# 5 Best Ways to Insert a Newline in Matplotlib Labels with TeX in Python

Rate this post

π‘ Problem Formulation: When using Matplotlib with TeX for typesetting mathematical expressions within plot labels, adding a newline can pose a challenge. Users often require multi-line labels to improve readability or to convey complex information. This article demonstrates how to achieve this, transforming an input such as `ax.set_title("This is an \$ax^2 + bx + c\$ equation")` into a desired output where the equation is on a new line below the text “This is an”.

## Method 1: Explicit Newline with `\\\\` in TeX Strings

The method involves adding the TeX newline character `\\\\` directly into the label string. This is particularly useful when you are writing raw TeX code in your labels. The double backslash is necessary because in LaTeX, a single backslash is used for commands.

Here’s an example:

```import matplotlib.pyplot as plt

plt.figure()
plt.title(r"This is an\\\$ax^2 + bx + c\$ equation")
plt.show()```

Output: A plot with the title “This is an” on the first line and the equation “ax^2 + bx + c” on the second line.

This code snippet uses a raw string (indicated by the `r` prefix) to prevent Python from interpreting the backslashes as escape characters. The `\\\\` is interpreted by TeX as a newline, thus splitting the title into two lines.

## Method 2: Using `textwrap` to Automate Line Breaks

If you have a long label and want to wrap the text to a new line automatically, the Python `textwrap` module can be used. This is especially handy when working with dynamically generated text where manual insertion of line breaks is unfeasible.

Here’s an example:

```import matplotlib.pyplot as plt
import textwrap

label = "This is an \$ax^2 + bx + c\$ equation"
wrapped_label = textwrap.fill(label, width=20)

plt.figure()
plt.title(wrapped_label)
plt.show()```

Output: A plot with a title automatically wrapped every 20 characters, putting part of the equation on the second line.

The `textwrap.fill` function automatically adds newlines to fit the label within a specified width of character columns. When rendered by Matplotlib, the title is accordingly split into multiple lines.

## Method 3: Using Matplotlib’s `set_title` with Keyword Arguments

Matplotlib’s `set_title` method accepts keyword arguments that can be utilized to manipulate text properties. This includes the ability to set the space between lines in a label (line spacing), effectively creating a multi-line label.

Here’s an example:

```import matplotlib.pyplot as plt

plt.figure()
plt.title("This is an\n\$ax^2 + bx + c\$ equation", linespacing=2)
plt.show()```

Output: A plot with a title where “This is an” and “ax^2 + bx + c” appear on separate lines with increased spacing.

This method uses the simple newline character (`\n`) in the string to start a new line of text. The `linespacing` argument then adjusts the space between the generated lines.

## Method 4: Using `plt.text()` for Advanced Positioning

The `plt.text()` allows for advanced text positioning, using coordinates for placing individual text elements. This gives you fine control over the layout of your text labels on the plot.

Here’s an example:

```import matplotlib.pyplot as plt

plt.figure()
plt.text(0.5, 0.9, "This is an", ha='center', va='center', transform=plt.gca().transAxes)
plt.text(0.5, 0.8, "\$ax^2 + bx + c\$", ha='center', va='center', transform=plt.gca().transAxes)
plt.show()```

Output: A plot with “This is an” precisely positioned above the equation “ax^2 + bx + c”.

This code places two separate text elements at specified axes-relative coordinates. The `ha` and `va` arguments stand for horizontal and vertical alignment, respectively, ensuring that the text is centered.

## Bonus One-Liner Method 5: Using Python’s Triple Quotes

Python’s triple quotes can be used to write multi-line strings directly. This can be a quick and handy way to format multiline text in Matplotlib without additional processing.

Here’s an example:

```import matplotlib.pyplot as plt

plt.figure()
plt.title("""This is an
\$ax^2 + bx + c\$ equation""")
plt.show()```

Output: A plot with the title spread over two lines, “This is an” followed by the equation “ax^2 + bx + c”.

By using triple quotes, any newlines entered within the string are directly interpreted as actual newlines in the output, making it a convenient one-liner method for quick plotting tasks.

## Summary/Discussion

• Method 1: Explicit Newline with `\\\\`. Direct and clear for TeX users. Requires knowledge of TeX syntax.
• Method 2: Using `textwrap`. Automated and ideal for dynamic text. Could lead to awkward breaks in mathematical expressions.
• Method 3: Matplotlib’s `set_title` Method. Simple and quick. Limited formatting control compared to other methods.
• Method 4: Using `plt.text()`. Most flexible for layout. Requires manual positioning which can be complex for dynamic or complex layouts.
• Bonus Method 5: Python’s Triple Quotes. Easiest for quick tasks. Not suitable for complex formatting or large amounts of text.