Renders a histogram to visualize the spread of a dataset based on bins representing buckets, or sub-ranges, of data. Each bin is defined by a minimum and maximum value and a total count.
You can generate the underlying histogram's bins with the histogram module. In this scenario, you can use the fromHistogramResult() helper method to conveniently create the histogram from the result object.
const params = {
layer: povLayer,
field: "POP_POVERTY",
normalizationField: "TOTPOP_CY",
numBins: 30
};
histogram(params)
.then(function(histogramResult) {
const histogram = Histogram.fromHistogramResult(histogramResult);
histogram.container = "histogram";
})
.catch(function(error) {
console.log("there was an error: ", error);
});
Other properties of this widget allow to display meaningful values on the histogram, such as the average and the dataLines properties.
See the image below for a summary of the configurable options available on this slider.
The barCreatedFunction property may be used to style the histogram bins based on the color of features in the renderer of a layer associated with the histogram.
- See also
Constructors
-
new Histogram(properties)
-
Parameterproperties Objectoptional
See the properties for a list of all the properties that may be passed into the constructor.
Example// typical usage const histogram = new Histogram({ bins: [{ minValue: 0, maxValue: 20, count: 1 }, { minValue: 21, maxValue: 40, count: 60 },{ minValue: 41, maxValue: 60, count: 239 },{ minValue: 61, maxValue: 80, count: 88 },{ minValue: 81, maxValue: 100, count: 20 }], max: 100, min: 0, average: 44 });
Property Overview
Name | Type | Summary | Class |
---|---|---|---|
Number | The statistical average of the data in the histogram. more details | Histogram | |
BarCreatedFunction | Function for styling bars representing histogram bins. more details | Histogram | |
Bin[] | An array of objects representing each bin in the histogram. more details | Histogram | |
String|HTMLElement | The ID or node representing the DOM element containing the widget. more details | Widget | |
DataLineCreatedFunction | Function that fires each time a data line is created. more details | Histogram | |
Object[] | When set, renders lines on the histogram that indicate important or meaningful values to the end user. more details | Histogram | |
String | The name of the class. more details | Accessor | |
String | The unique ID assigned to the widget when the widget is created. more details | Widget | |
String | The widget's default label. more details | Histogram | |
LabelFormatter | A function used to format labels on the histogram. more details | Histogram | |
String | Determines the orientation of the Histogram widget. more details | Histogram | |
Number | The maximum value or bound of the entire histogram. more details | Histogram | |
Number | The minimum value or bound of the entire histogram. more details | Histogram | |
String | The state of the widget. more details | Histogram | |
HistogramViewModel | The view model for the Histogram widget. more details | Histogram | |
Boolean | Indicates whether the widget is visible. more details | Widget |
Property Details
-
average Number
-
The statistical average of the data in the histogram. You would typically get this value from the
avg
property of SummaryStatisticsResult, which is the result of the summaryStatistics function.When set, this value will render on the histogram with a symbol indicating it is the average.
- See also
Examples// sets result returned from a smart mapping method // to the histogram histogram.average = response.statistics.avg;
histogram.average = 34.5;
-
barCreatedFunction BarCreatedFunction
-
Function for styling bars representing histogram bins. This can be used to color bins with the same color of features in the view that fall into bins representing the same range of data.
Examplehistogram.barCreatedFunction = function(index, element){ let bin = histogram.bins[index]; let midValue = ((bin.maxValue - bin.minValue) / 2) + bin.minValue; // colors the histogram bins with a custom function // (not defined here for brevity of the snippet) for interpolating // colors from data values to match the legend let color = getColorFromValue(midValue); element.setAttribute("fill", color.toHex()); };
-
An array of objects representing each bin in the histogram. This information is typically returned from the histogram function.
Examples// sets the bins of the histogram from the bins in the histogram() result histogram.bins = histogramResult.bins;
// Creates a histogram with 7 bins. histogram.bins = [ { minValue: 0, maxValue: 10, count: 4 }, { minValue: 10.1, maxValue: 20, count: 14 }, { minValue: 20.1, maxValue: 30, count: 9 }, { minValue: 30.1, maxValue: 40, count: 34 }, { minValue: 40.1, maxValue: 50, count: 351 }, { minValue: 50.1, maxValue: 60, count: 100 }, { minValue: 60.1, maxValue: 70, count: 1 } ];
-
-
The ID or node representing the DOM element containing the widget. This property can only be set once. The following examples are all valid use cases when working with widgets.
