R get rid of rows with duplicate attribute

Answer 1

subset(data,!duplicated(data$ID))

Should do the trick

Answer 2

If you want to keep one row for each ID, but there is different data on each row, then you need to decide on some logic to discard the additional rows. For instance:

df <- data.frame(ID=c(1, 2, 2, 3), time=1:4, OS="Linux")
df
  ID time    OS
1  1    1 Linux
2  2    2 Linux
3  2    3 Linux
4  3    4 Linux

Now I will keep the maximum time value and the last OS value:

library(plyr)
unique(ddply(df, .(ID), function(x) data.frame(ID=x[,"ID"], time=max(x$time), OS=tail(x$OS,1))))
  ID time    OS
1  1    1 Linux
2  2    3 Linux
4  3    4 Linux

Answer 3

Hi Shane,

Could you possibly describe what the function is doing? I have a similar problem to CatholicEvangelist, but it is a bit more complex and I think understanding yours would be helpful.

Thanks, Lauren