Interactive Visualizations
This is the 3rd chapter of the Dash Fundamentals.
The previous chapter covered basic callback usage. The next chapter describes how to share data between callbacks. Just getting started? Make sure to install the necessary dependencies.
The Dash.NET.DCC module includes a Graph component called DCC.Graph.graph.
DCC.Graph.graph renders interactive data visualizations using the open source plotly.js JavaScript graphing library. Plotly.js supports over 35 chart types and renders charts in both vector-quality SVG and high-performance WebGL.
The figure attribute in the DCC.Graph.graph component is the same figure argument that is used by Plotly.NET. Check out the Plotly.NET documentation and gallery to learn more.
As we already saw, Dash components are described by a set of attributes.
Any of these attributes can be updated by callback functions, but only
a subset of these attributes are updated through user interaction, such as
typing inside a DCC.Input.input component or clicking an option
in a DCC.Dropdown.dropdown component.
The DCC.Graph.graph component has four attributes that can change
through user-interaction: hoverData, clickData, selectedData,
relayoutData. These properties update when you hover over points, click on points, or
select regions of points in a graph.
Here’s an example that prints these attributes to the screen.
Show code
Show code
open Dash.NET
open Dash.NET.DCC
open Plotly.NET
open Newtonsoft.Json
let xDataA = [1;2]
let yDataA = [1;2]
let fruitA = ["apple"; "apple"]
let xDataB = [1;2]
let yDataB = [3;4]
let fruitB = ["orange"; "orange"]
let fig =
[ Chart.Scatter(xDataA, yDataA, StyleParam.Mode.Markers, Color = Color.fromKeyword Red, Labels = fruitA)
Chart.Scatter(xDataB, yDataB, StyleParam.Mode.Markers, Color = Color.fromKeyword Orange, Labels = fruitB) ]
|> Chart.combine
|> GenericChart.toFigure
let dslLayout =
Html.div [
Attr.children [
Graph.graph "basic-interactions" [
Graph.Attr.figure fig
]
Html.div [
Attr.className "row"
Attr.children [
Html.div [
Attr.className "three columns"
Attr.children [
Markdown.markdown "hover-data-head" [
Markdown.Attr.children "
**Hover Data**
Mouse over values in the graph.
"
]
Html.pre [
Attr.id "hover-data"
Attr.style [
Css.border ("thin", Feliz.borderStyle.solid, "lightgrey")
Css.overflowXScroll
]
]
]
]
Html.div [
Attr.className "three columns"
Attr.children [
Markdown.markdown "click-data-head" [
Markdown.Attr.children "
**Click Data**
Click on points in the graph.
"
]
Html.pre [
Attr.id "click-data"
Attr.style [
Css.border ("thin", Feliz.borderStyle.solid, "lightgrey")
Css.overflowXScroll
]
]
]
]
Html.div [
Attr.className "three columns"
Attr.children [
Markdown.markdown "selected-data-head" [
Markdown.Attr.children "
**Selection Data**
Choose the lasso or rectangle tool in the graph's menu
bar and then select points in the graph.
Note that if `layout.clickmode = 'event+select'`, selection data also
accumulates (or un-accumulates) selected data if you hold down the shift
button while clicking.
"
]
Html.pre [
Attr.id "selected-data"
Attr.style [
Css.border ("thin", Feliz.borderStyle.solid, "lightgrey")
Css.overflowXScroll
]
]
]
]
Html.div [
Attr.className "three columns"
Attr.children [
Markdown.markdown "relayout-data-head" [
Markdown.Attr.children "
**Zoom and Relayout Data**
Click and drag on the graph to zoom or click on the zoom
buttons in the graph's menu bar.
Clicking on legend items will also fire
this event.
