Text Alignment in Matplotlib

Introduction

Matplotlib is a plotting library for the Python programming language and its numerical mathematics extension NumPy. This tutorial will focus on text alignment in Matplotlib.

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Skills Graph

Creating a Rectangle

We will begin by creating a rectangle in the plot using Rectangle() function of matplotlib.patches module. After creating the rectangle, we will set its horizontal and vertical limits using set_xlim() and set_ylim() functions. Finally, we will add the rectangle to the plot.

import matplotlib.pyplot as plt
from matplotlib.patches import Rectangle

fig, ax = plt.subplots()

## Build a rectangle in axes coords
left, width = .25, .5
bottom, height = .25, .5
right = left + width
top = bottom + height
p = Rectangle((left, bottom), width, height, fill=False)
ax.add_patch(p)

## Set the horizontal and vertical limits
ax.set_xlim(0, 1)
ax.set_ylim(0, 1)
plt.show()

Adding Text to the Rectangle

In this step, we will add text to the rectangle using the text() function. The horizontal and vertical alignment of the text will be set using the horizontalalignment and verticalalignment parameters respectively.

## Add text to the rectangle
ax.text(left, bottom, 'left top',
        horizontalalignment='left',
        verticalalignment='top',
        transform=ax.transAxes)

ax.text(left, bottom, 'left bottom',
        horizontalalignment='left',
        verticalalignment='bottom',
        transform=ax.transAxes)

ax.text(right, top, 'right bottom',
        horizontalalignment='right',
        verticalalignment='bottom',
        transform=ax.transAxes)

ax.text(right, top, 'right top',
        horizontalalignment='right',
        verticalalignment='top',
        transform=ax.transAxes)

ax.text(right, bottom, 'center top',
        horizontalalignment='center',
        verticalalignment='top',
        transform=ax.transAxes)

ax.text(left, 0.5 * (bottom + top), 'right center',
        horizontalalignment='right',
        verticalalignment='center',
        rotation='vertical',
        transform=ax.transAxes)

ax.text(left, 0.5 * (bottom + top), 'left center',
        horizontalalignment='left',
        verticalalignment='center',
        rotation='vertical',
        transform=ax.transAxes)

ax.text(0.5 * (left + right), 0.5 * (bottom + top), 'middle',
        horizontalalignment='center',
        verticalalignment='center',
        transform=ax.transAxes)

ax.text(right, 0.5 * (bottom + top), 'centered',
        horizontalalignment='center',
        verticalalignment='center',
        rotation='vertical',
        transform=ax.transAxes)

ax.text(left, top, 'rotated\nwith newlines',
        horizontalalignment='center',
        verticalalignment='center',
        rotation=45,
        transform=ax.transAxes)

plt.show()

Customizing the Plot

In this step, we will customize the plot by adding axis labels and removing the axis lines.

## Customize the plot
ax.set_axis_off()
ax.set_xlabel('X Label')
ax.set_ylabel('Y Label')
ax.set_title('Text Alignment in Matplotlib')
plt.show()

Summary

In this tutorial, we learned how to align text in Matplotlib. We used the text() function to add text to a rectangle and set the horizontal and vertical alignment using the horizontalalignment and verticalalignment parameters respectively. We also customized the plot by adding axis labels and removing the axis lines.