> diam<- c(13.3, 13.7, 13.8, 14, 14.2, 14.5, 16, 16.3, 17.3, 17.5, 17.9, 18, 18, 20.6)
> alt<- c(86, 71, 64, 78, 80, 74, 72, 77, 81, 82, 80, 80, 80, 87)
> vol<- c(27.4, 25.7, 24.9, NA, 31.7, 36.3, 38.3, 42.6, 55.4, 55.7, 58.3, NA, 51, 77)
> var<- c("A", "R", "R", "A", "A", "R", "R", "R", "B", "B", "A", "R", "B", "R")
> RegB<- data.frame (diam, alt, vol, var)
> RegB
   diam alt  vol var
1  13.3  86 27.4   A
2  13.7  71 25.7   R
3  13.8  64 24.9   R
4  14.0  78   NA   A
5  14.2  80 31.7   A
6  14.5  74 36.3   R
7  16.0  72 38.3   R
8  16.3  77 42.6   R
9  17.3  81 55.4   B
10 17.5  82 55.7   B
11 17.9  80 58.3   A
12 18.0  80   NA   R
13 18.0  80 51.0   B
14 20.6  87 77.0   R