The **aspect ratio** of a matplotlib plot refers to the aspect of the axis scaling, i.e. the ratio of y-unit to x-unit.

This ratio can be modified by using the matplotlib.axes.Axes.set_aspect() function.

Under the hood, the **set_aspect()** function actually modifies something known as the **data coordinate system** but in practice we typically want to modify the **display coordinate system**.

To make this conversion easy, we can use this bit of code:

#define y-unit to x-unit ratio ratio = 1.0 #get x and y limits x_left, x_right = ax.get_xlim() y_low, y_high = ax.get_ylim() #set aspect ratio ax.set_aspect(abs((x_right-x_left)/(y_low-y_high))*ratio)

Let’s walk through an example of using this function in practice.

**Step 1: Create a Basic Matplotlib Plot**

First, let’s create a simple line chart using Matplotlib:

import matplotlib.pyplot as plt #define matplotlib figure and axis fig, ax = plt.subplots() #create simple line plot ax.plot([0, 10],[0, 20]) #display plot plt.show()

**Step 2: Set the Aspect Ratio (The Wrong Way)**

Notice that the x-axis is longer than the y-axis. Let’s attempt to set the aspect ratio to 1, i.e. the x-axis and y-axis should be equal:

import matplotlib.pyplot as plt #define matplotlib figure and axis fig, ax = plt.subplots() #create simple line plot ax.plot([0, 10],[0, 20]) #attempt to set aspect ratio to 1 ax.set_aspect(1) #display plot plt.show()

Notice that this did not work as we expected. The y-axis is much longer than the x-axis.

**Step 3: Set the Aspect Ratio (The Right Way)**

The following code shows how to use a simple calculation to set the correct aspect ratio:

import matplotlib.pyplot as plt #define matplotlib figure and axis fig, ax = plt.subplots() #create simple line plot ax.plot([0, 10],[0, 20]) #set aspect ratio to 1 ratio = 1.0 x_left, x_right = ax.get_xlim() y_low, y_high = ax.get_ylim() ax.set_aspect(abs((x_right-x_left)/(y_low-y_high))*ratio) #display plot plt.show()

Notice that this plot has the aspect ratio we expected. The x-axis and y-axis are equal lengths.

**Step 4: Adjust the Aspect Ratio to Whatever You’d Like**

If we’d like the y-axis to be longer than the x-axis, we can simply specify the aspect ratio to be some number greater than 1:

import matplotlib.pyplot as plt #define matplotlib figure and axis fig, ax = plt.subplots() #create simple line plot ax.plot([0, 10],[0, 20]) #set aspect ratio to 3 ratio = 3 x_left, x_right = ax.get_xlim() y_low, y_high = ax.get_ylim() ax.set_aspect(abs((x_right-x_left)/(y_low-y_high))*ratio) #display plot plt.show()

And if we’d like the y-axis to be shorter than the x-axis, we can simply specify the aspect ratio to be some number less than 1:

import matplotlib.pyplot as plt #define matplotlib figure and axis fig, ax = plt.subplots() #create simple line plot ax.plot([0, 10],[0, 20]) #set aspect ratio to .3 ratio = .3 x_left, x_right = ax.get_xlim() y_low, y_high = ax.get_ylim() ax.set_aspect(abs((x_right-x_left)/(y_low-y_high))*ratio) #display plot plt.show()

*You can find more Matplotlib tutorials here.*