# SelectCudaDevice

## Introduction

The **`SelectCudaDevice`** widget in Supervisely is a user interface element that enables users to select CUDA devices available on their agent. It automatically detects and lists the devices, displaying each with its corresponding RAM usage. Additionally, a refresh button allows users to update the list and view real-time device and memory usage. The widget also includes an event handler that activates when a user selects a device from the dropdown menu.

## Function signature

```python
SelectCudaDevice(
    get_list_on_init = True,
    sort_by_free_ram = False,
    include_cpu_option = False,
    widget_id = None,
)
```

![default](https://github.com/user-attachments/assets/4a971741-3cc8-4844-b116-6abd40c751e2)

## Parameters

| Parameters           |       Type       |                                            Description                                           |
| -------------------- | :--------------: | :----------------------------------------------------------------------------------------------: |
| `get_list_on_init`   | `Optional[bool]` | Whether to retrieve and display the list of CUDA devices upon initialization. Default is `True`. |
| `sort_by_free_ram`   | `Optional[bool]` |         Whether to sort the CUDA devices by their available free RAM. Default is `False`.        |
| `include_cpu_option` | `Optional[bool]` |            Whether to include CPU as an option in the device list. Default is `False`.           |
| `widget_id`          |       `str`      |                                  An optional ID for the widget.                                  |

### get\_list\_on\_init

Determine if you want to get the device list on widget initialization. If `True`, the widget retrieves information about device on initialization. Default is `True`.

**type:** `Optional[bool]`

**default value:** `True`

Initialize the empty widget, and then manually refresh it to find the devices:

```python
widget = SelectCudaDevice(get_list_on_init=False)

# some code here

widget.refresh()
```

### sort\_by\_free\_ram

If `True`, the device list will automatically be sorted by its free RAM value. Default is `False`.

**type:** `Optional[bool]`

**default value:** `False`

Initialize the widget sorting it by free RAM:

```python
widget = SelectCudaDevice(sort_by_free_ram=True)
```

![sort\_by\_free\_ram](https://github.com/user-attachments/assets/13f47e61-e924-4386-903a-62ae0ecb96fc)

### include\_cpu\_option

If `True`, selector will include CPU as a device option. Default is `False`.

**type:** `Optional[bool]`

**default value:** `False`

Initialize the widget with CPU as a device option:

```python
widget = SelectCudaDevice(include_cpu_option=True)
```

### widget\_id

An optional ID for the widget.

**type:** `str`

**default value:** `None`

Initialize the widget with an ID:

```python
widget = SelectCudaDevice(widget_id="select_cuda_device")
```

## Methods and attributes

|  Methods and Attributes  |                                         Description                                         |
| :----------------------: | :-----------------------------------------------------------------------------------------: |
|      `get_device()`      |                                Get currently selected device.                               |
| `set_device(value: str)` |              Set the device to be displayed in the widget (overrides current).              |
|        `refresh()`       | Get up-to-date information about available devices and set them as options in the selector. |

## Mini app example

You can find this example in our GitHub repository:

[selection/023\_select\_cuda\_device/src/main.py](https://github.com/supervisely-ecosystem/ui-widgets-demos/blob/master/selection/023_select_cuda_device/src/main.py)

### Import libraries

```python
import os

import supervisely as sly
from dotenv import load_dotenv
from supervisely.app.widgets import Card, SelectCudaDevice, Container, Text
```

### Init API client

First, we load environment variables with credentials and init API for communicating with Supervisely Instance:

```python
load_dotenv("local.env")
load_dotenv(os.path.expanduser("~/supervisely.env"))
api = sly.Api()
```

### Initialize the `SelectCudaDevice` widget

Let's initialize the `SelectCudaDevice` widget with no devices:

```python
cuda_device = SelectCudaDevice(
    get_list_on_init=False,
    include_cpu_option=True,
)
```

Then, we can manually refresh the widget, retrieving the devices information when we need to.

```python
cuda_device.refresh()
```

### Create an event handler for the `SelectCudaDevice` widget

Now, let's create a event handler for the SelectCudaDevice widget, when the value of the widget is changed.

```python
value_changed_info = Text(status="info")
value_changed_info.hide()


@cuda_device.value_changed
def new_device_selected(device: str):
    text = "Value changed: {}".format(device)
    value_changed_info.text = text
    value_changed_info.show()
```

### Create app layout

Prepare a layout for the app using `Card` widget with the `content` parameter and place widget that we've just created in the `Container` widget.

```python
card = Card(
    title="Select Cuda Device",
    content=Container(widgets=[value_changed_info, cuda_device]),
)

layout = Container(widgets=[card])
```

### Create an app using the layout

Create an app object with the layout parameter.

```python
app = sly.Application(layout=layout)
```

![mini\_app](https://github.com/user-attachments/assets/13f47e61-e924-4386-903a-62ae0ecb96fc)