IClusterer.Items Property
Returns the collection of cluster representatives.
Namespace: DevExpress.XtraMap
Assembly: DevExpress.XtraMap.v23.2.dll
NuGet Package: DevExpress.Win.Map
Declaration
Property Value
| Type | Description |
|---|---|
| MapItemCollection | A MapItemCollection object. |
Example
To implement a custom clusterer, design a class implementing the IClusterer interface and its IClusterer.Clusterize and IClusterer.SetOwner abstract methods, and IClusterer.Items and IClusterer.IsBusyproperties.
In this example, the CURE clustering method is implemented. Note that it has a high algorithmic complexity.
Note
- The owner adapter’s IMapDataAdapter.OnClustered method should be called to notify the Adapter that clustering is finished.
- When creating a cluster representative collection, send an owner as the constructor argument.
using DevExpress.XtraMap;
using System;
using System.Collections.Generic;
using System.Globalization;
using System.Windows.Forms;
using System.Xml.Linq;
namespace CustomClustererSample {
public partial class Form1 : Form {
VectorItemsLayer VectorLayer { get { return (VectorItemsLayer)map.Layers["VectorLayer"]; } }
ListSourceDataAdapter DataAdapter { get { return (ListSourceDataAdapter)VectorLayer.Data; } }
public Form1() {
InitializeComponent();
}
private void Form1_Load(object sender, EventArgs e) {
VectorLayer.DataLoaded += (obj, args) => { map.ZoomToFitLayerItems(); };
DataAdapter.DataSource = LoadData();
DataAdapter.Clusterer = new CureClusterer();
}
List<Tree> LoadData() {
List<Tree> trees = new List<Tree>();
XDocument doc = XDocument.Load("Data\\treesCl.xml");
foreach (XElement xTree in doc.Element("RowSet").Elements("Row"))
trees.Add(new Tree {
Latitude = Convert.ToDouble(xTree.Element("lat").Value, CultureInfo.InvariantCulture),
Longitude = Convert.ToDouble(xTree.Element("lon").Value, CultureInfo.InvariantCulture),
LocationName = xTree.Element("location").Value
});
return trees;
}
}
}
using DevExpress.Map;
using DevExpress.XtraMap;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading;
namespace CustomClustererSample {
class CureClusterer : IClusterer {
bool isBusy;
int clusterCount = 10;
MapItemCollection currentItems;
IMapDataAdapter owner;
public CureClusterer() {
isBusy = false;
}
public bool IsBusy {
get {
return isBusy;
}
}
public MapItemCollection Items {
get {
return currentItems;
}
}
public int ClusterCount {
get { return clusterCount; }
set {
if (value < 1) throw new ArgumentOutOfRangeException("The ClusterCount should be larger than 1.");
ClusterCount = value;
}
}
public void Clusterize(IEnumerable<MapItem> sourceItems, MapViewport viewport, bool sourceChanged) {
Thread clusteringThread = new Thread(() => {
isBusy = true;
if (sourceChanged) {
currentItems = ClusterizeImpl(sourceItems);
owner.OnClustered();
}
isBusy = false;
});
clusteringThread.Start();
}
public void SetOwner(IMapDataAdapter owner) {
this.owner = owner;
}
MapItemCollection ClusterizeImpl(IEnumerable<MapItem> sourceItems) {
// Separate localizable and non localizable items.
List<MapItem> nonLocalizableItems = new List<MapItem>();
List<Cluster> clusters = new List<Cluster>();
foreach (MapItem item in sourceItems) {
ISupportCoordLocation localizableItem = item as ISupportCoordLocation;
if (localizableItem != null)
clusters.Add(Cluster.Initialize(localizableItem));
else
nonLocalizableItems.Add(item);
}
// Arrange initial clusters in increasing order of distance to a closest cluster.
clusters = Arrange(clusters);
// Aggregate localizable items.
while (clusters.Count > ClusterCount) {
MergeCloserstClusters(ref clusters);
}
// Convert internal cluster helpers to Map items.
