R - 如何通过索引向量获取多维数组的值

Question

假设我有一个名为 pi 的多维数组，并且直到运行时才知道它的维数:

dims <- rep(3, dim_count)
pi <- array(0, dims)

如您所见，维度计数取决于 dim_count。当我有索引向量时，如何从数组中检索值？例如当我有:

dim_count <- 5
indexes <- c(1, 2, 3, 3, 3)

我要找回

pi[1, 2, 3, 3, 3]

有没有一种简短、有效且优雅的方法来做到这一点？

Answer 1

利用[的鲜为人知的用法:

When indexing arrays by [ a single argument i can be a matrix with as many columns as there are dimensions of x; the result is then a vector with elements corresponding to the sets of indices in each row of i.

你可以简单地做:

pi[matrix(indexes, 1)]