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Matplotlib is a plotting library for Python that allows users to create visualizations with ease. In order to make text bold in Matplotlib, you must use the fontweight parameter and set it to ‘bold’. The fontweight parameter is available within the text() function, which allows you to add text to a plot. Examples of how to use this parameter are provided within this article.
You can use the weight argument to create a bold font in Matplotlib.
This argument is commonly used with titles and annotated text in Matplotlib:
Method 1: Use Bold Font in Title
plt.title('My Title', weight='bold')
Method 2: Use Bold Font in Annotated Text
plt.text(6, 10, 'some text', weight='bold')
The following examples show how to use each method in practice.
Example 1: Use Bold Font in Title
The following code shows how to create a scatterplot with a title in Matplotlib that uses regular font:
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 title plt.title('My Title', fontsize=22)
And the following code shows how to create a scatterplot with a title in Matplotlib and use the weight argument to enable bold font:
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 title plt.title('My Title', fontsize=22, weight='bold')
Example 2: Use Bold Font in Annotated Text
The following code shows how to use the weight argument to enable bold font in an annotated text in a Matplotlib scatterplot:
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 regular text plt.text(6, 10, 'Normal Font', fontsize=16) #add bold text plt.text(10, 10, 'Bold Font', fontsize=16, weight='bold')
Notice the difference between the normal font and the bold font.
The following tutorials explain how to perform other common tasks in Matplotlib: