> ## Documentation Index
> Fetch the complete documentation index at: https://mintlify.com/marimo-team/marimo/llms.txt
> Use this file to discover all available pages before exploring further.

# matplotlib

Make reactive selections on matplotlib plots.

## Usage

```python theme={null}
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
```

```python theme={null}
# Filter data using the selection
mask = ax.value.get_mask(x, y)
selected_x, selected_y = x[mask], y[mask]
```

```python theme={null}
# Check if anything is selected
if ax.value:
    print("Data has been selected")
```

## Signature

```python theme={null}
mo.ui.matplotlib(
    axes: Axes,
    *,
    debounce: bool = False
)
```

## Parameters

<ParamField path="axes" type="Axes" required>
  A matplotlib `Axes` object. The full figure is rendered, but selections map to this axes' coordinate space.
</ParamField>

<ParamField path="debounce" type="bool" default="False">
  If `True`, the selection is only sent to Python on mouse-up. If `False` (the default), it streams while dragging.
</ParamField>

## Attributes

<ParamField path="value" type="MatplotlibSelection">
  The selected data, with `get_mask(x, y)` returning a mask array corresponding to the selection.
</ParamField>

<ParamField path="axes" type="Axes">
  The associated matplotlib Axes object.
</ParamField>

## 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