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Salas, Andria Kay

2008-Nov-24 16:03 UTC

[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!!

Jagat.K.Sheth at wellsfargo.com

2008-Nov-24 16:59 UTC

head link

[R] matching matrix columns to a vector

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!!
______________________________________________
R-help at r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.

David Winsemius

2008-Nov-24 17:47 UTC

head link

[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!!
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.

jim holtman

2008-Nov-24 18:01 UTC

head link

[R] matching matrix columns to a vector

You can use the arr.ind option of which:
> t=matrix(1:12,3,4)
> v=c(1,2,3)
> t     [,1] [,2] [,3] [,4]
[1,]    1    4    7   10
[2,]    2    5    8   11
[3,]    3    6    9   12> result <- sapply(v, function(x) which(t == x, arr.ind=TRUE))
> colnames(result) <- v
> result     1 2 3     # 'v'
[1,] 1 2 3    # row
[2,] 1 1 1    # column>

On Mon, Nov 24, 2008 at 11:03 AM, Salas, Andria Kay <aks2515 at uncw.edu>
wrote:> 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!!
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> 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 that you are trying to solve?

David Winsemius

2008-Nov-24 18:02 UTC

head link

[R] matching matrix columns to a vector

Consider:

 > apply(t,2,function(x)identical(x,v))
[1]  TRUE FALSE FALSE FALSE

 > apply(t,2,function(x)identical(x,v))+0
[1] 1 0 0 0

and if you wanted to get the position you could use which:
 > which(apply(t,2,function(x)identical(x,v)))
[1] 1

 > t[,4] <- v
 > which(apply(t,2,function(x)identical(x,v)))
[1] 1 4

--  
David Winsemius
On Nov 24, 2008, at 11:03 AM, Salas, Andria Kay wrote:
> 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!!
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.

Marc Schwartz

2008-Nov-24 18:04 UTC

head link

[R] matching matrix columns to a vector

on 11/24/2008 10:03 AM Salas, Andria Kay wrote:> 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!! 
Presuming that you are comparing integers or characters:

mat <- matrix(1:12, 3, 4)
Vec <- 1:3
> mat     [,1] [,2] [,3] [,4]
[1,]    1    4    7   10
[2,]    2    5    8   11
[3,]    3    6    9   12
> Vec[1] 1 2 3
> which(apply(mat, 2, identical, Vec))[1] 1


Another possible option:
> which(apply(mat, 2, function(x) all(x == Vec)))[1] 1


See ?apply, ?identical and ?all

Note that a variation on this would be required for floating point
numbers using all.equal().

You might also want to add error checking to be sure that:

  length(Vec) == nrow(mat)

lest you risk re-cycling of values.

HTH,

Marc Schwartz

Dan Davison

2008-Nov-24 20:06 UTC

head link

[R] matching matrix columns to a vector

Jagat.K.Sheth wrote:> 
> How about which(colSums(t-v) == 0) ?
> 
But what about v=c(2,1,3)? It needs to be something like

which(colSums((t - v)^2)) == 0
or
which(colSums(abs(t - v))) == 0

Dan


Jagat.K.Sheth wrote:> 
> -----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!!
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
> 
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
> 
> 
-- 
View this message in context:
http://www.nabble.com/matching-matrix-columns-to-a-vector-tp20664376p20668707.html
Sent from the R help mailing list archive at Nabble.com.

Jagat.K.Sheth at wellsfargo.com

2008-Nov-24 20:08 UTC

head link

[R] matching matrix columns to a vector

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!!
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide 
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.

Dan Davison

2008-Nov-24 20:15 UTC

head link

[R] matching matrix columns to a vector

Dan Davison wrote:> 
> 
> 
> Jagat.K.Sheth wrote:
>> 
>> How about which(colSums(t-v) == 0) ?
>> 
> 
> But what about v=c(2,1,3)? It needs to be something like
> 
> which(colSums((t - v)^2)) == 0
> or
> which(colSums(abs(t - v))) == 0
> Sorry, apparently I tried to write a line of R code without using emacs. Bad
idea. I meant
which(colSums((t - v)^2) == 0)
Dan

Dan Davison wrote:> 
> 
> Dan
> 
> 
> Jagat.K.Sheth wrote:
>> 
>> -----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!!
>> ______________________________________________
>> R-help at r-project.org mailing list
>> https://stat.ethz.ch/mailman/listinfo/r-help
>> PLEASE do read the posting guide
>> http://www.R-project.org/posting-guide.html
>> and provide commented, minimal, self-contained, reproducible code.
>> 
>> ______________________________________________
>> R-help at r-project.org mailing list
>> https://stat.ethz.ch/mailman/listinfo/r-help
>> PLEASE do read the posting guide
>> http://www.R-project.org/posting-guide.html
>> and provide commented, minimal, self-contained, reproducible code.
>> 
>> 
> 
> 
-- 
View this message in context:
http://www.nabble.com/matching-matrix-columns-to-a-vector-tp20664376p20668878.html
Sent from the R help mailing list archive at Nabble.com.

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