Message-ID: <3CC20FC2-99F0-49C5-A56A-0AC1431AAFA0@gmail.com>
Date: 2012-08-03T07:31:53Z
From: Peter Dalgaard
Subject: all duplicated wanted
In-Reply-To: <E67F2D0E-9C82-4233-BFDA-36D8D891F4DC@gmail.com>
On Aug 3, 2012, at 09:06 , Weijia Wang wrote:
> Hi,
>
> Has anyone been able to figure out how to print all duplicated observations?
>
> I have a dataset, with patients ID, and other lab records.
>
> Some patients have multiple lab records, but 'duplicated' ID will only show me the duplicates, not the original observation.
>
> How can I print both the original one and the duplicates?
Something like this?
dd[ID %in% unique(ID[duplicated(ID)]),]
Let's try:
> ID <- sample(1:10, 10, replace=TRUE)
> table(ID)
ID
1 2 3 4 7 10
1 1 3 1 2 2
> ID[ID %in% unique(ID[duplicated(ID)])]
[1] 7 7 10 3 3 3 10
The unique() bit is really just for efficiency:
> ID[ID %in% ID[duplicated(ID)]]
[1] 7 7 10 3 3 3 10
--
Peter Dalgaard, Professor,
Center for Statistics, Copenhagen Business School
Solbjerg Plads 3, 2000 Frederiksberg, Denmark
Phone: (+45)38153501
Email: pd.mes at cbs.dk Priv: PDalgd at gmail.com