How to Draw Arrows in Matplotlib

To draw arrows in Matplotlib, you can use the matplotlib.pyplot.arrow function, which uses the following syntax:

matplotlib.pyplot.arrow(x, y, dx, dy)

where:

x, y: The x and y coordinates of the arrow base
dx, dy: The length of the arrow along the x and y direction

This tutorial provides several examples of how to use this function in practice.

Example 1: Draw a Single Arrow

The following code shows how to draw a single arrow on a Matplotlib plot:

import matplotlib.pyplot as plt

#define two arrays for plotting
A = [3, 5, 5, 6, 7, 8]
B = [12, 14, 17, 20, 22, 27]

#create scatterplot, specifying marker size to be 40
plt.scatter(A, B, s=40)

#add arrow to plot
plt.arrow(x=4, y=18, dx=2, dy=5, width=.08) 
  
#display plot 
plt.show()

Arrow in matplotlib plot

Note that we can set dx=0 to create a vertical arrow and dy=0 to create a horizontal arrow.

For example, here’s how to create a vertical arrrow:

import matplotlib.pyplot as plt

#define two arrays for plotting
A = [3, 5, 5, 6, 7, 8]
B = [12, 14, 17, 20, 22, 27]

#create scatterplot, specifying marker size to be 40
plt.scatter(A, B, s=40)

#add arrow to plot
plt.arrow(x=4, y=18, dx=0, dy=5, width=.08) 
  
#display plot 
plt.show()

Vertical arrow in matplotlib

Example 2: Style an Arrow

By default, an arrow in Matplotlib is blue with black edges but we can easily change this by using the facecolor and edgecolor arguments:

import matplotlib.pyplot as plt

#define two arrays for plotting
A = [3, 5, 5, 6, 7, 8]
B = [12, 14, 17, 20, 22, 27]

#create scatterplot, specifying marker size to be 40
plt.scatter(A, B, s=40)

#add arrow to plot
plt.arrow(x=4, y=18, dx=0, dy=5, width=.08, facecolor='red', edgecolor='none') 
  
#display plot 
plt.show()

Arrow with custom color in matplotlib

You can find a complete list of styling properties that can be applied to arrows here.

Example 3: Add Annotations to Arrows

The following code shows how to add an annotation underneath an arrow on a Matplotlib plot:

import matplotlib.pyplot as plt

#define two arrays for plotting
A = [3, 5, 5, 6, 7, 8]
B = [12, 14, 17, 20, 22, 27]

#create scatterplot, specifying marker size to be 40
plt.scatter(A, B, s=40)

#add arrow to plot
plt.arrow(x=4, y=18, dx=0, dy=5, width=.08) 

#add annotation
plt.annotate('General direction', xy = (3.4, 17))
  
#display plot 
plt.show()