[R] duplicated rows of a matrix

[William Dunlap]

duplicated(x), for vector or matrix x, flags any value (row for
matrices) previously seen in x.  To flag all duplicated values (rows
for matrices) you can use the following allDups() function.

   allDups <- function(x) duplicated(x) | duplicated(x, fromLast=TRUE)

> In your example, rows 2,3,4,5,8

Don't you want row 1 also, since rows 1 and 8 contain c(1,11)?  Or I
am again misinterpreting what you want?

Bill Dunlap
TIBCO Software
wdunlap tibco.com


On Mon, Jul 21, 2014 at 12:51 PM, carol white <wht_crl at yahoo.com> wrote:
> I need that duplicated indicate all row indices (occurences) that are
> duplicated. In your example, rows 2,3,4,5,8
>
> Thanks.
>
> Carol
>
>
> On Monday, July 21, 2014 9:17 PM, William Dunlap <wdunlap at tibco.com> wrote:
>
>
> Can you give an example of duplicated() not working on the rows of a matrix?
>
> Here is an example where it does work:
>> m <- cbind(c(a=1,b=2,c=3,d=2,e=3,f=4,g=1,h=1), c(11,13,11,13,11,13,13,11))
>> class(m)
> [1] "matrix"
>> m
>   [,1] [,2]
> a    1  11
> b    2  13
> c    3  11
> d    2  13
> e    3  11
> f    4  13
> g    1  13
> h    1  11
>> duplicated(m)
> [1] FALSE FALSE FALSE  TRUE  TRUE FALSE FALSE  TRUE
>> m[duplicated(m), ]
>   [,1] [,2]
> d    2  13
> e    3  11
> h    1  11
>
> Bill Dunlap
> TIBCO Software
> wdunlap tibco.com
>
>
> On Mon, Jul 21, 2014 at 7:54 AM, carol white <wht_crl at yahoo.com> wrote:
>> Hi,
>> is it possible to find the duplicated rows of a matrix without a loop or i
>> have to loop over the rows? duplicated doesn't seem to be helpful
>>
>> Thanks
>>
>> Carol
>
>>
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>>
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