matplotlib

Make reactive selections on matplotlib plots.

Usage

import matplotlib.pyplot as plt
import marimo as mo
import numpy as np

x = np.arange(5)
y = x**2
plt.scatter(x=x, y=y)
ax = mo.ui.matplotlib(plt.gca())
ax

# Filter data using the selection
mask = ax.value.get_mask(x, y)
selected_x, selected_y = x[mask], y[mask]

# Check if anything is selected
if ax.value:
    print("Data has been selected")

Signature

mo.ui.matplotlib(
    axes: Axes,
    *,
    debounce: bool = False
)

Parameters

axes · Axes · required

A matplotlib Axes object. The full figure is rendered, but selections map to this axes’ coordinate space.

debounce · bool · default: "False"

If True, the selection is only sent to Python on mouse-up. If False (the default), it streams while dragging.

Attributes

value · MatplotlibSelection

The selected data, with get_mask(x, y) returning a mask array corresponding to the selection.

axes · Axes

The associated matplotlib Axes object.

Selection Types

The figure is rendered as a static image with an interactive selection overlay:

• Click and drag for box selection
• Hold the Shift key and drag for lasso selection

BoxSelection

A rectangular box selection on a matplotlib plot.

Attributes:

• x_min: Left boundary of the selection
• x_max: Right boundary of the selection
• y_min: Bottom boundary of the selection
• y_max: Top boundary of the selection

Methods:

• get_mask(x, y): Get a boolean mask for points within this selection

LassoSelection

A freehand polygon (lasso) selection on a matplotlib plot.

Attributes:

• vertices: The polygon vertices as a tuple of (x, y) pairs

Methods:

• get_mask(x, y): Get a boolean mask for points within this selection

EmptySelection

Sentinel representing no selection. Returned by mo.ui.matplotlib.value when nothing is selected.

Behaves like a selection with no points, and evaluates to False when coerced as a bool.

Methods:

• get_mask(x, y): Return an all-False mask