试试这个:
数据:
from <- c("A", "B", "F", "Q", "T", "S", "D", "E", "A", "T", "F")
to <- c("E", "D", "Q", "S", "F", "T", "B", "A", "D", "A", "E")
df <- data_frame(from, to)
代码:
recursive_IND <-
1:nrow(df) %>%
sapply(function(x){
if(any((as.character(df[x,]) == t(df[,c(2,1)])) %>% {.[1,] & .[2,]}))
return(T) else return(F)
})
df[recursive_IND,][!(df[recursive_IND,] %>% apply(1,sort) %>% t %>% duplicated(.)),]
df[!recursive_IND,]
结果:
# A tibble: 2 x 2
# from to
# <chr> <chr>
#1 A E
#2 B D
# A tibble: 7 x 2
# from to
# <chr> <chr>
#1 F Q
#2 Q S
#3 T F
#4 S T
#5 A D
#6 T A
#7 F E