在R中预分配列表 [英] preallocate list in R

问题描述

R在循环中扩展数据结构的效率很低.如何预分配一定大小的list? matrix通过ncol和nrow参数使此操作变得容易.如何在清单中做到这一点?例如:

It is inefficient in R to expand a data structure in a loop. How do I preallocate a list of a certain size? matrix makes this easy via the ncol and nrow arguments. How does one do this in lists? For example:

x <- list()
for (i in 1:10) {
    x[[i]] <- i
}

我认为这是无效的.有什么更好的方法?

I presume this is inefficient. What is a better way to do this?

推荐答案

vector可以创建具有所需模式和长度的空向量.

vector can create empty vector of the desired mode and length.

x <- vector(mode = "list", length = 10)

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