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How to use selectors

This guide highlights different selectors that can be used in a dashboard. Selectors do not serve a purpose on their own, but they enable you to change how the input is given to other models, for example, the Filter or the Parameter model.

The Filter or the Parameter model accept the selector argument, where a selector model can be entered to choose how the user should input their choices for the respective models.

Categorical selectors

Within the categorical selectors, a clear distinction exists between multi-option and single-option selectors. For instance, the Checklist functions as a multi-option selector by default while the RadioItem serves as a single-option selector by default. However, the Dropdown can function as both a multi-option or single-option selector.

For more information, refer to the API reference of the selector, or the documentation of its underlying Dash component:

If you have binary data (such as False/True or 0/1), you might prefer to use a dedicated boolean selector instead.

Configuring options

When configuring the options of the categorical selectors, you can either give:

  • a list of values options = ['Value A', 'Value B', 'Value C']
  • or a dictionary of label-value mappings options=[{'label': 'True', 'value': True}, {'label': 'False', 'value': False}]

The later is required if you want to provide different display labels to your option values or in case you want to provide boolean values as options. In this case, you need to provide a string label for your boolean values as boolean values cannot be displayed properly as labels in the underlying Dash components.

Numerical selectors

For more information, refer to the API reference of the selector, or the documentation of its underlying Dash component:

Using float values and step with an integer value

When configuring the Slider and the RangeSlider with float values, and using step with an integer value, you may notice unexpected behavior, such as the drag value being outside its indicated marks. To our knowledge, this is a current bug in the underlying dcc.Slider and dcc.RangeSlider component, which you can circumvent by adapting the step size as needed.

Temporal selectors

For more information, refer to the API reference of the selector, or the documentation of its underlying Dash component:

Note

When configuring the DatePicker make sure to provide your dates for min, max and value arguments in "yyyy-mm-dd" format or as datetime type (for example, datetime.datetime(2024, 01, 01)).

Boolean selectors

For more information, refer to the API reference of the selector, or the documentation of its underlying Dash component:

Add a tooltip

The description argument enables you to add helpful context to your selector by displaying an info icon next to its title. Hovering over the icon shows a tooltip with your provided text.

You can provide Markdown text as a string to use the default info icon or a Tooltip model to use any icon from the Google Material Icons library.

Selectors with tooltip

import vizro.models as vm
import vizro.plotly.express as px
from vizro import Vizro

iris = px.data.iris()

page = vm.Page(
    title="Selectors with icons",
    components=[
        vm.Graph(
            figure=px.scatter(iris, x="sepal_length", y="sepal_width")
        ),
    ],
    controls=[
        vm.Filter(
            column="species",
            selector=vm.Checklist(
                title="Select Species",
                description="""
                    Select which species of iris you like.

                    [Click here](https://en.wikipedia.org/wiki/Iris_flower_data_set)
                    to learn more about flowers.""",
            )
        ),
    ]
)

dashboard = vm.Dashboard(pages=[page])
Vizro().build(dashboard).run()

Run and edit this code in Py.Cafe

pages:
  - title: Selectors with icons
    components:
      - type: graph
        figure:
          _target_: scatter
          data_frame: iris
          x: sepal_length
          y: sepal_width
    controls:
      - column: species
        type: filter
        selector:
          type: checklist
          title: Select Species
          description: |
                Select which species of iris you like.

                [Click here](https://en.wikipedia.org/wiki/Iris_flower_data_set) to learn more about flowers.

InfoIconSelector

The extra argument

Currently each selector is based on an underlying Dash component as mentioned in the sections above. Using the extra argument you can pass extra arguments to the underlying object in order to alter it beyond the chosen defaults. The available arguments can be found in the documentation of each underlying component that was linked in the respective sections above.

Note

Using extra is a quick and flexible way to alter a component beyond what Vizro offers. However, it is not a part of the official Vizro schema and the underlying implementation details may change. If you want to guarantee that your apps keep running, we recommend that you pin your Vizro version.

An example would be to make the RadioItem display inline instead of stacked vertically. For this you can use extra={"inline": True} argument:

Inline Radio Items

import vizro.models as vm
import vizro.plotly.express as px
from vizro import Vizro

iris = px.data.iris()

page = vm.Page(
    title="Inline Radio Items",
    components=[
        vm.Graph(
            figure=px.scatter(iris, x="sepal_length", y="sepal_width")
        ),
    ],
    controls=[
        vm.Filter(
            column="species",
            selector=vm.RadioItems(
                title="Select Species",
                extra={"inline": True}
            )
        )
    ]
)

dashboard = vm.Dashboard(pages=[page])
Vizro().build(dashboard).run()

Run and edit this code in Py.Cafe

pages:
  - title: Inline Radio Items
    components:
      - type: graph
        figure:
          _target_: scatter
          data_frame: iris
          x: sepal_length
          y: sepal_width
    controls:
      - column: species
        type: filter
        selector:
          type: radio_items
          title: Select Species
          extra:
            inline: true

InlineRadio