R help - Feb 2006 - Need frequency distribution for x,y coordinates

Hi,

I have a set of data in x,y coordinates across the range of -5 to 5 in each 
dimension. I would like to obtain the frequency distribution of the 
different points, and then graph them so you can see which of the points are 
the most frequently occurring.

This would seem to be easy in Matlab, which has the hist3 command for doing 
frequency distributions/histograms in 3 dimensions. However, as far as I can 
tell, R does not have a hist3 command.

Is there any easy way to do this in R? I'm investigating whether matlab or R
is more suitable for our needs, but don't want to reject R due to my present
ignorance of its functions.

_________________________________________________________________
realestate.com.au: the biggest address in property   
http://ninemsn.realestate.com.au

Check out:

http://addictedtor.free.fr/graphiques/graphcode.php?graph=116

On 2/11/06, mark shanks <markshanks101 at hotmail.com>
wrote:
> Hi,
>
> I have a set of data in x,y coordinates across the range of -5 to 5 in each
> dimension. I would like to obtain the frequency distribution of the
> different points, and then graph them so you can see which of the points
are
> the most frequently occurring.
>
> This would seem to be easy in Matlab, which has the hist3 command for doing
> frequency distributions/histograms in 3 dimensions. However, as far as I
can
> tell, R does not have a hist3 command.
>
> Is there any easy way to do this in R? I'm investigating whether matlab
or R
> is more suitable for our needs, but don't want to reject R due to my
present
> ignorance of its functions.
>
> _________________________________________________________________
> realestate.com.au: the biggest address in property
> http://ninemsn.realestate.com.au
>
> ______________________________________________
> R-help at stat.math.ethz.ch mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide!
http://www.R-project.org/posting-guide.html
>

On Sat, 11 Feb 2006, mark shanks wrote:
> Hi,
> 
> I have a set of data in x,y coordinates across the range of -5 to 5 in each
> dimension. I would like to obtain the frequency distribution of the 
> different points, and then graph them so you can see which of the points
are
> the most frequently occurring.
> 
> This would seem to be easy in Matlab, which has the hist3 command for doing
> frequency distributions/histograms in 3 dimensions. However, as far as I
can
> tell, R does not have a hist3 command.
See contributed package ash, function bin2:
> xy <- cbind(x=runif(250,-5,5), y=runif(250,-5,5))
> bins <- bin2(xy, ab=matrix(c(-5,-5,5,5),2,2))
> image(bins$nc)
or
> filled.contour(bins$nc)
Using the x and y arguments to image or filled.contour, you can set the 
axes, and asp=1 to preserve aspect.

See also function kde2d in package MASS - included in the standard 
distribution.

IMO, 3D histograms can mislead because perception depends on viewer 
position. All of the above give readily interpreted visualisations based 
on colour class intervals.
> 
> Is there any easy way to do this in R? I'm investigating whether matlab
or R
> is more suitable for our needs, but don't want to reject R due to my
present
> ignorance of its functions.
> 
> _________________________________________________________________
> realestate.com.au: the biggest address in property   
> http://ninemsn.realestate.com.au
> 
> ______________________________________________
> R-help at stat.math.ethz.ch mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide!
http://www.R-project.org/posting-guide.html
> 
-- 
Roger Bivand
Economic Geography Section, Department of Economics, Norwegian School of
Economics and Business Administration, Helleveien 30, N-5045 Bergen,
Norway. voice: +47 55 95 93 55; fax +47 55 95 95 43
e-mail: Roger.Bivand at nhh.no

Le Sat, 11 Feb 2006 04:40:41 -0500, Gabor Grothendieck a
??crit??:
> http://addictedtor.free.fr/graphiques/graphcode.php?graph=116
Or hist2d, in the gplots package :
http://addictedtor.free.fr/graphiques/RGraphGallery.php?graph=70

-- 
NoJhan

mark shanks wrote:
 >
 > Hi,
 >
 > I have a set of data in x,y coordinates across the range of -5 to 5 
in each
 > dimension. I would like to obtain the frequency distribution of the
 > different points, and then graph them so you can see which of the 
points are
 > the most frequently occurring.
 >
 > This would seem to be easy in Matlab, which has the hist3 command for 
doing
 > frequency distributions/histograms in 3 dimensions. However, as far 
as I can
 > tell, R does not have a hist3 command.

If a 2D display is okay, you can use the color2D.matplot function in the 
plotrix package to plot the output of something like kde2d in MASS:

x<-seq(-5,5,by=0.1)
xdens<-kde2d(sample(x,500,TRUE),sample(x,500,TRUE),n=11)
color2D.matplot(xdens$z,c(1,0),c(0,1),c(0,0),
show.legend=TRUE,xlab="Columns",ylab="Rows")

Jim