Custom Matplotlib Grid Axes Creation

Introduction

In this lab, we will learn how to create a custom grid of axes with Matplotlib using the mpl_toolkits.axes_grid1 module. We will create two examples: one with fixed axes sizes and paddings, and another with scalable axes sizes and fixed paddings.

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Skills Graph

Importing Required Libraries

We will start by importing the required libraries: matplotlib.pyplot for visualization and mpl_toolkits.axes_grid1 for creating the custom grid of axes.

import matplotlib.pyplot as plt
from mpl_toolkits.axes_grid1 import Divider, Size

Defining Helper Function

We will define a helper function label_axes() that will be used to place a label at the center of an axes and remove the axis ticks.

def label_axes(ax, text):
    """Place a label at the center of an Axes, and remove the axis ticks."""
    ax.text(.5, .5, text, transform=ax.transAxes,
            horizontalalignment="center", verticalalignment="center")
    ax.tick_params(bottom=False, labelbottom=False,
                   left=False, labelleft=False)

Creating a Custom Grid of Axes with Fixed Sizes and Paddings

We will create a custom grid of axes with fixed sizes and paddings. We will use the Divider class to divide the axes rectangle into a grid with sizes specified by horiz * vert. We will then add four axes to the figure using the add_axes() method and specify the positions of each axes using the new_locator() method of the Divider class.

## Sizes are in inches.
horiz = [Size.Fixed(1.), Size.Fixed(.5), Size.Fixed(1.5), Size.Fixed(.5)]
vert = [Size.Fixed(1.5), Size.Fixed(.5), Size.Fixed(1.)]

rect = (0.1, 0.1, 0.8, 0.8)
fig = plt.figure(figsize=(6, 6))
fig.suptitle("Fixed axes sizes, fixed paddings")

div = Divider(fig, rect, horiz, vert, aspect=False)

## The rect parameter will actually be ignored and overridden by axes_locator.
ax1 = fig.add_axes(rect, axes_locator=div.new_locator(nx=0, ny=0))
label_axes(ax1, "nx=0, ny=0")
ax2 = fig.add_axes(rect, axes_locator=div.new_locator(nx=0, ny=2))
label_axes(ax2, "nx=0, ny=2")
ax3 = fig.add_axes(rect, axes_locator=div.new_locator(nx=2, ny=2))
label_axes(ax3, "nx=2, ny=2")
ax4 = fig.add_axes(rect, axes_locator=div.new_locator(nx=2, nx1=4, ny=0))
label_axes(ax4, "nx=2, nx1=4, ny=0")

plt.show()

Creating a Custom Grid of Axes with Scalable Sizes and Fixed Paddings

We will create another custom grid of axes with scalable sizes and fixed paddings. We will use the Size.Scaled() option to specify axes sizes that scale with the figure size. The remaining steps are similar to the previous example.

## Sizes are in inches.
horiz = [Size.Scaled(1.5), Size.Fixed(.5), Size.Scaled(1.), Size.Scaled(.5)]
vert = [Size.Scaled(1.), Size.Fixed(.5), Size.Scaled(1.5)]

rect = (0.1, 0.1, 0.8, 0.8)
fig = plt.figure(figsize=(6, 6))
fig.suptitle("Scalable axes sizes, fixed paddings")

div = Divider(fig, rect, horiz, vert, aspect=False)

## The rect parameter will actually be ignored and overridden by axes_locator.
ax1 = fig.add_axes(rect, axes_locator=div.new_locator(nx=0, ny=0))
label_axes(ax1, "nx=0, ny=0")
ax2 = fig.add_axes(rect, axes_locator=div.new_locator(nx=0, ny=2))
label_axes(ax2, "nx=0, ny=2")
ax3 = fig.add_axes(rect, axes_locator=div.new_locator(nx=2, ny=2))
label_axes(ax3, "nx=2, ny=2")
ax4 = fig.add_axes(rect, axes_locator=div.new_locator(nx=2, nx1=4, ny=0))
label_axes(ax4, "nx=2, nx1=4, ny=0")

plt.show()

Summary

In this lab, we learned how to create a custom grid of axes with Matplotlib using the mpl_toolkits.axes_grid1 module. We created two examples: one with fixed axes sizes and paddings, and another with scalable axes sizes and fixed paddings. We used the Divider class to divide the axes rectangle into a grid with sizes specified by horiz * vert and added axes to the figure using the add_axes() method and new_locator() method of the Divider class.