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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
)

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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.

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Attributes

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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.

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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

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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

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