按变量分组后的相交元素

Question

我有如下数据：

toy.dat <- data.frame(group = c(rep("A_0", 3), rep("A_1", 2), 
                                rep("B_0", 3) , rep("B_1", 3)))
toy.dat$letters <- c("A", 'B', "C", "A", "D", "C", "E", "F", "A", "B", "F")

toy.dat %>% 
  group_by(group) %>% 
  summarise(letters = list(letters), num = n()) %>%
  mutate(group_number = gsub(".*_", "", group))


group   letters            num_elements  group_num   
A_0     c("A", "B", "C")       3              0        
A_1     c("A", "D")            2              1
B_0     c("C", "E", "F")       3              0
B_1     c("A", "B", "F")       3              1

我想按 group_numb 分组并找到这些行的字母交集并将它们添加到数据框中。

A_0 和 B_0 的输出应为“c”，A_1 和 B_1 的输出应为“A”。

Answer 1

我们可以用reduce

library(dplyr)
library(purrr)
toy.dat %>% group_by(group) %>% summarise(letters = list(letters), num = n()) %>%
mutate(group_number = gsub(".*_", "", group)) %>% group_by(group_number) %>% mutate(intersect = list(reduce(letters, intersect))) %>%
 ungroup %>%
   mutate(nintersect = lengths(intersect))

-输出

# A tibble: 4 × 6
  group letters     num group_number intersect nintersect
  <chr> <list>    <int> <chr>        <list>         <int>
1 A_0   <chr [3]>     3 0            <chr [1]>          1
2 A_1   <chr [2]>     2 1            <chr [1]>          1
3 B_0   <chr [3]>     3 0            <chr [1]>          1
4 B_1   <chr [3]>     3 1            <chr [1]>          1

按变量分组后的相交元素

intersecting elements after grouping by a variable

group-by

r

list

intersect

dplyr