This sample demonstrates how to execute a geoprocessing task to calculate a hotspot analysis based on the frequency of 911 calls. It calculates the frequency of these calls within a given study area during a specified constrained time period set between 1/1/1998 and 5/31/1998.
Use case
This tool identifies statistically significant spatial clusters of high values (hot spots) and low values (cold spots). For example, a hotspot analysis based on the frequency of 911 calls within a set region.
How to use the sample
Select a date range (between 1998-01-01 and 1998-05-31) from the dialog and tap on Analyze. The results will be shown on the map upon successful completion of the GeoprocessingJob.
How it works
Create a GeoprocessingTask with the URL set to the endpoint of a geoprocessing service.
Create a query string with the date range as an input of GeoprocessingParameters.
Use the GeoprocessingTask to create a GeoprocessingJob with the GeoprocessingParameters instance.
Start the GeoprocessingJob and wait for it to complete and return a GeoprocessingResult.
Get the resulting ArcGISMapImageLayer using GeoprocessingResult.MapImageLayer.
Add the layer to the map's operational layers.
Relevant API
ArcGISMapImageLayer
GeoprocessingJob
GeoprocessingParameters
GeoprocessingResult
GeoprocessingString
GeoprocessingTask
Map
Tags
analysis, density, geoprocessing, hot spots, hotspots
Sample Code
AnalyzeHotspots.qml
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// [WriteFile Name=AnalyzeHotspots, Category=Analysis]// [Legal]// Copyright 2017 Esri.// Licensed under the Apache License, Version 2.0 (the "License");// you may not use this file except in compliance with the License.// You may obtain a copy of the License at// http://www.apache.org/licenses/LICENSE-2.0// Unless required by applicable law or agreed to in writing, software// distributed under the License is distributed on an "AS IS" BASIS,// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.// See the License for the specific language governing permissions and// limitations under the License.// [Legal]import QtQuick
import QtQuick.Controls
// import Qt.labs.calendar // Calendar is not supported in Qt 6.2import Esri.ArcGISRuntime
import QtQuick.Layouts
Rectangle {
id: rootRectangleclip: truewidth: 800height: 600property var jobproperty bool jobInProgress : falseproperty string statusText: ""property date fromThisDate : Date.fromLocaleDateString(Qt.locale(), "98/01/01", "yy/MM/dd");
property date toThisDate : Date.fromLocaleDateString(Qt.locale(), "98/01/31", "yy/MM/dd")
// Declare the MapView with a Map and BasemapMapView {
id: mapViewanchors.fill: parentComponent.onCompleted: {
// Set the focus on MapView to initially enable keyboard navigation forceActiveFocus();
}
Map {
Basemap {
initStyle: Enums.BasemapStyleArcGISTopographic
}
}
}
// Declare the GeoprocessingTask and set the URLGeoprocessingTask {
id: hotspotTaskurl: "https://sampleserver6.arcgisonline.com/arcgis/rest/services/911CallsHotspot/GPServer/911%20Calls%20Hotspot"onErrorChanged: {
if (error)
showErrorDialog(error);
}
functionrunTask() {
// Create job that handles the communication between the application and the geoprocessing task job = hotspotTask.createJob(hotspotParameters);
// Connect to the job's status changed signal job.statusChanged.connect(()=> {
if (job.jobStatus === Enums.JobStatusFailed) {
showErrorDialog(job.error);
jobInProgress = false;
statusText = "Job failed.";
} elseif (job.jobStatus === Enums.JobStatusStarted) {
jobInProgress = true;
statusText = "Job in progress...";
} elseif (job.jobStatus === Enums.JobStatusPaused) {
jobInProgress = false;
statusText = "Job paused...";
