Create indicator variable within panel data in R

Question

I feel this should be easy but at a loss, and hoping y'all can help. I have panel data, by id with variables, here just v1:

id  v1
A   14
A   15
B   12
B   13
B   14 
C   11
C   12 
C   13
D   14

I would simply like to create a dummy variable indicating whether a value of v1 (say 12) exists in the panel for id. So something like:

id  v1  v2
A   14  0
A   15  0 
B   12  1
B   13  1
B   14  1 
C   11  1
C   12  1 
C   13  1
D   14  0

I feel this should be simple but can't figure out an easy one line solution.

Many many thanks!

Answer 1

Try

library(dplyr)
df %>% group_by(id) %>% mutate(v2 = as.numeric(any(v1 == 12)))

Or as per @akrun suggestion:

library(data.table)
setDT(df)[, v2 := any(v1 ==12)+0L, id]

Note: Adding 0L to the logical values created by any() will switch TRUE/FALSE to 0s and 1s.

Another approach could be using ave:

df$v2 <- with(df, ave(v1, id, FUN = function(x) any(x == 12)))

Which gives:

#  id v1 v2
#1  A 14  0
#2  A 15  0
#3  B 12  1
#4  B 13  1
#5  B 14  1
#6  C 11  1
#7  C 12  1
#8  C 13  1
#9  D 14  0