MapItemCollection clusterRepresentatives = new MapItemCollection(owner);
for (int i = 0; i < clusters.Count; ++i) {
Cluster cluster = clusters[i];
MapDot representative = new MapDot() { Location = new GeoPoint(cluster.CenterPoint.Y, cluster.CenterPoint.X), Size = 100 };
representative.ClusteredItems = cluster.Items.Select(item => item as MapItem).ToList();
representative.TitleOptions.Pattern = representative.ClusteredItems.Count.ToString();
clusterRepresentatives.Add(representative);
}
clusterRepresentatives.AddRange(nonLocalizableItems);
return clusterRepresentatives;
}
static List<Cluster> Arrange(List<Cluster> clusters) {
List<Cluster> arrangedClusters = new List<Cluster>();
for (int i = 0; i < clusters.Count; ++i) {
Cluster cluster = clusters[i];
AssignClosest(cluster, clusters);
// Inserts depending on distance to closest.
Insert(arrangedClusters, cluster);
}
return arrangedClusters;
}
static void AssignClosest(Cluster cluster, List<Cluster> clusters) {
if (clusters.Count < 2) throw new ArgumentOutOfRangeException("Clusters count should be larger than 2.");
Cluster distancableCluster = clusters[0];
if (distancableCluster == cluster)
distancableCluster = clusters[1];
cluster.ClosestCluster = distancableCluster;
for (int i = 0; i < clusters.Count; ++i) {
distancableCluster = clusters[i];
if (distancableCluster == cluster) continue;
double distance = cluster.DistanceTo(distancableCluster);
if (distance < cluster.DistanceToClosest)
cluster.ClosestCluster = distancableCluster;
}
}
static void Insert(List<Cluster> clusters, Cluster cluster) {
for (int i = 0; i < clusters.Count; ++i) {
if (clusters[i].DistanceToClosest > cluster.DistanceToClosest) {
clusters.Insert(i, cluster);
return;
}
}
clusters.Add(cluster);
}
static void MergeCloserstClusters(ref List<Cluster> clusters) {
if (clusters.Count < 2) throw new ArgumentOutOfRangeException("Clusters count should be larger than 2.");
Cluster cluster1 = clusters[0];
Cluster cluster2 = cluster1.ClosestCluster;
clusters.RemoveAt(0);
clusters.Remove(cluster2);
Cluster newCluster = Cluster.Merge(cluster1, cluster2);
clusters.Add(newCluster);
clusters = Arrange(clusters);
}
}
class Cluster {
MapPoint centerPoint;
List<ISupportCoordLocation> items;
Cluster closestCluster;
double distanceToClosest;
public Cluster(List<ISupportCoordLocation> items) {
this.items = items;
centerPoint = CalculateCenterPoint(items);
}
public static Cluster Initialize(ISupportCoordLocation item) {
List<ISupportCoordLocation> items = new List<ISupportCoordLocation>();
items.Add(item);
return new Cluster(items);
}
public MapPoint CenterPoint { get { return this.centerPoint; } }
public List<ISupportCoordLocation> Items { get { return this.items; } }
public Cluster ClosestCluster {
get { return this.closestCluster; }
set {
this.closestCluster = value;
distanceToClosest = DistanceTo(closestCluster);
}
}
public double DistanceToClosest { get { return distanceToClosest; } }
public double DistanceTo(Cluster h) {
return Math.Sqrt((h.CenterPoint.X - CenterPoint.X) * (h.CenterPoint.X - CenterPoint.X) +
(h.CenterPoint.Y - CenterPoint.Y) * (h.CenterPoint.Y - CenterPoint.Y));
}
public static Cluster Merge(Cluster cluster1, Cluster cluster2) {
List<ISupportCoordLocation> newItems = new List<ISupportCoordLocation>(cluster1.Items);
newItems.AddRange(cluster2.Items);
return new Cluster(newItems);
}
public static MapPoint CalculateCenterPoint(List<ISupportCoordLocation> items) {
double meanX = 0;
double meanY = 0;
foreach (ISupportCoordLocation item in items) {
meanX += item.Location.GetX();
meanY += item.Location.GetY();
}
meanX /= items.Count;
meanY /= items.Count;
return new MapPoint(meanX, meanY);
}
}
}
using System;
namespace CustomClustererSample {
class Tree {
string locationName;
public Tree() {
locationName = "";
}
public double Latitude { get; set; }
public double Longitude { get; set; }
public string LocationName {
get { return this.locationName; }
set {
if (value == null) throw new ArgumentNullException("LocationName");
if (value.Equals(this.locationName)) return;
this.locationName = value;
}
}
}
}
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using System.Windows.Forms;
namespace CustomClustererSample {
static class Program {
/// <summary>
/// The main entry point for the application.
