An example of a basic slider tied to a callback.
import dash
import dash_html_components as html
import dash_core_components as dcc
external_stylesheets = ['https://codepen.io/chriddyp/pen/bWLwgP.css']
app = dash.Dash(__name__, external_stylesheets=external_stylesheets)
app.layout = html.Div([
dcc.Slider(
id='my-slider',
min=0,
max=20,
step=0.5,
value=10,
),
html.Div(id='slider-output-container')
])
@app.callback(
dash.dependencies.Output('slider-output-container', 'children'),
[dash.dependencies.Input('my-slider', 'value')])
def update_output(value):
return 'You have selected "{}"'.format(value)
if __name__ == '__main__':
app.run_server(debug=True)
If slider marks are defined and step is set to None then the slider will only be able to select values that have been predefined by the marks. Note that the default is step=1, so you must explicitly specify None to get this behavior.marks is a dict where the keys represent the numerical values and the values represent their labels.
import dash_core_components as dcc
dcc.Slider(
min=0,
max=10,
step=None,
marks={
0: '0 °F',
3: '3 °F',
5: '5 °F',
7.65: '7.65 °F',
10: '10 °F'
},
value=5
)
By default, included=True, meaning the rail trailing the handle will be highlighted. To have the handle act as a discrete value set included=False. To style marks, include a style css attribute alongside the key value.
import dash_core_components as dcc
# Slider has included=True by default
dcc.Slider(
min=0,
max=100,
value=65,
marks={
0: {'label': '0 °C', 'style': {'color': '#77b0b1'}},
26: {'label': '26 °C'},
37: {'label': '37 °C'},
100: {'label': '100 °C', 'style': {'color': '#f50'}}
}
)
import dash_core_components as dcc
dcc.Slider(
min=0,
max=100,
value=65,
marks={
0: {'label': '0 °C', 'style': {'color': '#77b0b1'}},
26: {'label': '26 °C'},
37: {'label': '37 °C'},
100: {'label': '100 °C', 'style': {'color': '#f50'}}
},
included=False
)
Create a logarithmic slider by setting the labels of the marks property to be logarithmic and adjusting the slider’s output value in the callbacks. The updatemode property allows us to determine when we want a callback to be triggered. The following example has updatemode='drag' which means a callback is triggered everytime the handle is moved. The default setting is mouseup which triggers the callback when you release your mouse from the slider.
import dash_core_components as dcc
import dash_html_components as html
from dash.dependencies import Input, Output
import dash
external_stylesheets = ['https://codepen.io/chriddyp/pen/bWLwgP.css']
app = dash.Dash(__name__, external_stylesheets=external_stylesheets)
# Use the following function when accessing the value of 'my-slider'
# in callbacks to transform the output value to logarithmic
def transform_value(value):
return 10 ** value
app.layout = html.Div([
dcc.Slider(
id='slider-updatemode',
marks={i: '{}'.format(10 ** i) for i in range(4)},
max=3,
value=2,
step=0.01,
updatemode='drag'
),
html.Div(id='updatemode-output-container', style={'margin-top': 20})
])
@app.callback(Output('updatemode-output-container', 'children'),
Input('slider-updatemode', 'value'))
def display_value(value):
return 'Linear Value: {} | \
Log Value: {:0.2f}'.format(value, transform_value(value))
if __name__ == '__main__':
app.run_server(debug=True)
Rather than changing the updatemode of the slider, you can also use drag_value an an input. This makes it possible to react differently to drag and mouseup.
import dash_core_components as dcc
import dash_html_components as html
from dash.dependencies import Input, Output
import dash
external_stylesheets = ['https://codepen.io/chriddyp/pen/bWLwgP.css']
app = dash.Dash(__name__, external_stylesheets=external_stylesheets)
app.layout = html.Div([
dcc.Slider(id='slider-drag'),
html.Div(id='slider-drag-output', style={'margin-top': 20})
])
@app.callback(Output('slider-drag-output', 'children'),
[Input('slider-drag', 'drag_value'), Input('slider-drag', 'value')])
def display_value(drag_value, value):
return 'drag_value: {} | value: {}'.format(drag_value, value)
if __name__ == '__main__':
app.run_server(debug=True)
Access this documentation in your Python terminal with:
```pythonhelp(dash_core_components.Slider)
```Our recommended IDE for writing Dash apps is Dash Enterprise’s
Data Science Workspaces,
which has typeahead support for Dash Component Properties.
Find out if your company is using
Dash Enterprise.
id (string; optional):
The ID of this component, used to identify dash components in
callbacks. The ID needs to be unique across all of the components
in an app.
className (string; optional):
Additional CSS class for the root DOM node.
disabled (boolean; optional):
If True, the handles can’t be moved.
dots (boolean; optional):
When the step value is greater than 1, you can set the dots to
True if you want to render the slider with dots.
drag_value (number; optional):
The value of the input during a drag.
included (boolean; optional):
If the value is True, it means a continuous value is included.
Otherwise, it is an independent value.
loading_state (dict; optional):
Object that holds the loading state object coming from
dash-renderer.
loading_state is a dict with keys:
component_name (string; optional):
Holds the name of the component that is loading.
is_loading (boolean; optional):
Determines if the component is loading or not.
prop_name (string; optional):
Holds which property is loading.
marks (dict; optional):
Marks on the slider. The key determines the position (a number),
and the value determines what will show. If you want to set the
style of a specific mark point, the value should be an object
which contains style and label properties.
marks is a dict with strings as keys and values of type string |
dict with keys:
label (string; optional)
style (dict; optional)
max (number; optional):
Maximum allowed value of the slider.
min (number; optional):
Minimum allowed value of the slider.
persisted_props (list of a value equal to: ‘value’s; default \['value'\]):
Properties whose user interactions will persist after refreshing
the component or the page. Since only value is allowed this prop
can normally be ignored.
persistence (boolean | string | number; optional):
Used to allow user interactions in this component to be persisted
when the component - or the page - is refreshed. If persisted is
truthy and hasn’t changed from its previous value, a value that
the user has changed while using the app will keep that change, as
long as the new value also matches what was given originally.
Used in conjunction with persistence_type.
persistence_type (a value equal to: ‘local’, ‘session’, ‘memory’; default 'local'):
Where persisted user changes will be stored: memory: only kept in
memory, reset on page refresh. local: window.localStorage, data is
kept after the browser quit. session: window.sessionStorage, data
is cleared once the browser quit.
step (number; optional):
Value by which increments or decrements are made.
tooltip (dict; optional):
Configuration for tooltips describing the current slider value.
tooltip is a dict with keys:
always_visible (boolean; optional):
Determines whether tooltips should always be visible (as
opposed to the default, visible on hover).
placement (a value equal to: ‘left’, ‘right’, ‘top’, ‘bottom’, ‘topLeft’, ‘topRight’, ‘bottomLeft’, ‘bottomRight’; optional):
Determines the placement of tooltips See
https://github.com/react-component/tooltip#api top/bottom{*}
sets the origin of the tooltip, so e.g. topLeft will in
reality appear to be on the top right of the handle.
updatemode (a value equal to: ‘mouseup’, ‘drag’; default 'mouseup'):
Determines when the component should update its value property.
If mouseup (the default) then the slider will only trigger its
value when the user has finished dragging the slider. If drag,
then the slider will update its value continuously as it is being
dragged. If you want different actions during and after drag,
leave updatemode as mouseup and use drag_value for the
continuously updating value.
value (number; optional):
The value of the input.
vertical (boolean; optional):
If True, the slider will be vertical.
verticalHeight (number; default 400):
The height, in px, of the slider if it is vertical.