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For p1 = 1 to numPoints
For p2 = p1 + 1 to numPoints
...calculate {distance}
...if {distance} < minDistance then minDist = {distance}
Next p2
Next p1
, x * ( n - 1 ) / 2.
, 5 10 :
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- 1 ↔ 3
- 1 ↔ 4
- 1 ↔ 5
- 2 ↔ 3
- 2 ↔ 4
- 2 ↔ 5
- 3 ↔ 4
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Sub findShortestDist_Excel()
Const colLatitude = "C" ' Col.C = Lat, Col.D = Lon
Dim pointList As Range, pointCount As Long, c As Range, _
arrCoords(), x As Long, y As Long
Dim thisDist As Double, minDist As Double, minDist_txt As String
Dim cntCurr As Long, cntTotal As Long, timerStart As Single
timerStart = Timer
Set pointList = Sheets("Stops").UsedRange.Columns(colLatitude)
pointCount = WorksheetFunction.Count(pointList.Columns(1))
'build array of numbers found in Column C/D
ReDim arrCoords(1 To 3, 1 To pointCount)
For Each c In pointList.Columns(1).Cells
If IsNumeric(c.Value) And Not IsEmpty(c.Value) Then
x = x + 1
arrCoords(1, x) = c.Value
arrCoords(2, x) = c.Offset(0, 1).Value
End If
Next c
minDist = -1
cntTotal = pointCount * (pointCount + 1) / 2
'loop through array
For x = 1 To pointCount
For y = x + 1 To pointCount
If (arrCoords(1, x) & arrCoords(2, x)) <> (arrCoords(1, y) & arrCoords(2, y)) Then
cntCurr = cntCurr + 1
thisDist = Distance(arrCoords(1, x), arrCoords(2, x), _
arrCoords(1, y), arrCoords(2, y))
'check if this distance is the smallest yet
If ((thisDist < minDist) Or (minDist = -1)) And thisDist > 0 Then
minDist = thisDist
'minDist_txt = arrCoords(1, x) & "," & arrCoords(2, x) & " -> " & arrCoords(1, y) & "," & arrCoords(2, y)
End If
'Application.StatusBar = "Calculating Distances: " & Format(cntCurr / cntTotal, "0.0%")
End If
Next y
'DoEvents
Next x
Debug.Print "Minimum distance: " & minDist_txt & " = " & minDist & " meters"
Debug.Print "(" & Round(Timer - timerStart, 2) & "sec)"
Application.StatusBar = "Finished. Minimum distance: " & minDist_txt & " = " & minDist & "m"
End Sub
, ( Access Excel):
Excel:
Public Function Distance(ByVal lat1 As Double, ByVal lon1 As Double, _
ByVal lat2 As Double, ByVal lon2 As Double) As Double
'returns Meters distance in Excel (straight-line)
Dim theta As Double: theta = lon1 - lon2
Dim Dist As Double: Dist = Math.Sin(deg2rad(lat1)) * Math.Sin(deg2rad(lat2)) + Math.Cos(deg2rad(lat1)) * Math.Cos(deg2rad(lat2)) * Math.Cos(deg2rad(theta))
Dist = rad2deg(WorksheetFunction.Acos(Dist))
Distance = Dist * 60 * 1.1515 * 1.609344 * 1000
End Function
Function deg2rad(ByVal deg As Double) As Double
deg2rad = (deg * WorksheetFunction.PI / 180#)
End Function
Function rad2deg(ByVal rad As Double) As Double
rad2deg = rad / WorksheetFunction.PI * 180#
End Function
... Microsoft Access:
:
Sub findShortestDist_Access()
Const tableName = "Stops"
Dim pointCount As Long, arrCoords(), x As Long, y As Long
Dim thisDist As Double, minDist As Double
Dim cntCurr As Long, cntTotal As Long, timerStart As Single
Dim rs As Recordset
timerStart = Timer
Set rs = CurrentDb.OpenRecordset("SELECT * FROM " & tableName)
With rs
.MoveLast
.MoveFirst
pointCount = .RecordCount
'build array of numbers found in Column C/D
ReDim arrCoords(1 To 2, 1 To pointCount)
Do While Not .EOF
x = x + 1
arrCoords(1, x) = !stop_lat
arrCoords(2, x) = !stop_lon
.MoveNext
Loop
.Close
End With
minDist = -1
cntTotal = pointCount * (pointCount + 1) / 2
SysCmd acSysCmdInitMeter, "Calculating Distances:", cntTotal
'loop through array
For x = 1 To pointCount
For y = x + 1 To pointCount
cntCurr = cntCurr + 1
thisDist = Distance(arrCoords(1, x), arrCoords(2, x), _
arrCoords(1, y), arrCoords(2, y))
'check if this distance is the smallest yet
If ((thisDist < minDist) Or (minDist = -1)) And thisDist > 0 Then
minDist = thisDist
End If
SysCmd acSysCmdUpdateMeter, cntCurr
Next y
DoEvents
Next x
SysCmd acSysCmdRemoveMeter
Debug.Print "Minimum distance: " & minDist_txt & " = " & minDist & " meters"
Debug.Print "(" & Round(Timer - timerStart, 2) & "sec)"
End Sub
, ... (Access , , Excel)
:
Const pi As Double = 3.14159265358979
Public Function Distance(ByVal lat1 As Double, ByVal lon1 As Double, _
ByVal lat2 As Double, ByVal lon2 As Double) As Double
'returns Meters distance in Access (straight-line)
Dim theta As Double: theta = lon1 - lon2
Dim dist As Double
dist = Math.Sin(deg2rad(lat1)) * Math.Sin(deg2rad(lat2)) + Math.Cos(deg2rad(lat1)) _
* Math.Cos(deg2rad(lat2)) * Math.Cos(deg2rad(theta))
dist = rad2deg(aCos(dist))
Distance = dist * 60 * 1.1515 * 1.609344 * 1000
End Function
Function deg2rad(ByVal deg As Double) As Double
deg2rad = (deg * pi / 180#)
End Function
Function rad2deg(ByVal rad As Double) As Double
rad2deg = rad / pi * 180#
End Function
Function aTan2(x As Double, y As Double) As Double
aTan2 = Atn(y / x)
End Function
Function aCos(x As Double) As Double
On Error GoTo aErr
If x = 0 Or Abs(x) = 1 Then
aCos = 0
Else
aCos = Atn(-x / Sqr(-x * x + 1)) + 2 * Atn(1)
End If
Exit Function
aErr:
aCos = 0
End Function
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