在R中填充矢量

Question

我是R的初学者，当我诉诸for循环时，我总觉得我没有很好地使用这门语言。

我想在大矩阵上优化度量的计算，最好不使用循环。这是我的尝试：

ComputeVariance <- function(x, Delta, WindowSize, type){
  # Compute GramMatrix
  GramMatrix = outer(x, x, Kernel, Delta, type)
  Variance = vector("numeric", length(x))
  # Index of the points to compute the variance on these points 
  Index = seq(WindowSize/2, length(x) - WindowSize, by = WindowSize)

  for (i in Index){
    # Extraction of the sub-matrix useful to computations
    SubMat=GramMatrix[(i - WindowSize/2 + 1):(i + WindowSize/2),(i - WindowSize/2 + 1):(i + WindowSize/2)] 
    SubMatWithoutDiag = SubMat - diag(diag(SubMat))
    Variance[i] = sum(diag(SubMat))/WindowSize - sum(apply(SubMatWithoutDiag, 1, sum))/(WindowSize*(WindowSize - 1))
  }
  return(Variance) 
}