Examples// Create the HTML div element programmatically at runtime and set to the widget's container const basemapGallery = new BasemapGallery({ view: view, container: document.createElement("div") }); // Add the widget to the top-right corner of the view view.ui.add(basemapGallery, { position: "top-right" });
// Specify an already-defined HTML div element in the widget's container const basemapGallery = new BasemapGallery({ view: view, container: basemapGalleryDiv }); // Add the widget to the top-right corner of the view view.ui.add(basemapGallery, { position: "top-right" }); // HTML markup <body> <div id="viewDiv"></div> <div id="basemapGalleryDiv"></div> </body>
// Specify the widget while adding to the view's UI const basemapGallery = new BasemapGallery({ view: view }); // Add the widget to the top-right corner of the view view.ui.add(basemapGallery, { position: "top-right" });
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dataLineCreatedFunction DataLineCreatedFunction
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Function that fires each time a data line is created. You can use this to style individual dataLines on the data axis.
Examplehistogram.dataLineCreatedFunction = function (lineElement, labelElement, index) { lineElement.setAttribute("y2", "25%"); lineElement.classList.add("line-style"); };
-
When set, renders lines on the histogram that indicate important or meaningful values to the end user.
- Properties
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value Number
The value on the data axis of the histogram where a line will be rendered.
optional The label associated with the line.
Examples// will render lines at the 25th, 50th, 75th, and 99th percentiles histogram.dataLines = [{ value: 30, label: "25 pctl" }, { value: 45, label: "50 pctl" }, { value: 65, label: "75 pctl" }, { value: 89, label: "99 pctl" }];
// calculate standard deviations from mean using stats // returned from smart mapping statistic methods const stddevs = smartMappingUtils.getDeviationValues(stats.stddev, stats.avg, 2); histogram.dataLines = stddevs.map(function(stddev){ return { value: stddev }; });
-
The name of the class. The declared class name is formatted as
esri.folder.className
.
-
The unique ID assigned to the widget when the widget is created. If not set by the developer, it will default to the container ID, or if that is not present then it will be automatically generated.
-
label String
-
The widget's default label. This label displays when it is used within another widget, such as the Expand or LayerList widgets.
-
labelFormatFunction LabelFormatter
-
A function used to format labels on the histogram. Overrides the default label formatter.
Example// For thumb values, rounds each label to whole numbers. slider.labelFormatFunction = function(value) { return value.toFixed(0); }
-
layout String
-
Determines the orientation of the Histogram widget.
Possible Values:"vertical"|"horizontal"
- Default Value:horizontal
Examplehistogram.layout = "vertical";
-
max Number
-
The maximum value or bound of the entire histogram. This should match the maximum bound of the last bin.
Exampleshistogram.max = 100;
// sets result returned from a smart mapping method // to the histogram histogram.max = response.statistics.max;
-
min Number
-
The minimum value or bound of the entire histogram. This should match the minimum bound of the first bin.
Exampleshistogram.min = 0;
// sets result returned from a smart mapping method // to the histogram histogram.min = response.statistics.min;
-
state Stringreadonly
-
The state of the widget.
Possible Values:"ready"|"disabled"
-
viewModel HistogramViewModel
-
The view model for the Histogram widget. This is a class that contains all the logic (properties and methods) that controls this widget's behavior. See the HistogramViewModel class to access all properties and methods on the Histogram widget.
-
Indicates whether the widget is visible.
