Change value in row according to last occurrence-CodePudding

I have this data frame

 df <- data.frame(
        Machine_ID= c(1,1,1,1,2,2,2,2,2,2,3,3,3),
        Operation = c("Start", "Stop", "Start", "Stop", "Stop", "Stop", "Start", "Stop", "Start", "Stop", "Start", "Stop", "Start"))

> df
   Machine_ID Operation
1           1     Start
2           1      Stop
3           1     Start
4           1      Stop
5           2      Stop
6           2      Stop
7           2     Start
8           2      Stop
9           2     Start
10          2      Stop
11          3     Start
12          3      Stop
13          3     Start

And I would like to correct a sequence of operation. Every machine should have an even number of operation with combination of one Start and one End.

So I would like to have df like this

> df
   Machine_ID Operation
1           1     Start
2           1      Stop
3           1     Start
4           1      Stop
5           2      Start
6           2      Stop
7           2     Start
8           2      Stop
9           2     Start
10          2      Stop
11          3     Start
12          3      Stop
13          3     Start
14          3      Stop

I tried make a loop with IF statements, but its not optimal solution for my databse.

CodePudding user response：

Machine_ID <- rep(1:4,each=4)
Operation <- rep(c("Start", "Stop"),8)

df<-cbind.data.frame(Machine_ID,Operation)

CodePudding user response：

Here is one way to generate an even number of rows for each machine id, if the sequence is of odd value then it adds one additional row

tmp=tapply(df$Operation,df$Machine_ID,length)
tmp=ceiling(tmp/2)*2

data.frame(
  "Machine_ID"=rep(names(tmp),tmp),
  "Operation"=c("Start","Stop")
)