A <- data.table::fread(
"name id sub
a 1 ach
c 2 wrb
h 3 xjk
d 4 iuc"
)
B <- data.table::fread(
"name id sub
b 1 xcv
d 2 wrb
f 3 kjj
j 4 lcb"
)
## table
table(rbind(A,B)[,'sub'])
#>
#> ach iuc kjj lcb wrb xcv xjk
#> 1 1 1 1 2 1 1
## duplicated
duplicated(rbind(A,B)[,'sub'])
#> [1] FALSE FALSE FALSE FALSE FALSE TRUE FALSE FALSE
## using dplyr
library(dplyr)
rbind(A,B) %>%
group_by(sub) %>%
summarise(n=n()) %>%
filter(n >1)
#> # A tibble: 1 x 2
#> sub n
#> <chr> <int>
#> 1 wrb 2
<sup>Created on 2018-10-10 by the reprex package (v0.2.1)</sup>