"
]
Html.pre [
Attr.id "relayout-data"
Attr.style [
Css.border ("thin", Feliz.borderStyle.solid, "lightgrey")
Css.overflowXScroll
]
]
]
]
]
]
]
]
let hoverDataCallback =
Callback.singleOut(
"basic-interactions" @. (CustomProperty "hoverData"),
"hover-data" @. Children,
fun (data: obj) ->
"hover-data" @. Children => JsonConvert.SerializeObject(data, Formatting.Indented)
)
let clickDataCallback =
Callback.singleOut(
"basic-interactions" @. (CustomProperty "clickData"),
"click-data" @. Children,
fun (data: obj) ->
"click-data" @. Children => JsonConvert.SerializeObject(data, Formatting.Indented)
)
let selectedDataCallback =
Callback.singleOut(
"basic-interactions" @. (CustomProperty "selectedData"),
"selected-data" @. Children,
fun (data: obj) ->
"selected-data" @. Children => JsonConvert.SerializeObject(data, Formatting.Indented)
)
let relayoutDataCallback =
Callback.singleOut(
"basic-interactions" @. (CustomProperty "relayoutData"),
"relayout-data" @. Children,
fun (data: obj) ->
"relayout-data" @. Children => JsonConvert.SerializeObject(data, Formatting.Indented)
)
[<EntryPoint>]
let main args =
Giraffe.DashApp.initDefault()
|> Giraffe.DashApp.withLayout dslLayout
|> Giraffe.DashApp.appendCSSLinks ["https://codepen.io/chriddyp/pen/bWLwgP.css"]
|> Giraffe.DashApp.addCallbacks [
hoverDataCallback
clickDataCallback
selectedDataCallback
relayoutDataCallback
]
|> Giraffe.DashApp.run args (Giraffe.DashGiraffeConfig.initDebug "localhost")
Hover Data
Mouse over values in the graph.
Click Data
Click on points in the graph.
Selection Data
Choose the lasso or rectangle tool in the graph’s menu
bar and then select points in the graph.
Note that if layout.clickmode = 'event+select', selection data also
accumulates (or un-accumulates) selected data if you hold down the shift
button while clicking.
Zoom and Relayout Data
Click and drag on the graph to zoom or click on the zoom
buttons in the graph’s menu bar.
For optimal user interaction and chart loading performance, Dash apps
in production should consider the Job Queue,
HPC, Datashader,
and horizontal scaling capabilities of Dash Enterprise.
Update Graphs on Hover
Let’s update our world indicators example from the previous chapter by updating the time series when we hover over points in our scatter plot.
Show code
Show code
open Dash.NET
open Dash.NET.DCC
open Plotly.NET
open FSharp.Data
let df = CsvFile.Load("https://plotly.github.io/datasets/country_indicators.csv").Rows |> List.ofSeq
let available_indicators = df |> List.map (fun r -> r.Item "Indicator Name") |> List.distinct
let dslLayout =
Html.div [
Attr.children [
Html.div [
Attr.children [
Html.div [
Attr.children [
Dropdown.dropdown "crossfilter-xaxis-column" [
Dropdown.Attr.options <| List.map (fun ai -> DropdownOption.init(label = ai, value = ai)) available_indicators
Dropdown.Attr.value "Fertility rate, total (births per woman)"
]
RadioItems.radioItems "crossfilter-xaxis-type" [
RadioItems.Attr.options [
RadioItemsOption.init(label = "Linear", value = "Linear")
RadioItemsOption.init(label = "Log", value = "Log")
]
RadioItems.Attr.value "Linear"
RadioItems.Attr.labelStyle [
Css.displayInlineBlock
Css.marginTop (Feliz.length.px 5)
]
]
]
Attr.style [
Css.displayInlineBlock
Css.width (Feliz.length.perc 49)
]
]
Html.div [
Attr.children [
Dropdown.dropdown "crossfilter-yaxis-column" [
Dropdown.Attr.options <| List.map (fun ai -> DropdownOption.init(label = ai, value = ai)) available_indicators