/// </summary>
[STAThread]
static void Main() {
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
Application.Run(new Form1());
}
}
}
Imports System
Namespace CustomClustererSample
Friend Class Tree
Private locationName_Renamed As String
Public Sub New()
locationName_Renamed = ""
End Sub
Public Property Latitude() As Double
Public Property Longitude() As Double
Public Property LocationName() As String
Get
Return Me.locationName_Renamed
End Get
Set(ByVal value As String)
If value Is Nothing Then
Throw New ArgumentNullException("LocationName")
End If
If value.Equals(Me.locationName_Renamed) Then
Return
End If
Me.locationName_Renamed = value
End Set
End Property
End Class
End Namespace
Imports DevExpress.XtraMap
Imports System
Imports System.Collections.Generic
Imports System.Globalization
Imports System.Windows.Forms
Imports System.Xml.Linq
Namespace CustomClustererSample
Partial Public Class Form1
Inherits Form
Private ReadOnly Property VectorLayer() As VectorItemsLayer
Get
Return CType(map.Layers("VectorLayer"), VectorItemsLayer)
End Get
End Property
Private ReadOnly Property DataAdapter() As ListSourceDataAdapter
Get
Return CType(VectorLayer.Data, ListSourceDataAdapter)
End Get
End Property
Public Sub New()
InitializeComponent()
End Sub
Private Sub Form1_Load(ByVal sender As Object, ByVal e As EventArgs) Handles Me.Load
AddHandler VectorLayer.DataLoaded, Sub(obj, args)
map.ZoomToFitLayerItems()
End Sub
DataAdapter.DataSource = LoadData()
DataAdapter.Clusterer = New CureClusterer()
End Sub
Private Function LoadData() As List(Of Tree)
Dim trees As New List(Of Tree)()
Dim doc As XDocument = XDocument.Load("Data\treesCl.xml")
For Each xTree As XElement In doc.Element("RowSet").Elements("Row")
trees.Add(New Tree With { _
.Latitude = Convert.ToDouble(xTree.Element("lat").Value, CultureInfo.InvariantCulture), _
.Longitude = Convert.ToDouble(xTree.Element("lon").Value, CultureInfo.InvariantCulture), _
.LocationName = xTree.Element("location").Value _
})
Next xTree
Return trees
End Function
End Class
End Namespace
Imports DevExpress.Map
Imports DevExpress.XtraMap
Imports System
Imports System.Collections.Generic
Imports System.Linq
Imports System.Threading
Namespace CustomClustererSample
Friend Class CureClusterer
Implements IClusterer
Private isBusy_Renamed As Boolean
Private clusterCount_Renamed As Integer = 10
Private currentItems As MapItemCollection
Private owner As IMapDataAdapter
Public Sub New()
isBusy_Renamed = False
End Sub
Public ReadOnly Property IsBusy() As Boolean Implements IClusterer.IsBusy
Get
Return isBusy_Renamed
End Get
End Property
Public ReadOnly Property Items() As MapItemCollection Implements IClusterer.Items
Get
Return currentItems
End Get
End Property
Public Property ClusterCount() As Integer
Get
Return clusterCount_Renamed
End Get
Set(ByVal value As Integer)
If value < 1 Then
Throw New ArgumentOutOfRangeException("The ClusterCount should be larger than 1.")
