[R] ggplot2 help/suggestions needed

ONKELINX, Thierry Thierry.ONKELINX at inbo.be
Fri Jul 29 10:56:24 CEST 2011

Dear Bruce,

It's doable with ggplot2, but image() is probably a better solution.

To use ggplot2, you will need to convert your array into a data.frame where each row has the information for one cell (x, y and colour)

#create some dummy data
dataset <- expand.grid(x = seq_len(10), y = seq_len(10))
dataset$r <- rescale(dataset$x)
dataset$g <- rescale(dataset$y)
dataset$b <- rescale(dataset$x - dataset$y)

#create the colour information
dataset$colour <- with(dataset, rgb(r, g, b))
dataset$fColour <- factor(dataset$colour)

#the plot
ggplot(dataset, aes(x = x, y = y, fill = fColour)) + geom_tile() + scale_fill_manual(values = levels(dataset$fColour))

Best regards,


ir. Thierry Onkelinx
Instituut voor natuur- en bosonderzoek
team Biometrie & Kwaliteitszorg
Gaverstraat 4
9500 Geraardsbergen

Research Institute for Nature and Forest
team Biometrics & Quality Assurance
Gaverstraat 4
9500 Geraardsbergen

tel. + 32 54/436 185
Thierry.Onkelinx op inbo.be

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~ Sir Ronald Aylmer Fisher

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~ Roger Brinner

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> -----Oorspronkelijk bericht-----
> Van: r-help-bounces op r-project.org [mailto:r-help-bounces op r-project.org]
> Namens Bruce Rex
> Verzonden: donderdag 28 juli 2011 20:42
> Aan: r-help op r-project.org
> Onderwerp: [R] ggplot2 help/suggestions needed
> Hello,
> I have written a version of the Kohenen Self Organizing Map (in R) and wish to
> use ggplot2 for the visualization. My results are RGB values in a matrix [x,y,1:3]
> where x and y comprise the first two dimensions and the third dimension is the
> RGB vector.
> I am not sure whether to use geom_tile or geom_hex as there really is no
> binning at the finest granularity. For testing, the matrix is 100, 100, 3 in size.
> What approach would you suggest?
> TIA,
> DrX
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