duplicated rows

library(data.table)
library(plyr)
library(dplyr)
library(magrittr)
tbl_left = data.table(ID = 1:1821350, matrix(rnorm(23*1821350), 1821350))
tbl_right = data.table(matrix(rnorm(23*1289), 1289))
ID_right = sample(1:1821350, 1289-130)
ID_right = c(ID_right, sample(ID_right, 130, TRUE))
tbl_right %<>% mutate(ID = ID_right)
tbl_joined <- dplyr:::left_join(tbl_left, tbl_right, by = "ID")
tbl_joined %>% nrow # 1821480
## 1
tbl_right %>% select(ID) %>% distinct %>% nrow %>% subtract(1289) # -130
## 2
right_ID <- tbl_right %>% select(ID)
right_ID_dup = right_ID %>% filter(right_ID %>% duplicated())
right_ID_dup_sort = right_ID_dup %>% arrange(ID)
right_ID_dup_sort %>% nrow # 130
## 3
comm_ID = right_ID_dup %>% distinct %>%
  rbind(tbl_left %>% select(ID) %>% distinct)
comm_ID = comm_ID %>% filter(comm_ID %>% duplicated)
comm_ID %>% nrow # 127
## 4
tbl_right_ID = table(tbl_right$ID)
tbl_right_ID[match(comm_ID$ID, names(tbl_right_ID))] %>% sum # 257