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, 12:49 PM
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
