ArcGIS 9.3+VB.NET实现空间泊松分布随机点生成算法

            Dim totalArea As Double = 579.2 '
            lao = N / totalArea

            wedit.StartEditing(True)
            wedit.StartEditOperation()
            '删除所有病例 除了两个空病例 空病例的目的是为了 保持xydomain不变化
            Dim ptable As ITable = fccsr
            Dim filter1 As IQueryFilter = New QueryFilter
            filter1.WhereClause = "not run is null"
            ptable.DeleteSearchedRows(filter1)

            Dim tmpCursor As IFeatureCursor = fccsr.Insert(True) '往caseadd里增加新的病例
            Dim fb As IFeatureBuffer = fccsr.CreateFeatureBuffer
            Dim iRun As Integer = fccsr.Fields.FindField("run"), iiN As Integer = fccsr.Fields.FindField("N") '

            Dim count As Integer = 0
            While r < 20000
                Dim x As Double = -Log(Rnd()) / lao '生成指数分布的随机数  平方米
                If count = 0 Then
                    dr = Sqrt(x * 1000000.0 / PI)  '转换成以米为单位
                Else
                    dr = x * 1000000.0 / 2 / PI / r
                End If
                r += dr
                th = Rnd() * 2 * PI
                Dim pt As IPoint = New Point
                pt.PutCoords(r * Cos(th), r * Sin(th))
                fb.Value(iRun) = 0 '病种
                fb.Value(iiN) = N