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

Here's how I hope your data is really set up

df <- data.frame (id = c(rep("a", 3), rep("b", 2), "r"),
                  val1 = c(2, 3, 3, 1, 2, 4), val2 = c(3, 4, 5, 3, 6, 5))

You could do a split-unsplit

> unsplit(lapply(split(df, df$id), function(x) {
      if(nrow(x) > 1) {
          x[duplicated(x$id) & x$val2 == max(x$val2),]
      } else {
          x
      }
  }), levels(df$id))
#   id val1 val2
# 3  a    3    5
# 5  b    2    6
# 6  r    4    5

You can also use Reduce(rbind, ...) or do.call(rbind, ...) in place of unsplit