Count number of occurences for each unique value

If you have multiple factors (= a multi-dimensional data frame), you can use the dplyr package to count unique values in each combination of factors:

library("dplyr")
data %>% group_by(factor1, factor2) %>% summarize(count=n())

It uses the pipe operator %>% to chain method calls on the data frame data.

Perhaps table is what you are after?

dummyData = rep(c(1,2, 2, 2), 25)

table(dummyData)
# dummyData
#  1  2 
# 25 75

## or another presentation of the same data
as.data.frame(table(dummyData))
#    dummyData Freq
#  1         1   25
#  2         2   75

It is a one-line approach by using aggregate.

> aggregate(data.frame(count = v), list(value = v), length)

  value count
1     1    25
2     2    75