Message-ID: <1343248008.47338.YahooMailNeo@web142604.mail.bf1.yahoo.com>
Date: 2012-07-25T20:26:48Z
From: arun
Subject: Simple question on finding duplicates
In-Reply-To: <201207252006.q6PK64BF011881@hypatia.math.ethz.ch>
HI,
Try this:
? a <- data.frame( col1 = c(1,2,3,3,4))
a<-within(a, duplicate<-c(0,ifelse(diff(a$col1)==0,1,0)))
?a
? col1 duplicate
1??? 1???????? 0
2??? 2???????? 0
3??? 3???????? 0
4??? 3???????? 1
5??? 4???????? 0
A.K.
----- Original Message -----
From: Jeff <r at jp.pair.com>
To: r-help at r-project.org
Cc:
Sent: Wednesday, July 25, 2012 4:05 PM
Subject: [R] 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))
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