Dropdown.Attr.value "Life expectancy at birth, total (years)"
]
RadioItems.radioItems "crossfilter-yaxis-type" [
RadioItems.Attr.options [
RadioItemsOption.init(label = "Linear", value = "Linear")
RadioItemsOption.init(label = "Log", value = "Log")
]
RadioItems.Attr.value "Linear"
RadioItems.Attr.labelStyle [
Css.displayInlineBlock
Css.marginTop (Feliz.length.px 5)
]
]
]
Attr.style [
Css.displayInlineBlock
Css.width (Feliz.length.perc 49)
]
]
]
Attr.style [
Css.padding (Feliz.length.px 10, Feliz.length.px 5)
]
]
Html.div [
Attr.children [
Graph.graph "crossfilter-indicator-scatter" [
Graph.Attr.hoverData {| points = [{| text = "Japan" |}] |}
]
]
Attr.style [
Css.width (Feliz.length.perc 49)
Css.displayInlineBlock
Css.padding (Feliz.length.px 0, Feliz.length.px 20)
]
]
Html.div [
Attr.children [
Graph.graph "x-time-series" []
Graph.graph "y-time-series" []
]
Attr.style [
Css.width (Feliz.length.perc 49)
Css.displayInlineBlock
]
]
Html.div [
Attr.children [
Slider.slider "crossfilter-year-slider" [
let years = df |> List.map (fun r -> r.Item "Year")
yield Slider.Attr.min (years |> List.map int |> List.min)
yield Slider.Attr.max (years |> List.map int |> List.max)
yield Slider.Attr.value (years |> List.map int |> List.max)
yield Slider.Attr.marks (
years
|> List.map (fun y -> (y, Slider.MarkValue.String y))
|> Map.ofList
|> Slider.MarksType
)
yield Slider.Attr.step null
]
]
Attr.style [
Css.width (Feliz.length.perc 49)
Css.padding (Feliz.length.px 0, Feliz.length.px 20, Feliz.length.px 20, Feliz.length.px 20)
]
]
]
]
let updateGraph =
Callback.multiOut(
[ "crossfilter-xaxis-column" @. Value
"crossfilter-yaxis-column" @. Value
"crossfilter-xaxis-type" @. Value
"crossfilter-yaxis-type" @. Value
"crossfilter-year-slider" @. Value ],
[ "crossfilter-indicator-scatter" @. (CustomProperty "figure") ],
fun xAxisColumnName yAxisColumnName xAxisType yAxisType yearValue ->
let dff = df |> List.filter (fun r -> r.Item "Year" = yearValue)
let xRows = dff |> List.filter (fun r -> r.Item "Indicator Name" = xAxisColumnName)
let yRows = dff |> List.filter (fun r -> r.Item "Indicator Name" = yAxisColumnName)
let xData = xRows |> List.map (fun r -> r.Item "Value")
let yData = yRows |> List.map (fun r -> r.Item "Value")
let yLabels = yRows |> List.map (fun r -> r.Item "Country Name")
let fig =
Chart.Scatter(xData, yData, StyleParam.Mode.Markers, Labels = yLabels)
|> Chart.withXAxis(
LayoutObjects.LinearAxis.init(
AxisType = (if xAxisType = "Linear" then StyleParam.AxisType.Linear else StyleParam.AxisType.Log),
Title = Title.init xAxisColumnName
)
)
|> Chart.withYAxis(
LayoutObjects.LinearAxis.init(
AxisType = (if yAxisType = "Linear" then StyleParam.AxisType.Linear else StyleParam.AxisType.Log),
Title = Title.init yAxisColumnName
)
)
|> Chart.withLayout (
Layout.init(
Margin = LayoutObjects.Margin.init(Left = 40, Right = 0, Top = 10, Bottom = 40),
HoverMode = StyleParam.HoverMode.Closest
)
)
|> GenericChart.toFigure
[ "crossfilter-indicator-scatter" @. (CustomProperty "figure") => fig ]
, PreventInitialCall = false
)
let createTimeSeries xData yearData axisType title =
Chart.Scatter(xData, yearData, StyleParam.Mode.Lines_Markers, Name = title)
|> Chart.withXAxis(
LayoutObjects.LinearAxis.init(
ShowGrid = false,
Title = Title.init "Value"
)
)
|> Chart.withYAxis(
LayoutObjects.LinearAxis.init(
AxisType = (if axisType = "Linear" then StyleParam.AxisType.Linear else StyleParam.AxisType.Log),
Title = Title.init "Year"
)
)
