添加 NA 以使所有列表元素长度相等 [英] Add NAs to make all list elements equal length

问题描述

我在 dplyr、tidyr 中做了一系列的事情，所以如果可能的话，我想保留一个管道解决方案.

I'm doing a series of things in dplyr, tidyr, so would like to keep with a piped solution if possible.

我有一个每个组件中元素数量奇数的列表:

I have a list with uneven numbers of elements in each component:

lolz <- list(a = c(2,4,5,2,3), b = c(3,3,2), c=c(1,1,2,4,5,3,3), d=c(1,2,3,1), e=c(5,4,2,2))
lolz
$a
[1] 2 4 5 2 3

$b
[1] 3 3 2

$c
[1] 1 1 2 4 5 3 3

$d
[1] 1 2 3 1

$e
[1] 5 4 2 2

我想知道是否有一个整洁的一个衬里来用 NA 填充每个元素，这样它们的长度都与具有最大项目的元素相同:

I am wondering if there's a neat one liner to fill up each element with NAs such that they all are of the same length as the element with the maximum items:

我有一个 2 衬里:

lolz %>% lapply(length) %>% unlist %>% max -> mymax
lolz %>% lapply(function(x) c(x, rep(NA, mymax-length(x))))


$a
[1]  2  4  5  2  3 NA NA

$b
[1]  3  3  2 NA NA NA NA

$c
[1] 1 1 2 4 5 3 3

$d
[1]  1  2  3  1 NA NA NA

$e
[1]  5  4  2  2 NA NA NA

想知道我是否遗漏了更快/更优雅的东西.

Wondering if I'm missing something quicker / more elegant.

推荐答案

你可以使用

lapply(lolz, `length<-`, max(lengths(lolz)))
# $a
# [1]  2  4  5  2  3 NA NA
# 
# $b
# [1]  3  3  2 NA NA NA NA
# 
# $c
# [1] 1 1 2 4 5 3 3
# 
# $d
# [1]  1  2  3  1 NA NA NA
# 
# $e
# [1]  5  4  2  2 NA NA NA

或

n <- max(lengths(lolz))
lapply(lolz, `length<-`, n)

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