RInterface.GetArrayToVBA() 是否总是返回一个数组？

Question

参考来自 Wilmott 论坛的this 问题，我刚刚编写了以下函数：

Public Function KmeansPrice(ByVal priceArray As Range, _
                            ByVal clustersNumber As Integer) As Double

    ' Following rows are reproducible only if RExcel has been installed
    ' on your Excel!

    Dim y() As Double

    RInterface.StartRServer
    RInterface.PutArrayFromVBA "x", priceArray
    RInterface.PutArrayFromVBA "n", clustersNumber
    RInterface.RRun "x = as.numeric(x)"
    RInterface.RRun "cluster = kmeans(x, n)$cluster"
    RInterface.RRun "bestBid = rep(NA, n)"
    RInterface.RRun "for(i in 1:n)" & _
                    "{" & _
                    "  assign(paste('group.', i, sep = ''), " & _
                    "         x[cluster == i]);" & _
                    "  bestBid[i] = max(get(paste('group.', i, sep = '')))" & _
                    "}"
    RInterface.RRun "y = min(bestBid) + 0.01"
    y = RInterface.GetArrayToVBA("y")
    KmeansPrice = y(0, 0)

End Function

当然我之前在R做过原型，而且工作正常，那么我猜是这个错误的原因：

Error -2147220501
in Module RExcel.RServer

Error in variable assignment

与 RInterface.GetArrayToVBA() 的错误用法有关，涉及从 R 到 VBA 的数组的维度和索引。

是否有人能够使上面的代码工作？一个只有五个或十个元素的数组的工作示例priceArray 和clustersNumber 等于 2 或 3 就足够了。

Answer 1

我对聚类函数不熟悉，但这会返回结果而不会中断。

我更喜欢在 R 编辑器中创建我的函数，然后获取代码，所以我在 R 中进行了此操作，然后获取了我的 R 函数。

kmeansPrice <- function(priceArray,clustersNumber)
{
  `[` <- function(...) base::`[`(...,drop=FALSE) #in case we have a 1 dimensional table
  x<-priceArray
  n<- clustersNumber
  x<-matrix(as.numeric(x),nrow=dim(x)[1],ncol=dim(x)[2])
  cluster = kmeans(x, n)$cluster
  bestBid = rep(NA, n)
  for(i in 1:n)
  {
    assign(paste('group.', i, sep = ''),
    x[cluster == i])
    bestBid[i] = max(get(paste('group.', i, sep = '')))
  }
  return(min(bestBid) + 0.01)
}

那么你就可以了

Public Function KmeansPrice(ByVal priceArray As Range, _
                            ByVal clustersNumber As Integer) As Double

rinterface.PutArrayFromVBA "priceArray", priceArray.Value 'I think this ".Value" was your problem'
rinterface.PutArrayFromVBA "clustersNumber", clustersNumber
rinterface.RRun "theResult <- kmeansPrice(priceArray,clustersNumber)"
y = rinterface.GetRExpressionValueToVBA("theResult") 'preferred to GetArrayToVBA for single-value results'
KmeansPrice = y
End Function

并使用示例数据运行它：计算结果为的 2x4 表

     [,1] [,2]
[1,]    5    9
[2,]    6   10
[3,]    7   11
[4,]    8   12

有 3 个“集群”

Sub runkmeans()
theResult = KmeansPrice(Range("BH2:BI5"), 3)
MsgBox (theResult)
End Sub

产生 6.01