Remove duplicates based on 2nd column condition

Question

I am trying to remove duplicate rows from a data frame based on the max value on a different column

So, for the data frame:

df<-data.frame (rbind(         


        

Answer 1

One possible way is to use data.table

library(data.table)
setDT(df)[, .SD[which.max(val2)], by = id]
##    id val1 val2
## 1:  a    3    5
## 2:  b    2    6
## 3:  r    4    5