End If
clusterCount_Renamed = value
End Set
End Property
Public Sub Clusterize(ByVal sourceItems As IEnumerable(Of MapItem), ByVal viewport As MapViewport, ByVal sourceChanged As Boolean) Implements IClusterer.Clusterize
Dim clusteringThread As Thread = New Thread(Sub()
isBusy_Renamed = True
If sourceChanged Then
currentItems = ClusterizeImpl(sourceItems)
owner.OnClustered()
End If
isBusy_Renamed = False
End Sub)
clusteringThread.Start()
End Sub
Public Sub SetOwner(ByVal owner As IMapDataAdapter) Implements IClusterer.SetOwner
Me.owner = owner
End Sub
Private Function ClusterizeImpl(ByVal sourceItems As IEnumerable(Of MapItem)) As MapItemCollection
' Separate localizable and non localizable items.
Dim nonLocalizableItems As New List(Of MapItem)()
Dim clusters As New List(Of Cluster)()
For Each item As MapItem In sourceItems
Dim localizableItem As ISupportCoordLocation = TryCast(item, ISupportCoordLocation)
If localizableItem IsNot Nothing Then
clusters.Add(Cluster.Initialize(localizableItem))
Else
nonLocalizableItems.Add(item)
End If
Next item
' Arrange initial clusters in increasing order of distance to a closest cluster.
clusters = Arrange(clusters)
' Aggregate localizable items.
Do While clusters.Count > ClusterCount
MergeCloserstClusters(clusters)
Loop
' Convert internal cluster helpers to Map items.
Dim clusterRepresentatives As New MapItemCollection(owner)
For i As Integer = 0 To clusters.Count - 1
Dim cluster_Renamed As Cluster = clusters(i)
Dim representative As New MapDot() With { _
.Location = New GeoPoint(cluster_Renamed.CenterPoint.Y, cluster_Renamed.CenterPoint.X), _
.Size = 100 _
}
representative.ClusteredItems = cluster_Renamed.Items.Select(Function(item) TryCast(item, MapItem)).ToList()
representative.TitleOptions.Pattern = representative.ClusteredItems.Count.ToString()
clusterRepresentatives.Add(representative)
Next i
clusterRepresentatives.AddRange(nonLocalizableItems)
Return clusterRepresentatives
End Function
Private Shared Function Arrange(ByVal clusters As List(Of Cluster)) As List(Of Cluster)
Dim arrangedClusters As New List(Of Cluster)()
Dim i As Integer = 0
Do While i < clusters.Count
Dim cluster_Renamed As Cluster = clusters(i)
AssignClosest(cluster_Renamed, clusters)
' Inserts depending on distance to closest.
Insert(arrangedClusters, cluster_Renamed)
i += 1
Loop
Return arrangedClusters
End Function
Private Shared Sub AssignClosest(ByVal cluster_Renamed As Cluster, ByVal clusters As List(Of Cluster))
If clusters.Count < 2 Then
Throw New ArgumentOutOfRangeException("Clusters count should be larger than 2.")
