[R] matching matrix columns to a vector
Jagat.K.Sheth at wellsfargo.com
Jagat.K.Sheth at wellsfargo.com
Mon Nov 24 21:08:52 CET 2008
Yes! my oversight ... thank you
-----Original Message-----
From: David Winsemius [mailto:dwinsemius at comcast.net]
Sent: Monday, November 24, 2008 11:48 AM
To: Sheth, Jagat K
Cc: aks2515 at uncw.edu; r-help at r-project.org
Subject: Re: [R] matching matrix columns to a vector
Since negative values could balance positives, you might need to use:
which(colSums(abs(t-v)) == 0)
> t=matrix(1:12,3,4)
> v=c(1,2,3)
> which(colSums(t-v) == 0)
[1] 1
> t
[,1] [,2] [,3] [,4]
[1,] 1 4 7 10
[2,] 2 5 8 11
[3,] 3 6 9 12
> t[1,2] <- -5
> which(colSums(t-v) == 0)
[1] 1 2
> which(colSums(abs(t-v)) == 0)
[1] 1
--
David Winsemius
Heritage Labs
On Nov 24, 2008, at 11:59 AM, <Jagat.K.Sheth at wellsfargo.com>
<Jagat.K.Sheth at wellsfargo.com > wrote:
> How about which(colSums(t-v) == 0) ?
>
> -----Original Message-----
> From: r-help-bounces at r-project.org
> [mailto:r-help-bounces at r-project.org
> ]
> On Behalf Of Salas, Andria Kay
> Sent: Monday, November 24, 2008 10:04 AM
> To: r-help at r-project.org
> Subject: [R] matching matrix columns to a vector
>
> I need help with (hopefully) just one more thing. I have been fussing
> with this for quite some time and have decided just to give up and
> ask!
> I want to match a column in a matrix to a vector. I found a "which"
> command that I thought would be helpful as it does the following:
>
>> g=c(1,5,3,2,7)
>> which(g==5)
> [1] 2
>
> As the above gave which placement in the g vector corresponded to 5
> (the second place), I need this command to give me which column in a
> matrix matches to a vector.
>
> This is just a toy example of what I am trying to do:
>> t=matrix(1:12,3,4)
>> v=c(1,2,3)
>> which(t[,j]==v)
>
> This does not work, and with my "real" matrices and vectors, I was
> getting outputs that did not make sense. These examples are more to
> give an idea of what I am aiming to accomplish.
>
> Thank you for all the help!!
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> R-help at r-project.org mailing list
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> PLEASE do read the posting guide
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> and provide commented, minimal, self-contained, reproducible code.
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