If
false
, the widget will no longer be rendered in the web document. This may affect the layout of other elements or widgets in the document. For example, if this widget is the first of three widgets associated to the upper right hand corner of the view UI, then the other widgets will reposition when this widget is made invisible. For more information, refer to the CSS display value of"none"
.- Default Value:true
Example// Hides the widget in the view widget.visible = false;
Method Overview
Name | Return Type | Summary | Class |
---|---|---|---|
Adds one or more handles which are to be tied to the lifecycle of the object. more details | Accessor | ||
String | A utility method used for building the value for a widget's | Widget | |
Destroys the widget instance. more details | Widget | ||
Boolean | Emits an event on the instance. more details | Widget | |
Histogram | A convenience function used to create a Histogram widget instance from the result of the histogram statistics function. more details | Histogram | |
Boolean | Indicates whether there is an event listener on the instance that matches the provided event name. more details | Widget | |
Boolean | Returns true if a named group of handles exist. more details | Accessor | |
Boolean |
| Widget | |
Boolean |
| Widget | |
Boolean |
| Widget | |
Object | Registers an event handler on the instance. more details | Widget | |
Adds one or more handles which are to be tied to the lifecycle of the widget. more details | Widget | ||
This method is primarily used by developers when implementing custom widgets. more details | Widget | ||
Removes a group of handles owned by the object. more details | Accessor | ||
Object | This method is primarily used by developers when implementing custom widgets. more details | Widget | |
Renders widget to the DOM immediately. more details | Widget | ||
This method is primarily used by developers when implementing custom widgets. more details | Widget | ||
Promise |
| Widget |
Method Details
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addHandles(handleOrHandles, groupKey)inheritedSince: ArcGIS Maps SDK for JavaScript 4.25
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Adds one or more handles which are to be tied to the lifecycle of the object. The handles will be removed when the object is destroyed.
// Manually manage handles const handle = reactiveUtils.when( () => !view.updating, () => { wkidSelect.disabled = false; }, { once: true } ); this.addHandles(handle); // Destroy the object this.destroy();
ParametershandleOrHandles WatchHandle|WatchHandle[]Handles marked for removal once the object is destroyed.
groupKey *optionalKey identifying the group to which the handles should be added. All the handles in the group can later be removed with Accessor.removeHandles(). If no key is provided the handles are added to a default group.
-
A utility method used for building the value for a widget's
class
property. This aids in simplifying CSS class setup.Parameterrepeatable The class names.
ReturnsType Description String The computed class name. Example// .tsx syntax showing how to set CSS classes while rendering the widget render() { const dynamicIconClasses = { [CSS.myIcon]: this.showIcon, [CSS.greyIcon]: !this.showIcon }; return ( <div class={classes(CSS.root, CSS.mixin, dynamicIconClasses)} /> ); }
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destroy()inherited
-
Destroys the widget instance.
-
Emits an event on the instance. This method should only be used when creating subclasses of this class.
Parameterstype StringThe name of the event.
event ObjectoptionalThe event payload.
ReturnsType Description Boolean true
if a listener was notified
-
-
A convenience function used to create a Histogram widget instance from the result of the histogram statistics function.
Parameterresult HistogramResultThe result of the histogram statistics function used to generate a histogram for a field or expression from a layer.
ReturnsType Description Histogram The histogram instance representing the histogram returned from histogram. Examplelet colorParams = { layer: povLayer, basemap: map.basemap, field: "POP_POVERTY", normalizationField: "TOTPOP_CY", theme: "above-and-below" }; let stats = null; colorRendererCreator .createContinuousRenderer(colorParams) .then(function(response) { // set the renderer to the layer and add it to the map stats = response.statistics; return histogram({ layer: povLayer, field: "POP_POVERTY", normalizationField: "TOTPOP_CY", numBins: 100 }); }) .then(function(histogramResult) { let histogram = Histogram.fromHistogramResult(histogramResult); histogram.container = "histogram"; histogram.average = stats.avg; }) .catch(function(error) { console.log("there was an error: ", error); });
-
Indicates whether there is an event listener on the instance that matches the provided event name.
Parametertype StringThe name of the event.
ReturnsType Description Boolean Returns true if the class supports the input event.
-
Since: ArcGIS Maps SDK for JavaScript 4.25
-
Returns true if a named group of handles exist.
ParametergroupKey *optionalA group key.
ReturnsType Description Boolean Returns true
if a named group of handles exist.Example// Remove a named group of handles if they exist. if (obj.hasHandles("watch-view-updates")) { obj.removeHandles("watch-view-updates"); }
-
Since: ArcGIS Maps SDK for JavaScript 4.19
-
isFulfilled()
may be used to verify if creating an instance of the class is fulfilled (either resolved or rejected). If it is fulfilled,true
will be returned.ReturnsType Description Boolean Indicates whether creating an instance of the class has been fulfilled (either resolved or rejected).
