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Annotating Matplotlib Scatterplots is the process of adding text to the data points within a scatterplot. This text can be used to provide information about the data points such as their labels, values, or other related data. Annotating a Matplotlib Scatterplot can help make the data more legible and understandable to viewers.
You can use the following basic syntax to annotate scatter plots in Matplotlib:
#add 'my text' at (x, y) coordinates = (6, 9.5) plt.text(6, 9.5, 'my text')
The following examples show how to use this syntax in practice.
Create Basic Scatterplot
The following code shows how to create a basic scatterplot using Matplotlib:
import matplotlib.pyplot as plt #create data x = [3, 6, 8, 12, 14] y = [4, 9, 14, 12, 9] #create scatterplot plt.scatter(x, y)
Annotate a Single Point
We can use the following code to add an annotation to a single point in the plot:
import matplotlib.pyplot as plt #create data x = [3, 6, 8, 12, 14] y = [4, 9, 14, 12, 9] #create scatterplot plt.scatter(x, y) #add text 'Here' at (x, y) coordinates = (6, 9.5) plt.text(6, 9.5, 'Here')
Annotate Multiple Points
We can use the following code to add annotations to multiple points in the plot:
import matplotlib.pyplot as plt #create data x = [3, 6, 8, 12, 14] y = [4, 9, 14, 12, 9] #create scatterplot plt.scatter(x, y) #add text to certain points plt.text(3, 4.5, 'This') plt.text(6, 9.5, 'That') plt.text(8.2, 14, 'Those')
Annotate All Points
We can use the following code to add annotations to every single point in the plot:
import matplotlib.pyplot as plt #create data x = [3, 6, 8, 12, 14] y = [4, 9, 14, 12, 9] labs = ['A', 'B', 'C', 'D', 'E'] #create scatterplot plt.scatter(x, y) #use for loop to add annotations to each point in plot for i, txt in enumerate(labs): plt.annotate(txt, (x[i], y[i]))
By default, the annotations are placed directly on top of the points in the scatterplot and the default font size is 10.
The following code shows how to adjust both of these settings so the annotations are slightly to the right of the points and the font size is slightly larger:
import matplotlib.pyplot as plt #create data x = [3, 6, 8, 12, 14] y = [4, 9, 14, 12, 9] labs = ['A', 'B', 'C', 'D', 'E'] #create scatterplot plt.scatter(x, y) #use for loop to add annotations to each point in plot for i, txt in enumerate(labs): plt.annotate(txt, (x[i]+.25, y[i]), fontsize=12)
The following tutorials explain how to perform other common tasks in Matplotlib: