R purrr 映射在输出中显示列名 [英] R purrr map show column names in output

问题描述

我正在尝试跨向量输入运行 purrr map，在输出中我希望输出列具有有意义的名称.

I'm trying to run purrr map across vector inputs, and in the output i'd like the output columns to have meaningful names.

x <- c("a", "b")
y <- "end."

map_dfc(x, function(x) paste("pre ", x, y))

names(x) <- x
map_dfc(x, function(x) paste(x, y))

这是我期望的输出，它有列名 a 和 b:

This is the output I expect, which has column names a and b:

# A tibble: 1 x 2
# a      b     
# <chr>  <chr> 
# pre  a end. pre  b end.

有没有办法避免运行的需要

Is there a way to avoid the need to run

names(x) <- x

即

x <- c("a", "b")
y <- "end."

map_dfc(x, function(x) paste("pre ", x, y))
# A tibble: 1 x 2
# a      b     
# <chr>  <chr> 

生成已附加列名称的 data.frame/tibble?

yields the data.frame/tibble with column names already attached?

我经常使用地图，但经常忘记输入向量是否有名称.

I use map alot and often forget if the input vector has names or not.

推荐答案

purrr 的方式是使用 set_names 作为注释，(尽管正确的 setNames 似乎被 purrr 中的 set_names 替换了):

The purrr way is to use set_names as in the comments, (although correct setNames seems to be replaced by set_names in purrr):

map_dfc(set_names(x), function(x) paste("pre ", x, y))

使用 set_names 如果使用默认参数，则无需指定新名称.

With set_names you don't need to specify the new names if you use the default argument.

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