Am kindly looking for R code that can calculate the combinations with 2, of the total in each group.
library(dplyr)
id<-c(1,1,1,1,2,2,2,2,3,3,3,3)
sex<-c(1,1,1,1,1,1,1,1,1,1,1,1)
ds<-data.frame(id,sex)
out1<-ds %>% group_by(id) %>% summarise(n=n())
My output should be
id<-c(1,2,3)
n<-c(4,4,4)
ncomb2<-c(6,6,6)
Thankyou
I am not sure if the code below is what you are after
out1 <- ds %>%
group_by(id) %>%
summarise(n = n()) %>%
mutate(ncomb2 = choose(n,2))
such that
> out1
# A tibble: 3 x 3
id n ncomb2
<dbl> <int> <dbl>
1 1 4 6
2 2 4 6
3 3 4 6