R help - Feb 2007 - Dealing with Duplicates - How to count instances?

Hi there,

given a data.frame 'data' I managed to filter out entries (rows) that
are
identical with respect to one column like so:

duplicity <- duplicated(data[column])
data_unique <- subset(data,duplicity!=TRUE)

But I'm trying to extract how many duplicates each of the remaining rows
had.

Can someone please send me down the right path for this?

Joh

table(data[column])

will give you the number of items in each subgroup; that would be the
count you are after.

On 2/2/07, Johannes Graumann <johannes_graumann at web.de>
wrote:
> Hi there,
>
> given a data.frame 'data' I managed to filter out entries (rows)
that are
> identical with respect to one column like so:
>
> duplicity <- duplicated(data[column])
> data_unique <- subset(data,duplicity!=TRUE)
>
> But I'm trying to extract how many duplicates each of the remaining
rows
> had.
>
> Can someone please send me down the right path for this?
>
> Joh
>
> ______________________________________________
> R-help at stat.math.ethz.ch mailing list
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> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>

-- 
Jim Holtman
Cincinnati, OH
+1 513 646 9390

What is the problem you are trying to solve?

jim holtman wrote:
> table(data[column])
> 
> will give you the number of items in each subgroup; that would be the
> count you are after.
Thanks for your Help! That rocks! I can do 

copynum <- table(data_6plus["Accession.number"])
data_6plus$"Repeats" <-
sapply(data_6plus[["Accession.number"]], function(x)
   copynum[x][[1]])

now!

But how about this:
- do something along the lines of 

duplicity <- duplicated(data_6plus["Accession.number"])
data_6plus_unique <- subset(data_6plus,duplicity!=TRUE)

- BUT: retain from each deleted row one field, append it to a vector and
fill that into a new field of the remaining row of the set sharing
data_6plus["Accession.number"]?

How would you do something like that?

Joh