class1.cls

这个是利用地理信息系统组件MO做的武汉道路污染源强的分析系统。

VERSION 1.0 CLASS
BEGIN
  MultiUse = -1  'True
  Persistable = 0  'NotPersistable
  DataBindingBehavior = 0  'vbNone
  DataSourceBehavior  = 0  'vbNone
  MTSTransactionMode  = 0  'NotAnMTSObject
END
Attribute VB_Name = "Class1"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = True
Attribute VB_PredeclaredId = False
Attribute VB_Exposed = False
Public Function shortpath(startno As Integer, endno As Integer) As Single
'以开始点，结束点为参数。
Dim result() As Single
Dim result1 As Integer
'定义结果点
Dim s1 As Single
Dim min As Single
Dim ii, i, j, aa As Integer
Dim yc() As Boolean
Dim ycd() As Boolean
Dim rs1() As Single
Dim no() As Integer
Dim nopoint As Integer
ReDim yc(1 To maxno) As Boolean
ReDim ycd(1 To maxno) As Boolean
ReDim rs1(1 To maxno) As Single
ReDim result(1 To 2, 1 To maxno) As Single
'定义结果，其中result(1,maxno)为结果点，result(2,maxno)为结果长度。
For i = 1 To maxno
'// maxno为网中最大的节点数。
yc(i) = False
'//标记已经查过的点。
ycd(i) = False
'//标记已经作结果点用过的点
rs1(i) = 1E+38
'//假设从起点到任一点的距离都为无穷大
Next i
ll = startno
'//设置开始点。
yc(ll) = True
'//标记开始点为真。即已经作结果点用过。
j = 0
For aa = 1 To maxno
'先从与开始点相连的终点寻找
For i = 1 To indexa1(2, ll)
'//以与ll点相连的起点的个数循环
result1 = b1(indexa1(1, ll) - i + 1)
'找出与LL点相连的终点的点号
s1 = c1(indexa1(1, ll) - i + 1) + result(2, ll)
'找出长度并求和
If yc(result1) = True Then GoTo 200
'如果以被经查过进行下一个
If ycd(result1) = True Then
'//如果已经作为结果点判断哪一个长
If rs1(result1) >= s1 Then
'//如果这一点到起点的长度比现在的路线长，替代
rs1(result1) = s1
result(1, result1) = ll
'//设置到这点的最短路径的前一点为LL点（精华部分）
result(2, result1) = s1
'设置到这点的最短路径长度
GoTo 200
Else
GoTo 200
End If
End If
'如果上面的条件都不符合则进行下面的语句
ycd(result1) = True
rs1(result1) = s1
result(1, result1) = ll
result(2, result1) = s1
'每找到一个点加一，为了下面的判断
j = j + 1
ReDim Preserve no(1 To j) As Integer
'从新 定义数组并使其值为当前的点号
no(j) = result1
200 Next i
'再从与开始点相连的终点寻找，与上面一样不再标注
For i = 1 To indexb2(2, ll)
result1 = a2(indexb2(1, ll) - i + 1)
s1 = c2(indexb2(1, ll) - i + 1) + result(2, ll)
If yc(result1) = True Then GoTo 300
If ycd(result1) = True Then
If rs1(result1) >= s1 Then
rs1(result1) = s1
result(1, result1) = ll
result(2, result1) = s1
GoTo 300
Else
GoTo 300
End If
End If
ycd(result1) = True
rs1(result1) = s1
result(1, result1) = ll
result(2, result1) = s1
j = j + 1
ReDim Preserve no(1 To j) As Integer
no(j) = result1
300 Next i

'设置最小为无穷大，最短路径点为空
min = 1E+38
minpoint = Null
'（优化部分）
'找出已经查过点中长度最短的点
For i = aa To j
If min > rs1(no(i)) Then
ii = i
min = rs1(no(i))
minpoint = no(i)
End If
Next i
'如果没有结果，即起点与终点没有通路退出程序
If min = 1E+38 Then Exit Function
'（重点优化）将两点互换，减少循环。
no(ii) = no(aa)
no(aa) = minpoint
'标记已经作为结果点判断过
yc(minpoint) = True
ll = minpoint
'判断结果点是否等于终点，如果等于则已经找到最短路径
If minpoint = endno Then Exit For
Next aa
'返回最短路径长度
Stpath = result(2, endno)
End Function