How to Adjust Marker Size in Matplotlib (With Examples)


You can use the s argument to adjust the marker size of points in Matplotlib:

plt.scatter(x, y, s=40) 

The following examples show how to use this syntax in practice.

Example 1: Set a Single Marker Size for All Points

The following code shows how to create a scatterplot in Matplotlib and set a single marker size for all points in the 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)

Marker size in Matplotlib

The larger the number we specify for the argument, the larger the points will be in the 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 120
plt.scatter(A, B, s=120)

Markersize adjustment in scatterplot of Matplotlib

Example 2: Set Different Marker Sizes for Each Point

The following code shows how to create a scatterplot in Matplotlib and set a different marker size for each point in the 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]

#define array of marker sizes to use
sizes = [20, 40, 60, 80, 100, 150]

#create scatterplot, using marker sizes specified in array
plt.scatter(A, B, s=sizes)

Different marker sizes in Matplotlib scatterplot

Example 3: Use a Function to Define Marker Sizes

The following code shows how to create a scatterplot in Matplotlib and use a function to define the marker sizes to use for each point in the 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]

#define array of marker sizes to use
sizes = [3**n for n in range(len(A))]

#create scatterplot, using marker sizes specified in function
plt.scatter(A, B, s=sizes)

Marker size function in Matplotlib in Python

You can find the complete Matplotlib documentation for adjusting marker size here.

Additional Resources

The following tutorials explain how to perform other common operations in Matplotlib:

How to Annotate Matplotlib Scatterplots
How to Add Legend to Scatterplot in Matplotlib

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