On Jan 26, 2011, at 2:47 AM, Alaios wrote:
The reason is the following image
http://img545.imageshack.us/i/maptoregion.jpg/
In the picture above you will find the indexes for each cell.
Also you will see that I place that matrix inside a x,y region that
spans from -1 to 1. I am trying to write one function that will get
as argument a (x,y) value x e[-1,1] y e[-1,1] and will return the
indexes of that cell tha x,y value correspond to.
I really do not have a clue how I should try to approach that to
solve it. So based on some version I had for 1-d vector I tried to
extend it for 2-d. I used findInterval as a core to get results.
Unfortunately my code fails to produce accurate results as my
approach 'assumes' (this is something inhereted by the find Interval
function) that the numbering starts bottom left and goes high top
right.
You will find my code below
If one wants to take an ordinary r matrix and reorder it in the manner
you describe:
mtx2 <- mtx[ nrow(mtx):1, ]
Whether that is an efficient way to get at the sokution your you
programming task I cannot say. It sounds as though it has gotten too
convoluted. I was not able to comprehend the overall goal from your
problem description.
sr.map <- function(sr){
# This function converts the s(x,y) matrix into a function x that
spans #from -1 to 1 and y spans from -1 to 1.
# Input: sr a x,y matrix containing the shadowing values of a Region
breaksX <- seq(from=-1, to = 1, length = nrow(sr) +1L )
breaksY <- seq(from=-1, to = 1, length = ncol(sr) + 1L)
function(x,y){ # SPAGGETI CODE FOR EVER
indx <- findInterval(x, breaksX,rightmost.closed=TRUE)
indy <- findInterval(y, breaksY,rightmost.closed=TRUE)
c(indx,indy)
}
}
sr<-matrix(data=seq(from=1,to=36),nrow=6,ncol=6,byrow=TRUE)
f.sr.map<-sr.map((sr))
f.sr.map(-0.1,-0.1)
f.sr.map(0.1,0.1)
Best Regards
Alex
--- On Wed, 1/26/11, David Winsemius <dwinsem...@comcast.net> wrote:
From: David Winsemius <dwinsem...@comcast.net>
Subject: Re: [R] MAtrix addressing
To: "Alaios" <ala...@yahoo.com>
Cc: R-help@r-project.org
Date: Wednesday, January 26, 2011, 2:54 AM
On Jan 25, 2011, at 4:50 PM, Alaios wrote:
Hello
I would like to ask you if it is possible In R Cran to
change the default way of addressing a matrix.
for example
matrix(data=seq(from=1,to=4,nrow=2,ncol=2, by row
numbering) # not having R at this pc
will create something like the following
1 2
3 4
the way R address this matrix is from top left corner
moving to bottom right.
The cell numbers in that way are
1 2
3 4
IS it possible to change this default addresing number
to something that goes bottom left to top right? In this
simple case I want to have
3 4
1 2
Would that be possible?
Yes. it's possible but ... why?
I would like to thank y for your help
Regards
Alex
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David Winsemius, MD
West Hartford, CT
David Winsemius, MD
West Hartford, CT
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and provide commented, minimal, self-contained, reproducible code.