-
Since: ArcGIS Maps SDK for JavaScript 4.19
-
isRejected()
may be used to verify if creating an instance of the class is rejected. If it is rejected,true
will be returned.ReturnsType Description Boolean Indicates whether creating an instance of the class has been rejected.
-
Since: ArcGIS Maps SDK for JavaScript 4.19
-
isResolved()
may be used to verify if creating an instance of the class is resolved. If it is resolved,true
will be returned.ReturnsType Description Boolean Indicates whether creating an instance of the class has been resolved.
-
Registers an event handler on the instance. Call this method to hook an event with a listener.
ParametersAn event or an array of events to listen for.
listener FunctionThe function to call when the event fires.
ReturnsType Description Object Returns an event handler with a remove()
method that should be called to stop listening for the event(s).Property Type Description remove Function When called, removes the listener from the event. Exampleview.on("click", function(event){ // event is the event handle returned after the event fires. console.log(event.mapPoint); });
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own(handleOrHandles)inheritedSince: ArcGIS Maps SDK for JavaScript 4.24
-
Adds one or more handles which are to be tied to the lifecycle of the widget. The handles will be removed when the widget is destroyed.
const handle = reactiveUtils.when( () => !view.updating, () => { wkidSelect.disabled = false; }, { once: true} ); this.own(handle); // Handle gets removed when the widget is destroyed.
ParameterhandleOrHandles WatchHandle|WatchHandle[]Handles marked for removal once the widget is destroyed.
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postInitialize()inherited
-
This method is primarily used by developers when implementing custom widgets. Executes after widget is ready for rendering.
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removeHandles(groupKey)inheritedSince: ArcGIS Maps SDK for JavaScript 4.25
-
Removes a group of handles owned by the object.
ParametergroupKey *optionalA group key or an array or collection of group keys to remove.
Exampleobj.removeHandles(); // removes handles from default group obj.removeHandles("handle-group"); obj.removeHandles("other-handle-group");
-
This method is primarily used by developers when implementing custom widgets. It must be implemented by subclasses for rendering.
ReturnsType Description Object The rendered virtual node.
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renderNow()inherited
-
Renders widget to the DOM immediately.
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scheduleRender()inherited
-
This method is primarily used by developers when implementing custom widgets. Schedules widget rendering. This method is useful for changes affecting the UI.
-
Since: ArcGIS Maps SDK for JavaScript 4.19
-
when()
may be leveraged once an instance of the class is created. This method takes two input parameters: acallback
function and anerrback
function. Thecallback
executes when the instance of the class loads. Theerrback
executes if the instance of the class fails to load.Parameterscallback FunctionoptionalThe function to call when the promise resolves.
errback FunctionoptionalThe function to execute when the promise fails.
ReturnsType Description Promise Returns a new promise for the result of callback
.Example// Although this example uses the BasemapGallery widget, any class instance that is a promise may use when() in the same way let bmGallery = new BasemapGallery(); bmGallery.when(function(){ // This function will execute once the promise is resolved }, function(error){ // This function will execute if the promise is rejected due to an error });
Type Definitions
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BarCreatedFunction(index, element)
-
Function used to style or attach custom interaction to histogram bars. This function should be set to the barCreatedFunction property. It fires for each bar when it is created.
Parametersindex NumberThe index of the histogram bar. This directly corresponds to the index of the associated bin.
element SVGElementThe histogram bar element to style.
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Bin
-
Represents the bin of a histogram. A bin consists of a minimum and a maximum value and a count. It indicates the number of values in a dataset that lie between the min and max values.
-
DataLineCreatedFunction(lineElement, labelElement, index)
-
Function used to style dataLines. This function should be set to the dataLineCreatedFunction property. It fires when each data line is created.
ParameterslineElement SVGElementThe SVG element representing the data line rendered on the histogram.
labelElement SVGElementoptionalThe SVG element representing the label rendered on the histogram for the associated line element.
index NumberoptionalThe index of the data line.
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LabelFormatter(value, type, index){String}
-
Function used to format labels. This function should be set to the labelFormatFunction property. This function fires every time a label is created or updated on the histogram.
Parametersvalue NumberThe value for the line on the data axis.
type StringoptionalThe label type. Currently, the only supported type is
average
.index NumberoptionalThe index of the data line (or value).
ReturnsType Description String The formatted value of the label.