlib.pyplot as plt 
import numpy as np 
  
# create data 
x = np.linspace(0, 10, 100) 
y = np.sin(x) 
  
below = y < .5
above = y >= .5
  
# Plot lines below as dotted------- 
plt.plot(x[below], y[below], '--') 
  
# Plot lines above as solid_______ 
plt.plot(x[above], y[above], '-') 
  
plt.show() 

Output :

Example 3 :

This is similar to above example with extra cosine function to show different feature of line styles in mid graph.

Python3

# importing packages 
import matplotlib.pyplot as plt 
import numpy as np 
  
# create data 
x = np.linspace(0, 10, 100) 
y1 = np.sin(x) 
y2 = np.cos(x) 
  
below = abs(y1-y2) < .2
above = abs(y1-y2) >= .2
  
# Plot lines below as dotted------- 
plt.plot(x[below], y1[below], 'r--') 
  
# Plot lines below as dotted------- 
plt.plot(x[below], y2[below], 'g--') 
  
# Plot lines above as solid_______ 
plt.plot(x[above], y1[above], 'r-') 
  
# Plot lines above as solid_______ 
plt.plot(x[above], y2[above], 'g-') 
  
plt.show() 