r - Add column with order counts

Question

How do I add a column to my data frame that states the order count of occurrences of a value in another column? This is what I want the result to look like:

   Fruit orderCount
1 Orange          1
2 Banana          1
3 Orange          2
4  Apple          1
5 Orange          3
6 Banana          2

For the first observation of a value in the column Fruit, I want the corresponding orderCount to be 1, for the second observation 2 and so on.

Thanks for any help.

Answer 1

You can try getanID from my "splitstackshape" package:

library(splitstackshape)
getanID(mydf, "Fruit")
#     Fruit .id
# 1: Orange   1
# 2: Banana   1
# 3: Orange   2
# 4:  Apple   1
# 5: Orange   3
# 6: Banana   2

In base R, you can use ave with seq_along for the aggregation function.