[R] identify extremes positions of values into matrix

[Francisco Zagmutt]

I am glad to help ;-)

Cheers,

Francisco



Milton Cezar Ribeiro wrote:
> Francisco, 
>   Thank you so much. It´s more than I need. 
>   You help was of great value.
>    
>   Kind regards,
>    
>   Miltinho
> 
> "Francisco J. Zagmutt" <gerifalte28 at hotmail.com> escreveu:
>   Oi Milton,
> 
> Is this what you are after?
> 
> x=read.table("miltondat.txt")
>> x
> V1 V2 V3 V4 V5 V6 V7 V8 V9 V10
> 1 0 0 0 0 0 0 0 0 0 0
> 2 0 0 0 0 0 1 1 1 0 0
> 3 0 0 0 0 0 1 1 1 0 0
> 4 0 0 0 0 0 0 0 0 0 0
> 5 0 0 2 2 2 0 0 0 0 0
> 6 0 0 0 2 2 2 0 0 0 0
> 7 0 0 2 2 2 2 2 2 0 0
> 8 0 0 0 0 0 0 0 0 0 0
> 
> idx=which(x==2,arr.ind=T) #Index of observations with values == 2 . Notice 
> the use of arr.ind=t to get the rows and columns of the observations
> 
>> idx
> row col
> 5 5 3
> 7 7 3
> 5 5 4
> 6 6 4
> 7 7 4
> 5 5 5
> 6 6 5
> 7 7 5
> 6 6 6
> 7 7 6
> 7 7 7
> 7 7 8
> 
>> range(idx[,"row"]) #gives you the min and max of the rows with x==2
> [1] 5 7
>> range(idx[,"col"])#gives you the min and max of the columns with x==2
> [1] 3 8
> 
> 
> You can refine this and wrap it in a function to make reports in a more 
> suitable form
> 
> Regards
> 
> Francisco
> 
> Dr. Francisco J. Zagmutt
> College of Veterinary Medicine and Biomedical Sciences
> Colorado State University
> 
> 
> 
> 
>> From: Milton Cezar Ribeiro 
>> To: r-help at stat.math.ethz.ch
>> Subject: [R] identify extremes positions of values into matrix
>> Date: Fri, 3 Nov 2006 11:25:32 -0300 (ART)
>>
>> Hi R-friends around world!
>> I have a matrix that looks like bellow one.
>> Each cell are filled with values 0, 1 or 2.
>> In fact I have a lot of 512x512 matrices, with
>> values varying from 0 to 999.
>> I need to retrieve the left and right columns
>> and the top and botton lines of the matrix
>> where occours for example the value 2.
>> Column and row labels are included at the example.
>>
>> 1234567890
>> 1 0000000000
>> 2 0000011100
>> 3 0000011100
>> 4 0000000000
>> 5 0022200000
>> 6 0002220000
>> 7 0022222200
>> 8 0000000000
>>
>> At this example, the right answer are:
>> collumns 3 and 8
>> lines 5 and 7
>> Any idea of how can I solve this?
>> Kind regards,
>> Miltinho
>>
>>
>> ---------------------------------
>>
>> Música para ver e ouvir: You're Beautiful, do James Blunt
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>>
> 
> 
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> 
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