Message-ID: <201207252006.q6PK64BF011881@hypatia.math.ethz.ch>
Date: 2012-07-25T20:05:48Z
From: Jeff
Subject: Simple question on finding duplicates
I'm trying to find duplicate values in a column of a data frame. For
example, dataframe (a) below has two 3's. I would like to mark each value of
each row as either not being a duplicate of the one before (0), or as a
duplicate (1) - for example, as in dataframe (b). In SPSS, I would simply
compare each value to it's "lagged" value, but I can't figure out how to do
this with R.
Can someone point me in the right direction?
Thanks
a <- data.frame( col1 = c(1,2,3,3,4))
b <- data.frame( col1 = c(1,2,3,3,4), duplicate = c(0,0,0,1,0))