rollapply 二维数组 (R) [英] rollapply for two-dimensional arrays (R)

问题描述

我想做一些事情，我认为使用 rollapply 应该很容易实现，但我遇到了一些麻烦.

There is something I want to do which I believe should be easily achieved with rollapply, but I am having some trouble.

对于简单的向量，我们有

For simple vectors we have

> a <- c(1:10)
> a
 [1]  1  2  3  4  5  6  7  8  9 10
> rollapply(a, 2, mean)
 [1] 1.5 2.5 3.5 4.5 5.5 6.5 7.5 8.5 9.5

这是应该的.但是对于更高的维度会出现问题

which is as it should be. But problems arise for higher dimensions

> b <- array(c(1:6), c(2,3))
> b
     [,1] [,2] [,3]
[1,]    1    3    5
[2,]    2    4    6
> rollapply(b, 2, mean)
     [,1] [,2] [,3]
[1,]  1.5  3.5  5.5

如果我想要应用于列，这很好 - 但肯定也必须有某种方法可以应用于行并获得

which is fine if I want to apply over columns - but surely there must also be some way to apply over rows instead and get

     [,1] [,2]
[1,]    2    4
[2,]    3    5

rollapply 函数无法做到这一点，我可以看到.

The rollapply function offers no way to do this that I can see.

推荐答案

我们可以简单地使用 apply 和 MARGIN = 1 循环遍历行并应用 滚动应用.MARGIN 也可以针对更高的维度进行调整，即它是更通用的解决方案

We can simply use apply with MARGIN = 1 to loop over the rows and apply the rollapply. The MARGIN can be adjusted for higher dimensions as well i.e. it is more general solution

t(apply(b, 1, function(x) rollapply(x, 2, mean)))

-输出

#      [,1] [,2]
#[1,]    2    4
#[2,]    3    5

---

或使用 collapse

library(collapse)
dapply(b, FUN = function(x) rollapply(x, 2, fmean), MARGIN = 1)

这篇关于rollapply 二维数组 (R)的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！