Receive the total sum score of every number

Question

Using as input data frame:

df1 <- data.frame(num = c(1,1,1,2,2,2,3))

How is it possible to receive the sum of every number excited in the num column?

Example output:

num frequency
1 3
2 3
3 1

Answer 1

Using table and coerce it to a data frame.

as.data.frame(table(df1$num))
#   Var1 Freq
# 1    1    3
# 2    2    3
# 3    3    1

or

with(df1, data.frame(num=unique(num), freq=tabulate(num)))
#   num freq
# 1   1    3
# 2   2    3
# 3   3    1