为什么我生成随机数的种子不起作用？

Question

我需要生成几组随机数，我的代码的最小工作示例如下：

Sub Macro1()

Application.Calculation = xlCalculationManual
Application.ScreenUpdating = False

Dim RA1 As Variant
Dim RA2 As Variant
Dim RA3 As Variant
Dim RA4 As Variant
ReDim RA1(1 To 63)
ReDim RA2(1 To 63)
ReDim RA3(1 To 63)
ReDim RA4(1 To 63)

For i = 1 To 1000

    Rnd (-1)
    Randomize i

    For j = 1 To 63
            
        RA1(j) = Rnd
                             
    Next j
    
    Rnd (-2)
    Randomize i

    For k = 1 To 63
            
        RA2(k) = Rnd
                             
    Next k
    
    Rnd (-3)
    Randomize i

    For l = 1 To 63
            
        RA3(l) = Rnd
                             
    Next l
    
    Rnd (-4)
    Randomize i

    For m = 1 To 63
            
        RA4(m) = Rnd
                             
    Next m

    With Sheets("Economic Assumptions")
    
        .Range("B10:BL10").Value = RA1
        .Range("B11:BL11").Value = RA2
        .Range("B12:BL12").Value = RA3
        .Range("B13:BL13").Value = RA4
        .Calculate
        
    End With

Next i

End Sub

然而，虽然 RA1 是唯一的，但我发现我在 RA2、RA3 和 RA4 中的随机数在每个 i 中都完全相同。换句话说，我的代码给了我 RA1 <> RA2 = RA3 = RA4。这是为什么？我认为改变 RND 中的参数会改变随机数的种子？特别是，我需要 RA1、RA2、RA3 和 RA4 每个 i 都有自己的一组随机数，但是当我重新运行整个事情时，我应该每次都得到相同的随机数。我怎样才能调整我的代码来实现这个目标？

编辑

经过一些头脑风暴和猜测和检查工作后，以下代码可以解决问题！[=14=]

子宏 1()

Application.Calculation = xlCalculationManual
Application.ScreenUpdating = False

Dim RA1 As Variant
Dim RA2 As Variant
Dim RA3 As Variant
Dim RA4 As Variant
ReDim RA1(1 To 63)
ReDim RA2(1 To 63)
ReDim RA3(1 To 63)
ReDim RA4(1 To 63)

For i = 1 To 1000

    Rnd (-1)
    Randomize i

    For j = 1 To 63
            
        RA1(j) = Rnd
                             
    Next j

    For k = 1 To 63
            
        RA2(k) = Rnd
                             
    Next k

    For l = 1 To 63
            
        RA3(l) = Rnd
                             
    Next l

    For m = 1 To 63
            
        RA4(m) = Rnd
                             
    Next m
    
    With Sheets("Economic Assumptions")
    
        .Range("B10:BL10").Value = RA1
        .Range("B11:BL11").Value = RA2
        .Range("B12:BL12").Value = RA3
        .Range("B13:BL13").Value = RA4
        .Calculate
        
    End With

Next i

End Sub

它更短也更甜美。我很高兴:)

Answer 1

您可以分配给一个数组，将数组打乱 x 次，保存到其他数组，哑到 sheet。通过限制与 sheet 交互的次数，这也应该更快：

Option Explicit
Sub xx()
    Dim arr, nrOfsets As Long
    arr = WorksheetFunction.RandArray(1, 63)
    nrOfsets = 4
    
    Dim arr2, j As Long, i As Long
    ReDim arr2(1 To nrOfsets, 1 To UBound(arr))
    For j = 1 To nrOfsets
        For i = 1 To UBound(arr)
            arr2(j, i) = arr(i)
        Next i
        arr = Resample(arr):
    Next j
    
    Dim startrow As Long, startcol As Long
    startrow = 10: startcol = 2
    With Sheet3
        .Range(.Cells(startrow, startcol), .Cells(startrow - 1 + nrOfsets, startcol - 1 + UBound(arr2, 2))) = arr2
    End With
End Sub
   
Function Resample(data_vector As Variant) As Variant()
'source: 
   Dim shuffled_vector() As Variant
   shuffled_vector = data_vector
   Dim i As Long
   For i = UBound(shuffled_vector) To LBound(shuffled_vector) Step -1
       Dim t As Variant
       t = shuffled_vector(i)
       Dim j As Long
       j = Application.RandBetween(LBound(shuffled_vector), UBound(shuffled_vector))
       shuffled_vector(i) = shuffled_vector(j)
       shuffled_vector(j) = t
   Next i
   Resample = shuffled_vector
End Function

为什么我生成随机数的种子不起作用？

Why are my seeds for generating random numbers not working?

excel

vba

random

random-seed