Small function to add a coordinate system indicator without visible axes to a umap-plot

add umap xy-indicator as ax.py

def add_inset_axes(base_ax, inset_position, inset_size, line_length_ratio=0.4):
    """
    Adds an inset axis with a UMAPX/Y indicator into a Matplotlib figure.

    Parameters:
    - base_ax: The base axes to which the inset will be added.
    - inset_position: The position of the inset in figure space (x, y).
    - inset_size: Width and height of the inset in figure space (width, height).
    - line_length_ratio: The ratio of the line length to the inset size.

    Returns:
    - ax_inset: The inset axes.
    """
    # Create the inset axis with a fixed aspect ratio:
    ax_inset = fig.add_axes([inset_position[0], inset_position[1], inset_size[0], inset_size[1]], aspect='equal')
    ax_inset.patch.set_alpha(0)  # Make inset background transparent
    ax_inset.axis('off')  # Turn off the inset axes
    
    # Calculate the line lengths based on the inset size and ratio:
    line_length = line_length_ratio * min(inset_size)
    
    # Draw the x-lines & text:
    ax_inset.plot([0, line_length], [0, 0], color='k', lw=4,solid_capstyle='projecting')
    ax_inset.text(0, -0.003, 'UMAP-X', ha='left', va='top', fontsize=10,fontweight='bold')

    # Draw the y-lines & text:
    ax_inset.vlines(x=0, ymin=0, ymax=line_length, color='k', lw=4)
    ax_inset.text(-0.002, 0, 'UMAP-Y', ha='right', va='bottom', fontsize=10, rotation=90,fontweight='bold')
    
    return ax_inset

add_inset_axes(ax, (0.2,0.35), (0.05,0.05))