Вот еще одно решение.
library(dplyr)
column_1=c("hi", "text", "text2", "halo", "hi", "test", "ok" )
column_2 =c("user1", "user1", "user1", "user2", "user2","user3", "user1")
df = data.frame(column_1, column_2)
group_by(df, column_2) %>%
summarise(count=n()) %>%
head()
Вывод:
column_2 count
<fct> <int>
1 user1 4
2 user2 2
3 user3 1