[R] Remove rows that have repeated items in a particular column

[MK]

Very simple

mat[!duplicated(mat[, 1]), ]

M

On 26/07/12 06:50, Zhongyi Yuan wrote:
> Dear R Users,
>
> I apology for not being able to provide an adequately informative subject.
> Let me describe my problem with an example.
>
> For a matrix
> *    (mat <- matrix(c(1,1,2,2,2,3,3, 5,9,1,3,7,4,8), ncol = 2))*
> my desired output is
> *    (desired <- matrix(c(1,2,3, 5,1,4), ncol = 2))*
>
> That is, the first column is numerically grouped and only the first item in
> each group is wanted.  The second column is in increasing order within each
> group.  My actual data will be of size 10^6 by 100 so I am hoping to solve
> this by a simple function.  Thank you very much for your help.
>
> Best,
> Zhongyi Yuan
>
> 	[[alternative HTML version deleted]]
>
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