将 map_dbl 输出转换为 R tidyverse 中的 tibble [英] converting map_dbl output to tibble in R tidyverse

问题描述

我在 R 中处理大量数据框，我想找到具有最小和最大列数的数据框，并找出它们列名的差异.但是，我在将 map_dbl 结果转换为常规 tibble 时遇到了困难.

I work with a large number of dataframes in R and I want to find the dataframes with the minimum and the maximum number of columns and finding the difference in their column names. However, I got stuck in turning my map_dbl results to a regular tibble.

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 ))

推荐答案

你可以:

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"

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