I have a data set of this format
User
1
2
3
2
3
1
1
Now I want to add a column saying count which counts the occurrence of the user. I want output in the below format.
User Count
1 1
2 1
3 1
2 2
3 2
1 2
1 3
I have few solutions but all those solutions are somewhat slow.
My data.frame has 100,000 rows now and soon it may go up to 1 million. I need a solution which is also fast.
You can use getanID from my "splitstackshape" package:
library(splitstackshape)
getanID(mydf, "User")
## User .id
## 1: 1 1
## 2: 2 1
## 3: 3 1
## 4: 2 2
## 5: 3 2
## 6: 1 2
## 7: 1 3
This is essentially an approach with "data.table" that looks something like the following:
as.data.table(mydf)[, count := seq(.N), by = "User"][]