如何构建更复杂的矢量化操作？

I have a sublist of principal component rotation vectors computed by prcomp, where each list item is an Nx2 array (i.e., two column vectors), for each class.

我有一个由prcomp计算的主分量旋转矢量的子列表，其中每个列表项是每个类的Nx2数组（即两个列向量）。

Using those vectors, I'd like to project some data similarly structured into a list of classes, each class item containing arrays with dimension NxMxT, where T is the number of trials.

使用这些向量，我想将类似结构的一些数据投影到类列表中，每个类项包含具有维度NxMxT的数组，其中T是试验次数。

My problem is, I can write simple vectorized functions with apply and its variants, but I'm having trouble generalizing this to apply that over each list.

我的问题是，我可以使用apply及其变体编写简单的向量化函数，但是我很难将其概括为将其应用于每个列表。

Example data:

示例数据：

somedata <- list(array(rnorm(100),dim=c(5,4,5)),array(rnorm(100),dim=c(5,4,5)))
somevectors <- list(array(rnorm(10),dim=c(5,2)),array(rnorm(10),dim=c(5,2)))

Here is a simple example of the operation over each list element:

以下是对每个列表元素的操作的简单示例：

o.proj.1 <- apply(somedata[[1]],3,function(x){
    t(somevectors[[1]]) %*% x
  }) # returns an array where each projected trial is a column

I tried fitting this inside a call to lapply(), but didn't find much success:

我尝试在调用lapply（）时调整它，但没有找到太多成功：

lapply(somedata, y = somevectors, function(x,y){
  apply(x,3,function(z){
    t(y) %*% z
  })
})

Error in t(y) %*% z : requires numeric/complex matrix/vector arguments

Basically my algorithm is to put the appropriate apply type (here lapply) around the more local function and remove the index that will be vectorized (here [[]]). What am I missing?

基本上我的算法是在更多局部函数周围放置适当的apply类型（这里是lapply）并删除将被矢量化的索引（这里[[]]）。我错过了什么？

1 个解决方案

#1

Of the *apply family of functions, mapply is the one to use when you want to loop simultaneously over two or more objects. Try:

在* apply系列函数中，当你想在两个或多个对象上同时循环时，mapply就是一个。尝试：

o.proj <- mapply(function(x,y){
  apply(x,3,function(z){
    t(y) %*% z
  })
}, somedata, somevectors, SIMPLIFY = FALSE)

I suppose you will want to use SIMPLIFY = FALSE to return a list, otherwise mapply will attempt to simplify your output into an array, a little like sapply does.

我想你会想要使用SIMPLIFY = FALSE来返回一个列表，否则mapply会尝试将输出简化为数组，有点像sapply。

Also know that you can use Map as a shortcut for mapply(..., SIMPLIFY = FALSE).

还要知道您可以使用Map作为mapply的快捷方式（...，SIMPLIFY = FALSE）。

#1