Group persons based on birth of year in R

Question

I have the following dataset

df<- data.frame(x1=c(1,5,7,8,2,2,3,4,5,10),
birthyear=c(1992,1994,1993,1992,1995,1999,2000,2001,2000, 1994))

I want to group persons in 3-year intervals together so that persons born in 1992-1994 are group 1 and 1995-1997 are in group 2 and so on. I have a far larger dataset with over 10000 entries. How could I do it the most efficient way?

Answer 1

I would simply use cut with breaks defined with seq:

df$group <- cut(df$birthyear,
                seq(1992, 2022, 3),
                labels = F,
                right = F)
df

Output:

#>    x1 birthyear group
#> 1   1      1992     1
#> 2   5      1994     1
#> 3   7      1993     1
#> 4   8      1992     1
#> 5   2      1995     2
#> 6   2      1999     3
#> 7   3      2000     3
#> 8   4      2001     4
#> 9   5      2000     3
#> 10 10      1994     1

^{Created on 2022-05-03 by the reprex package (v2.0.1)}