Message-ID: <77EB52C6DD32BA4D87471DCD70C8D7000442EFF6@NA-PA-VBE03.na.tibco.com>
Date: 2011-05-24T19:22:21Z
From: William Dunlap
Subject: Order a matrix
In-Reply-To: <1306263620107-3547923.post@n4.nabble.com>
Try using do.call("order", listOfColumnsToSortBy), as in
cols <- c(1,3,4)
x[do.call("order", as.data.frame(x[,cols])), ]
To be really safe you should remove the names from the data.frame
produced by as.data.frame (in case they match the argument names
of order), as in
x[do.call("order", unname(as.list(as.data.frame(x[,cols])))),]
or
x[do.call("order", unname(split(x[,cols], col(x[,cols])))), ]
Bill Dunlap
Spotfire, TIBCO Software
wdunlap tibco.com
> -----Original Message-----
> From: r-help-bounces at r-project.org
> [mailto:r-help-bounces at r-project.org] On Behalf Of Lisa
> Sent: Tuesday, May 24, 2011 12:00 PM
> To: r-help at r-project.org
> Subject: [R] Order a matrix
>
> Dear all,
>
> I just want to order a matrix using several columns in a matrix. For
> example:
>
> x <- matrix(sample(c(1:5), 60, replace = T), 10, 6).
>
> If I order the matrix by the first two columns, I will do it
> like this:
>
> x[order(x[, 1], x[, 2]), ].
>
> But when I repeat this work many times and the columns will
> change each time
> in a simulation study, how can I assign the arguments of order()? For
> example, in the first iteration, the columns needing to order
> is the first
> two columns, in the second iteration, the columns needing to
> order is the
> first, second, and fourth column? ....
>
> I would appreciate any help on this question. Thanks a lot.
>
> Lisa
>
>
> --
> View this message in context:
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>
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