|> Chart.withLayout (
Layout.init(
Margin = LayoutObjects.Margin.init(Left = 40, Right = 0, Top = 10, Bottom = 40),
HoverMode = StyleParam.HoverMode.Closest
)
)
|> Chart.withAnnotations [
LayoutObjects.Annotation.init(
X = 0,
Y = 0.85,
XRef = "paper",
YRef = "paper",
ShowArrow = false,
XAnchor = StyleParam.XAnchorPosition.Left,
YAnchor = StyleParam.YAnchorPosition.Bottom
)
]
|> GenericChart.toFigure
type PointData =
{ text: string }
type HoverData =
{ points: PointData list}
let updateXTimeseries =
Callback.multiOut(
[ "crossfilter-xaxis-column" @. Value
"crossfilter-xaxis-type" @. Value
"crossfilter-indicator-scatter" @. (CustomProperty "hoverData") ],
[ "x-time-series" @. (CustomProperty "figure") ],
fun xAxisColumnName xAxisType (hoverData: HoverData) ->
match hoverData.points |> List.tryHead |> Option.map (fun h -> h.text) with
| None -> []
| Some countryName ->
let dff = df |> List.filter (fun r -> r.Item "Country Name" = countryName)
let rows = dff |> List.filter (fun r -> r.Item "Indicator Name" = xAxisColumnName)
let yData = rows |> List.map (fun r -> r.Item "Value")
let xData = rows |> List.map (fun r -> r.Item "Year")
let title = sprintf "<b>%s<b><br>%s" countryName xAxisColumnName
[ "x-time-series" @. (CustomProperty "figure") => createTimeSeries xData yData xAxisType title ]
, PreventInitialCall = false
)
let updateYTimeseries =
Callback.multiOut(
[ "crossfilter-yaxis-column" @. Value
"crossfilter-yaxis-type" @. Value
"crossfilter-indicator-scatter" @. (CustomProperty "hoverData") ],
[ "y-time-series" @. (CustomProperty "figure") ],
fun yAxisColumnName yAxisType (hoverData: HoverData) ->
match hoverData.points |> List.tryHead |> Option.map (fun h -> h.text) with
| None -> []
| Some countryName ->
let dff = df |> List.filter (fun r -> r.Item "Country Name" = countryName)
let rows = dff |> List.filter (fun r -> r.Item "Indicator Name" = yAxisColumnName)
let yData = rows |> List.map (fun r -> r.Item "Value")
let xData = rows |> List.map (fun r -> r.Item "Year")
let title = sprintf "<b>%s<b><br>%s" countryName yAxisColumnName
[ "y-time-series" @. (CustomProperty "figure") => createTimeSeries xData yData yAxisType title ]
, PreventInitialCall = false
)
[<EntryPoint>]
let main args =
Giraffe.DashApp.initDefault()
|> Giraffe.DashApp.withLayout dslLayout
|> Giraffe.DashApp.appendCSSLinks ["https://codepen.io/chriddyp/pen/bWLwgP.css"]
|> Giraffe.DashApp.addCallback updateGraph
|> Giraffe.DashApp.addCallbacks [
updateXTimeseries
updateYTimeseries
]
|> Giraffe.DashApp.run args (Giraffe.DashGiraffeConfig.initDebug "localhost")
Try moving the mouse over the points in the scatter plot on the left. Notice how the line graphs on the right update based on the point that you are hovering over.
As an aside, if you find yourself filtering and visualizing highly-dimensional datasets, you should consider checking out the parallel coordinates chart type.
Current Limitations
There are a few limitations in graph interactions right now.
- It is not currently possible to customize the style of the hover interactions or the select box. This issue is being worked on in https://github.com/plotly/plotly.js/issues/1847.
There’s a lot that you can do with these interactive plotting features. If you need help exploring your use case, open up a thread in the Dash Community Forum.
The next chapter of the Dash Fundamentals explains how to share data between callbacks. Dash Fundamentals Part 4. Sharing Data Between Callbacks