} elseif (job.jobStatus === Enums.JobStatusSucceeded) {
// handle the results processResults(job.result);
jobInProgress = false;
statusText = "Job succeeded.";
}
});
// Execute analysis and wait for the results job.start();
}
// Extract the layer from the result and add to the mapfunctionprocessResults(result) {
mapView.map.operationalLayers.clear();
const layer = result.mapImageLayer;
layer.loadStatusChanged.connect(()=> {
if (layer.loadStatus === Enums.LoadStatusLoaded)
mapView.setViewpointGeometry(layer.fullExtent);
});
mapView.map.operationalLayers.append(layer);
}
functionshowErrorDialog(error) {
messageDialog.title = "Error";
messageDialog.text = "Executing geoprocessing failed.";
messageDialog.detailedText = error ? error.additionalMessage : "Unknown error";
messageDialog.open();
}
}
// Declare the GeoprocessingParameters and set the execution typeGeoprocessingParameters {
id: hotspotParametersexecutionType: Enums.GeoprocessingExecutionTypeAsynchronousSubmit
functionaddParameter(fromDateString, toDateString) {
// create the query stringlet queryString = "(\"DATE\" > date '%1 00:00:00' AND \"DATE\" < date '%2 00:00:00')" queryString = queryString.arg(fromDateString).arg(toDateString);
// Add query that contains the date range and the days of the week that are used in analysisconst inputs = {};
inputs["Query"] = ArcGISRuntimeEnvironment.createObject("GeoprocessingString", { value: queryString });
hotspotParameters.inputs = inputs;
// run the task hotspotTask.runTask();
}
}
// Create the settings rectangle to set dates and execute the taskRectangle {
anchors {
margins: -10fill: settingsColumn
}
color: "lightgrey"radius: 5border.color: "black"opacity: 0.75 }
Column {
id: settingsColumnanchors {
right: parent.right
top: parent.top
margins: 20 }
spacing: 5Text {
anchors.horizontalCenter: parent.horizontalCenter
text: "Select date range for analysis\n(d MMM yyyy)"font.pixelSize: 14 }
Text {
text: "From"font.pixelSize: 12 }
TextField {
id: fromDatewidth: parent.width
text: "1 Jan 1998"onTextChanged: {
fromThisDate = Date.fromLocaleString(Qt.locale(), text, "d MMM yyyy")
validateDates();
}
selectByMouse: true }
Text {
text: "To"font.pixelSize: 12 }
TextField {
id: toDatewidth: parent.width
text: "31 Jan 1998"onTextChanged: {
toThisDate = Date.fromLocaleString(Qt.locale(), text, "d MMM yyyy")
validateDates();
}
selectByMouse: true }
Button {
width: parent.width
anchors.horizontalCenter: parent.horizontalCenter
text: "Run analysis"enabled: !jobInProgress && validateDates(fromThisDate, toThisDate)
onClicked: {
const fromString = fromThisDate.toLocaleString(Qt.locale(), "yyyy-MM-dd");
const toString = toThisDate.toLocaleString(Qt.locale(), "yyyy-MM-dd");
// Run the task hotspotParameters.addParameter(fromString, toString);
}
}
Row {
spacing: 15visible: jobInProgress
BusyIndicator {
anchors.verticalCenter: parent.verticalCenter
width: 24height: width
}
Text {
anchors.verticalCenter: parent.verticalCenter
text: statusText
font.pixelSize: 14 }
}
}
Dialog {
id: messageDialogmodal: truex: Math.round(parent.width - width) / 2y: Math.round(parent.height - height) / 2standardButtons: Dialog.Ok
title: "Error"property alias text : textLabel.text
property alias detailedText : detailsLabel.text
ColumnLayout {
Text {
id: textLabel }
Text {
id: detailsLabel }
}
}
// function to validate the date ranges providedfunctionvalidateDates() {
// check that the to date is after the from dateif (fromThisDate > toThisDate) {
returnfalse;
}
// check that there is at least one day in between the from and to dateconst oneDay = 86400000;
if ((toThisDate - fromThisDate) < oneDay) {
returnfalse;
}
returntrue;
}
}