Analyze hotspots

View inJavaKotlin
View on GitHub
Sample viewer app

Use a geoprocessing service and a set of features to identify statistically significant hot spots and cold spots.

Image of analyze hotspots

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

  1. Create a GeoprocessingTask with the URL set to the endpoint of a geoprocessing service.
  2. Create a query string with the date range as an input of GeoprocessingParameters.
  3. Use the GeoprocessingTask to create a GeoprocessingJob with the GeoprocessingParameters instance.
  4. Start the GeoprocessingJob and wait for it to complete and return a GeoprocessingResult.
  5. Get the resulting ArcGISMapImageLayer using GeoprocessingResult.mapImageLayer.
  6. Add the layer to the map's operational layers.

Relevant API

  • GeoprocessingJob
  • GeoprocessingParameters
  • GeoprocessingResult
  • GeoprocessingTask

Tags

analysis, density, geoprocessing, hot spots, hotspots

Sample Code

MainActivity.kt
Use dark colors for code blocks
                                                                                                                                                                                                                                                                             
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
/*
 * 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.
 *
 */

package com.esri.arcgisruntime.sample.analyzehotspots

import android.app.DatePickerDialog
import android.app.Dialog
import android.app.ProgressDialog
import android.os.Bundle
import android.util.Log
import android.widget.Toast
import androidx.appcompat.app.AppCompatActivity
import com.esri.arcgisruntime.ArcGISRuntimeEnvironment
import com.esri.arcgisruntime.concurrent.Job
import com.esri.arcgisruntime.geometry.Point
import com.esri.arcgisruntime.geometry.SpatialReference
import com.esri.arcgisruntime.mapping.ArcGISMap
import com.esri.arcgisruntime.mapping.BasemapStyle
import com.esri.arcgisruntime.mapping.Viewpoint
import com.esri.arcgisruntime.mapping.view.MapView
import com.esri.arcgisruntime.sample.analyzehotspots.databinding.ActivityMainBinding
import com.esri.arcgisruntime.sample.analyzehotspots.databinding.DateRangeDialogBinding
import com.esri.arcgisruntime.tasks.geoprocessing.GeoprocessingString
import com.esri.arcgisruntime.tasks.geoprocessing.GeoprocessingTask
import com.google.android.material.floatingactionbutton.FloatingActionButton
import java.text.SimpleDateFormat
import java.util.*

// enum to flag whether the date picker calendar shown should be for the 'from' or 'to' date
enum class InputCalendar {
  From, To
}

class MainActivity : AppCompatActivity() {

  private val activityMainBinding by lazy {
    ActivityMainBinding.inflate(layoutInflater)
  }

  private val mapView: MapView by lazy {
    activityMainBinding.mapView
  }

  private val calendarButton: FloatingActionButton by lazy {
    activityMainBinding.calendarButton
  }

  private val TAG = this::class.java.simpleName

  override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(activityMainBinding.root)

    // authentication with an API key or named user is required to access basemaps and other
    // location services
    ArcGISRuntimeEnvironment.setApiKey(BuildConfig.API_KEY)

    // create a map with the BasemapType topographic
    val map = ArcGISMap(BasemapStyle.ARCGIS_TOPOGRAPHIC)

    // set the map to the map view
    mapView.map = map
    mapView.setViewpoint(
      Viewpoint(
        Point(-13671170.0, 5693633.0, SpatialReference.create(3857)),
        57779.0
      )
    )

    calendarButton.setOnClickListener {
      showDateRangeDialog()
    }

    showDateRangeDialog()
  }

  /**
   * Creates the date range dialog. Includes listeners to handle click events,
   * which call showCalendar(...) or analyzeHotspots(...).
   */
  private fun showDateRangeDialog() {
    val geoprocessingTask = GeoprocessingTask(getString(R.string.hotspot_911_calls))

    val dateRangeDialogBinding = DateRangeDialogBinding.inflate(layoutInflater)
    // create custom dialog
    Dialog(this).apply {
      setContentView(dateRangeDialogBinding.root)
      setCancelable(true)

      dateRangeDialogBinding.fromDateText.setOnClickListener {
        showCalendar(dateRangeDialogBinding, InputCalendar.From)
      }

      dateRangeDialogBinding.toDateText.setOnClickListener {
        showCalendar(dateRangeDialogBinding, InputCalendar.To)
      }

      dateRangeDialogBinding.analyzeButton.setOnClickListener {
        analyzeHotspots(
          geoprocessingTask,
          dateRangeDialogBinding.fromDateText.text.toString(),
          dateRangeDialogBinding.toDateText.text.toString()
        )
        dismiss()
      }
    }.show()
  }

