Add bracket function for matplotlib

add_bracket.py

# Bracket annotation function

def add_bracket(ax, x0, x1, y, text='', xycoords='data', bracket_height=12, pointer_height=6, arrowprops=None, color='blue', linewidth=1, rad=10, **kwargs):
    """
    Adds a bracket annotation to the given axes.
    Returns the last annotation patch.

    Parameters:
        ax (matplotlib.axes._axes.Axes): The axes to annotate.
        x0 (float): The starting x-coordinate of the bracket.
        x1 (float): The ending x-coordinate of the bracket.
        y (float): The y-coordinate of the bracket.
        text (str, optional): Annotation text. Default is an empty string.
        xycoords (str, optional): coordinate system for positioning.
        bracket_height (float, optional): The height of the bracket offset. Default is 12.
        pointer_height (float, optional): Height of the text pointer. Default is 6.
        arrowprops (dict, optional): Properties for the arrow. Default is None.
        color (str, optional): Color of the bracket and pointer. Default is 'blue'.
        linewidth (float, optional): Line width of the bracket and pointer. Default is 1.
        rad (float, optional): Radius of the bracket corners. Default is 10.
        kwargs: additional arguments passed to annotate (font size etc.).

    Returns:
        matplotlib.text.Annotation: The last annotation patch added to the axes.
    """
    if arrowprops is None:
        arrowprops = dict(
            color=color,
            arrowstyle="-",
            connectionstyle=f"angle,angleA=0,angleB=90,rad={rad}",
            relpos=(1, 0.5),
            shrinkA=0,
            shrinkB=0,
            linewidth=linewidth
        )
    # bracket arms
    ann1 = ax.annotate('', xy=(x0, y), xycoords=xycoords, textcoords=('data', 'offset points'), xytext=((x1 + x0) / 2, bracket_height), arrowprops=arrowprops)
    ann2 = ax.annotate('', xy=(x1, y), xycoords=xycoords, textcoords=('data', 'offset points'), xytext=((x1 + x0) / 2, bracket_height), arrowprops=arrowprops)
    
    # mid pointer and text (optional), position relative to ann1
    ann_end = ax.annotate(text, xy=(1,1), xycoords=ann1, textcoords='offset points', xytext=(0, pointer_height), 
        bbox=dict(boxstyle="square,pad=0.1", 
            fc='#fff0', ec='white', 
            lw=0 ),
        arrowprops=dict(
            arrowstyle="-",
            shrinkA=0,
            shrinkB=0,
            relpos=(0, 0.5),
            color=color,
            linewidth=linewidth),
            **kwargs
                    )
    return ann_end

# Example usage:
add_bracket(ax, x0=1.56, x1=7.84, y=1, text='Hello brackets', bracket_height=22, pointer_height=12, fontsize=12)
add_bracket(ax, x0=4.71, x1=7.84, y=1, text='Im smol', bracket_height=12, pointer_height=12, color='red', rad=15)

Draws brackets like this by leveraging matplotlib's built-in annotate function.
https://matplotlib.org/stable/users/explain/text/annotations.html#annotations