[R] Display of 3d arrays

[Agustin Lobo]

Thanks Ben,

An improvement would be indexing the colors,
as often there will be fewer colors than cells.

For example:

tstarr <-
array(rep(c(0,0,0,0,200,200,200,200,250,250,250,250),12*3*3),dim=c(8,3,3))
colmat <- apply(tstarr/256,c(1,2),function(z)do.call("rgb",as.list(z)))
cols <- as.vector(unique(colmat))
                  ^^^^^^
and use (for this example):
cbind(c(rep(1,4),rep(2,4)),c(rep(3,4),rep(1,4)),c(rep(2,4),rep(3,4)))

in  image() instead of:
matrix(1:length(colmat),nrow=nrow(colmat))

The question now is to find a general way of selecting and 
indexing the unique triplets.

Agus

Dr. Agustin Lobo
Instituto de Ciencias de la Tierra (CSIC)
Lluis Sole Sabaris s/n
08028 Barcelona SPAIN
tel 34 93409 5410
fax 34 93411 0012
alobo at ija.csic.es


On Mon, 27 Aug 2001 ben at zoo.ufl.edu wrote:

> 
>   This isn't quite a perfect solution but you might be able to make it
> work:
> 
> ## data
> x <- c(170,174,173,172,161,
> 171,178,174,166,149,
> 168,174,173,166,156,
> 171,170,173,166,164,
> 167,170,170,171,169,
> 138,131,128,128,125,
> 138,127,129,122,134,
> 144,131,130,127,132,
> 142,138,130,131,129,
> 146,141,135,129,131,
> 124,123,127,125,125,
> 125,126,126,126,123,
> 127,123,125,128,128,
> 123,121,125,125,126)
> 
> ## reshape data to your specifications
> y <- array(x,dim=c(5,5,3))
> z <- aperm(y,c(2,1,3))
> 
> ## color matrix from array
> colmat <- apply(z/256,c(1,2),function(z)do.call("rgb",as.list(z)))
> 
> 
> ## hack -- fake image() into plotting specific colors
> cols <- as.vector(colmat)
> image(matrix(1:length(colmat),nrow=nrow(colmat)),col=cols)
> 
> ## test
> tstarr <- array(c(256,256,0,0,0,0,256,256,0,256,256,0),
>                 dim=c(2,2,3))
> tstarr
> colmat <- apply(tstarr/256,c(1,2),function(z)do.call("rgb",as.list(z)))
> cols <- as.vector(colmat)
> image(matrix(1:length(colmat),nrow=nrow(colmat)),col=cols)
> 
> 
> On Sun, 26 Aug 2001, Agustin Lobo wrote:
> 
> > Hi!
> >
> > Is it possible to display a 3d array as
> > an RGB image? For example, given the following
> > array:
> > > matriz3d
> > , , 1
> >
> >      [,1] [,2] [,3] [,4] [,5]
> > [1,]  170  174  173  172  161
> > [2,]  171  178  174  166  149
> > [3,]  168  174  173  166  156
> > [4,]  171  170  173  166  164
> > [5,]  167  170  170  171  169
> >
> > , , 2
> >
> >      [,1] [,2] [,3] [,4] [,5]
> > [1,]  138  131  128  128  125
> > [2,]  138  127  129  122  134
> > [3,]  144  131  130  127  132
> > [4,]  142  138  130  131  129
> > [5,]  146  141  135  129  131
> >
> > , , 3
> >
> >      [,1] [,2] [,3] [,4] [,5]
> > [1,]  124  123  127  125  125
> > [2,]  125  126  126  126  123
> > [3,]  127  123  125  128  128
> > [4,]  123  121  125  125  126
> > [5,]  118  122  124  126  125
> >
> > the first row would be diplayed with rgb colors matriz3d[1,1:5,]
> >
> > (170 138 124) (174 131 123) (173 128 127) (172 128 125) (161 125 125)
> >
> >
> > Thanks
> >
> > Agus
> >
> > Dr. Agustin Lobo
> > Instituto de Ciencias de la Tierra (CSIC)
> > Lluis Sole Sabaris s/n
> > 08028 Barcelona SPAIN
> > tel 34 93409 5410
> > fax 34 93411 0012
> > alobo at ija.csic.es
> >
> >
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> 
> -- 
> 318 Carr Hall                                bolker at zoo.ufl.edu
> Zoology Department, University of Florida    http://www.zoo.ufl.edu/bolker
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> 

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