问题描述
我经常发现一些问题,人们以某种方式以 unnamed 字符向量的 unnamed 列表结尾,他们想将它们按行绑定到 data.frame
。例如:
I often find questions where people have somehow ended up with an unnamed list of unnamed character vectors and they want to bind them row-wise into a data.frame
. Here is an example:
library(magrittr)
data <- cbind(LETTERS[1:3],1:3,4:6,7:9,c(12,15,18)) %>%
split(1:3) %>% unname
data
#[[1]]
#[1] "A" "1" "4" "7" "12"
#
#[[2]]
#[1] "B" "2" "5" "8" "15"
#
#[[3]]
#[1] "C" "3" "6" "9" "18"
一种典型的方法是使用 do.call $
One typical approach is with do.call
from base R.
do.call(rbind, data) %>% as.data.frame
# V1 V2 V3 V4 V5
#1 A 1 4 7 12
#2 B 2 5 8 15
#3 C 3 6 9 18
也许从R到 Reduce
效率较低。
Reduce(rbind,data, init = NULL) %>% as.data.frame
# V1 V2 V3 V4 V5
#1 A 1 4 7 12
#2 B 2 5 8 15
#3 C 3 6 9 18
但是,当我们考虑使用更现代的软件包时,例如 dplyr
或 data.table
,由于向量未命名或不在列表中,因此可能立即想到的某些方法不起作用。
However, when we consider more modern packages such as dplyr
or data.table
, some of the approaches that might immediately come to mind don't work because the vectors are unnamed or aren't a list.
library(dplyr)
bind_rows(data)
#Error: Argument 1 must have names
library(data.table)
rbindlist(data)
#Error in rbindlist(data) :
# Item 1 of input is not a data.frame, data.table or list
一种方法可能是在向量上使用 set_names
。
One approach might be to set_names
on the vectors.
library(purrr)
map_df(data, ~set_names(.x, seq_along(.x)))
# A tibble: 3 x 5
# `1` `2` `3` `4` `5`
# <chr> <chr> <chr> <chr> <chr>
#1 A 1 4 7 12
#2 B 2 5 8 15
#3 C 3 6 9 18
但是,这似乎比需要的步骤更多。
However, this seems like more steps than it needs to be.
因此,我的问题是什么是有效的 tidyverse
或 data.table
方法将未命名字符向量的未命名列表按行绑定到 data.frame
?
Therefore, my question is what is an efficient tidyverse
or data.table
approach to binding an unnamed list of unnamed character vectors into a data.frame
row-wise?
推荐答案
不确定效率,而是使用 purrr
和 tibble
可以是:
Not entirely sure about efficiency, but a compact option using purrr
and tibble
could be:
map_dfc(purrr::transpose(data), ~ unlist(tibble(.)))
V1 V2 V3 V4 V5
<chr> <chr> <chr> <chr> <chr>
1 A 1 4 7 12
2 B 2 5 8 15
3 C 3 6 9 18
这篇关于Tidyverse方法按行绑定未命名向量的未命名列表-do.call(rbind,x)等效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!