I am trying to create an additional variable (new variable-> flag) that will number the repetition of observation in my variable starting from 0.
dataset <- data.frame(id = c(1,1,1,2,2,4,6,6,6,7,7,7,7,8))
intended results will look like:
id flag
1 0
1 1
1 2
2 0
2 1
4 0
6 0
6 1
6 2
7 0
7 1
7 2
7 3
8 0
Thank You!
You may try
dataset$flag <- unlist(sapply(rle(dataset$id)$length, function(x) seq(1,x)-1))
id flag
1 1 0
2 1 1
3 1 2
4 2 0
5 2 1
6 4 0
7 6 0
8 6 1
9 6 2
10 7 0
11 7 1
12 7 2
13 7 3
14 8 0
data.table:
library(data.table)
setDT(dataset)[, flag := rowid(id) - 1]
dataset
id flag
1: 1 0
2: 1 1
3: 1 2
4: 2 0
5: 2 1
6: 4 0
7: 6 0
8: 6 1
9: 6 2
10: 7 0
11: 7 1
12: 7 2
13: 7 3
14: 8 0
Base R:
dataset$flag = sequence(rle(dataset$id)$lengths) - 1
dataset
id flag
1 1 0
2 1 1
3 1 2
4 2 0
5 2 1
6 4 0
7 6 0
8 6 1
9 6 2
10 7 0
11 7 1
12 7 2
13 7 3
14 8 0
Another base option:
transform(dataset,
flag = Reduce(function(x, y) y * x + y, duplicated(id), accumulate = TRUE))
id flag
1 1 0
2 1 1
3 1 2
4 2 0
5 2 1
6 4 0
7 6 0
8 6 1
9 6 2
10 7 0
11 7 1
12 7 2
13 7 3
14 8 0
dplyr -
library(dplyr)
dataset %>% group_by(id) %>% mutate(flag = row_number() - 1)
# id flag
# <dbl> <dbl>
# 1 1 0
# 2 1 1
# 3 1 2
# 4 2 0
# 5 2 1
# 6 4 0
# 7 6 0
# 8 6 1
# 9 6 2
#10 7 0
#11 7 1
#12 7 2
#13 7 3
#14 8 0
Base R with similar logic
transform(dataset, flag = ave(id, id, FUN = seq_along) - 1)
another way to reach what you expect but writing a little more
x <- dataset %>%
group_by(id) %>%
summarise(nreg=n())
df <- data.frame()
for(i in 1:nrow(x)){
flag <- data.frame(id = rep( x$id[i], x$nreg[i] ),
flag = seq(0, x$nreg [i] -1 )
)
df <- rbind(df, flag)
}
