将map_dbl输出转换为R tidyverse中的tibble

Question

我在R中处理大量数据帧，我想找到列数最小和最大的数据帧，并找出它们列名的差异。然而，我在将map_dbl结果转换为常规tibble时遇到了困难。

first_df   = data.frame(matrix(rnorm(20), nrow=10))
second_df  = data.frame(matrix(rnorm(20), nrow=4))
third_df   = data.frame(matrix(rnorm(20), nrow=5))
library(dplyr)
library(purrr)
library(tibble)
library(tidyr)
# capturing all the data frames
mget(ls(pattern = "_df"))  %>% 
map_dbl(ncol)      %>% 
as_tibble() 

# expected output
# first_df   2
# second_df  5
## Finding the difference in columns
diff <- setdiff(colnames(first_df), colnames(second_df ))

Answer 1

你可以做：

library(tidyverse)
min_max <- mget(ls(pattern = "_df")) %>%
map_dbl(ncol) %>%
enframe() %>%
arrange(value) %>%
slice(1, n())
min_max
# A tibble: 2 x 2
#  name      value
#  <chr>     <dbl>
#1 first_df      2
#2 second_df     5
setdiff(names(get(min_max$name[2])), names(get(min_max$name[1])))
#[1] "X3" "X4" "X5"