End If
Dim distancableCluster As Cluster = clusters(0)
If distancableCluster Is cluster_Renamed Then
distancableCluster = clusters(1)
End If
cluster_Renamed.ClosestCluster = distancableCluster
For i As Integer = 0 To clusters.Count - 1
distancableCluster = clusters(i)
If distancableCluster Is cluster_Renamed Then
Continue For
End If
Dim distance As Double = cluster_Renamed.DistanceTo(distancableCluster)
If distance < cluster_Renamed.DistanceToClosest Then
cluster_Renamed.ClosestCluster = distancableCluster
End If
Next i
End Sub
Private Shared Sub Insert(ByVal clusters As List(Of Cluster), ByVal cluster_Renamed As Cluster)
Dim i As Integer = 0
Do While i < clusters.Count
If clusters(i).DistanceToClosest > cluster_Renamed.DistanceToClosest Then
clusters.Insert(i, cluster_Renamed)
Return
End If
i += 1
Loop
clusters.Add(cluster_Renamed)
End Sub
Private Shared Sub MergeCloserstClusters(ByRef clusters As List(Of Cluster))
If clusters.Count < 2 Then
Throw New ArgumentOutOfRangeException("Clusters count should be larger than 2.")
End If
Dim cluster1 As Cluster = clusters(0)
Dim cluster2 As Cluster = cluster1.ClosestCluster
clusters.RemoveAt(0)
clusters.Remove(cluster2)
Dim newCluster As Cluster = Cluster.Merge(cluster1, cluster2)
clusters.Add(newCluster)
clusters = Arrange(clusters)
End Sub
End Class
Friend Class Cluster
Private centerPoint_Renamed As MapPoint
Private items_Renamed As List(Of ISupportCoordLocation)
Private closestCluster_Renamed As Cluster
Private distanceToClosest_Renamed As Double
Public Sub New(ByVal items As List(Of ISupportCoordLocation))
Me.items_Renamed = items
centerPoint_Renamed = CalculateCenterPoint(items)
End Sub
Public Shared Function Initialize(ByVal item As ISupportCoordLocation) As Cluster
Dim items_Renamed As New List(Of ISupportCoordLocation)()
items_Renamed.Add(item)
Return New Cluster(items_Renamed)
End Function
Public ReadOnly Property CenterPoint() As MapPoint
Get
Return Me.centerPoint_Renamed
End Get
End Property
Public ReadOnly Property Items() As List(Of ISupportCoordLocation)
Get
Return Me.items_Renamed
End Get
End Property
Public Property ClosestCluster() As Cluster
Get
Return Me.closestCluster_Renamed
End Get
Set(ByVal value As Cluster)
Me.closestCluster_Renamed = value
distanceToClosest_Renamed = DistanceTo(closestCluster_Renamed)
End Set
End Property
Public ReadOnly Property DistanceToClosest() As Double
Get
Return distanceToClosest_Renamed
End Get
End Property
Public Function DistanceTo(ByVal h As Cluster) As Double
Return Math.Sqrt((h.CenterPoint.X - CenterPoint.X) * (h.CenterPoint.X - CenterPoint.X) + (h.CenterPoint.Y - CenterPoint.Y) * (h.CenterPoint.Y - CenterPoint.Y))
End Function
Public Shared Function Merge(ByVal cluster1 As Cluster, ByVal cluster2 As Cluster) As Cluster
Dim newItems As New List(Of ISupportCoordLocation)(cluster1.Items)
newItems.AddRange(cluster2.Items)
Return New Cluster(newItems)
End Function
Public Shared Function CalculateCenterPoint(ByVal items As List(Of ISupportCoordLocation)) As MapPoint
Dim meanX As Double = 0
Dim meanY As Double = 0
For Each item As ISupportCoordLocation In items
meanX += item.Location.GetX()
meanY += item.Location.GetY()
Next item
meanX /= items.Count
meanY /= items.Count
Return New MapPoint(meanX, meanY)
End Function
End Class
End Namespace
Imports System
Imports System.Collections.Generic
Imports System.Linq
Imports System.Threading.Tasks
Imports System.Windows.Forms
Namespace CustomClustererSample
Friend NotInheritable Class Program
Private Sub New()
End Sub
''' <summary>
''' The main entry point for the application.
''' </summary>
<STAThread> _
Shared Sub Main()
Application.EnableVisualStyles()
Application.SetCompatibleTextRenderingDefault(False)
Application.Run(New Form1())
End Sub
End Class
End Namespace
See Also