  /**
   * Shows a date picker dialog and writes the date chosen to the correct editable text.
   *
   * @param inputCalendar enum which specifies which editable text the chosen date should be written to
   */
  private fun showCalendar(
    dateRangeDialogBinding: DateRangeDialogBinding,
    inputCalendar: InputCalendar
  ) {

    // define the date picker dialog
    val calendar = Calendar.getInstance()
    val year = calendar.get(Calendar.YEAR)
    val month = calendar.get(Calendar.MONTH)
    val day = calendar.get(Calendar.DAY_OF_MONTH)

    DatePickerDialog(this, { _, year, monthOfYear, dayOfMonth ->

      val dateString = StringBuilder()
        .append(year)
        .append("-")
        .append(monthOfYear + 1)
        .append("-")
        .append(dayOfMonth)

      when (inputCalendar) {
        InputCalendar.From -> {
          dateRangeDialogBinding.fromDateText.setText(dateString)
        }
        InputCalendar.To -> {
          dateRangeDialogBinding.toDateText.setText(dateString)
        }
      }
    }, year, month, day).apply {
      datePicker.minDate = parseDate(getString(R.string.min_date))!!.time
      datePicker.maxDate = parseDate(getString(R.string.max_date))!!.time
      if (inputCalendar == InputCalendar.From) {
        updateDate(1998, 0, 1)
      }
    }.show()
  }

  /**
   * Runs the geoprocessing job, updating progress while loading. On job done, loads the resulting
   * ArcGISMapImageLayer to the map and resets the Viewpoint of the MapView.
   *
   * @param geoprocessingTask Geoprocessing task to generate hotspots
   * @param from string which holds a date
   * @param to   string which holds a date
   */
  private fun analyzeHotspots(geoprocessingTask: GeoprocessingTask, from: String, to: String) {
    geoprocessingTask.loadAsync()

    // a map image layer is generated as a result, clear previous results
    mapView.map.operationalLayers.clear()

    // create parameters for geoprocessing job
    val paramsFuture = geoprocessingTask.createDefaultParametersAsync()
    paramsFuture.addDoneListener {
      try {
        val geoprocessingParameters = paramsFuture.get()
        geoprocessingParameters.processSpatialReference = mapView.spatialReference
        geoprocessingParameters.outputSpatialReference = mapView.spatialReference

        val queryString = StringBuilder("(\"DATE\" > date '")
          .append(from)
          .append(" 00:00:00' AND \"DATE\" < date '")
          .append(to)
          .append(" 00:00:00')")

        val geoprocessingString = GeoprocessingString(queryString.toString())
        geoprocessingParameters.inputs["Query"] = geoprocessingString
        // create and start geoprocessing job
        val geoprocessingJob = geoprocessingTask.createJob(geoprocessingParameters)
        geoprocessingJob.start()

        // show progress
        val progressDialog = ProgressDialog(this).apply {
          setTitle(getString(R.string.app_name))
          setMessage(getString(R.string.dialog_text))
          setProgressStyle(ProgressDialog.STYLE_HORIZONTAL)
          show()
        }

        // update progress
        geoprocessingJob.addProgressChangedListener {
          val progress = geoprocessingJob.progress
          progressDialog.progress = progress
        }

        // when the job finishes
        geoprocessingJob.addJobDoneListener {
          // dismiss the dialog
          progressDialog.dismiss()

          when (geoprocessingJob.status) {
            Job.Status.SUCCEEDED -> {
              // get results
              val geoprocessingResult = geoprocessingJob.result
              val hotspotMapImageLayer = geoprocessingResult.mapImageLayer
              hotspotMapImageLayer.opacity = 0.5f

              // add new layer to map
              mapView.map.operationalLayers.add(hotspotMapImageLayer)

              // zoom to the layer extent
              hotspotMapImageLayer.addDoneLoadingListener {
                mapView.setViewpointGeometryAsync(hotspotMapImageLayer.fullExtent)
              }
            }
            else -> Toast.makeText(
              this,
              getString(R.string.job_failed),
              Toast.LENGTH_LONG
            ).show()
          }
        }
      } catch (e: Exception) {
        val error = "Error generating geoprocessing parameters: " + e.message
        Toast.makeText(this, error, Toast.LENGTH_LONG).show()
        Log.e(TAG, error)
      }
    }
  }

  /**
   * Parse the date using a simple date format.
   */
  private fun parseDate(date: String): Date? {
    return SimpleDateFormat(getString(R.string.date_format), Locale.US).parse(date)
  }

  override fun onPause() {
    mapView.pause()
    super.onPause()
  }

  override fun onResume() {
    super.onResume()
    mapView.resume()
  }

  override fun onDestroy() {
    mapView.dispose()
    super.onDestroy()
  }
}

Your browser is no longer supported. Please upgrade your browser for the best experience. See our browser deprecation post for more details.