Table of Contents
Matplotlib is a powerful library used for creating visualizations in Python. One of its many features includes the ability to draw arrows on plots. To draw arrows in Matplotlib, the user can utilize the “arrow()” function which takes in parameters such as the starting and ending coordinates of the arrow, its width, length, and color. Additionally, Matplotlib provides the option to customize the appearance of the arrow, such as changing the arrowhead style or adding a text label. This functionality allows for precise and clear annotations on plots, making it a valuable tool for data analysis and presentation.
Draw Arrows in Matplotlib
To draw arrows in Matplotlib, you can use thematplotlib.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.pyplotas 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()
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.pyplotas 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()
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.pyplotas 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()
Example 3: Add Annotations to Arrows
The following code shows how to add an annotation underneath an arrow on a Matplotlib plot:
import matplotlib.pyplotas 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()
Additional Resources
How to Plot Circles in Matplotlib (With Examples)
How to Draw Rectangles in Matplotlib (With Examples)