子集不同数据类型的列表

I have a list of different data types (factors, data.frames, and vectors, all the same length or number of rows), What I would like to do is subset each element of the list by a vector (let's call it rows) that represents row names.

我有一个不同数据类型的列表（因子，data.frames和向量，所有相同的长度或行数），我想做的是通过向量对列表的每个元素进行子集（让我们称之为行）表示行名称。

If it was a data.frame() I would:

如果是data.frame（）我会：

x <- x[rows,]

If it was a vector() or factor() I would:

如果是vector（）或factor（），我会：

x <- x[rows]

So, I've been playing around with this:

所以，我一直在玩这个：

x <- lapply(my_list, function(x) ifelse(is.data.frame(x), x[rows,], x[rows]))

So, how do I accomplish my goal of getting a list of subsetted data?

那么，我如何实现获取子集数据列表的目标呢？

1 个解决方案

#1

I think this is YAIEP (Yet Another If Else Problem). From ?ifelse:

我认为这是YAIEP（还有另一个问题）。来自？ifelse：

ifelse returns a value with the same shape as test which is filled with elements selected from either yes or no depending on whether the element of test is TRUE or FALSE.

ifelse返回一个与test相同形状的值，该值填充了从yes或no中选择的元素，具体取决于test元素是TRUE还是FALSE。

See the trouble? Same shape as test.

看到麻烦？与测试相同的形状。

So just do this:

所以这样做：

l <- list(a = data.frame(x=1:10,y=1:10),b = 1:10, c = factor(letters[1:20]))

rows <- 1:3

fun <- function(x){
    if (is.data.frame(x)){
        x[rows,]
    }
    else{
        x[rows]
    }
}

lapply(l,fun)

#1