
Depending on the nature of your pdf file, it may be possible to use  
the grImport package. I've never used it before, but a quick test  
seems promising,

>  # create a test picture
> colorStrip <-
> function (colors, draw = T)
> {
>     x <- seq(0, 1 - 1/ncol(colors), length = ncol(colors))
>     y <- rep(0.5, length(colors))
>     my.grob <- grid.rect(x = unit(x, "npc"), y = unit(y, "npc"),
>         width = unit(1/ncol(colors), "npc"), height = unit(1,
>             "npc"), just = "left", hjust = NULL, vjust = NULL,
>         default.units = "npc", name = NULL, gp = gpar(fill =  
> rgb(colors[1,
>             ], colors[2, ], colors[3, ]), col = rgb(colors[1,
>             ], colors[2, ], colors[3, ])), draw = draw, vp = NULL)
>     my.grob
> }
>
>
> colors <- rbind(c(1, 0, 1), c(0, 1, 0), c(0, 0, 0))
>
> pdf("testRGB.pdf")
> colorStrip(colors)
> dev.off()
>
>
> # import the pdf file into R
> library(grImport)
> PostScriptTrace("testRGB.pdf")
>
> test <- readLines("testRGB.pdf.xml")
>
> testRead <- readPicture("testRGB.pdf.xml")
>
> str(testRead)
> grid.picture(testRead) # somehow I've lost the fill color in the  
> process?!
>
> grep("<rgb.+", test, value=T) # this should allow you to find the  
> sequence of red and green rectangles

HTH,

baptiste




On 12 May 2009, at 13:38, Zeljko Vrba wrote:
>>
>> I have got several pdf files with rows of colored rectangles: red
>> rectangles should be read as 0; green rectangles as 1. No other color
>> exists. Is there some way to have R reading the colored rectangles to
>> a matrix or data frame converting the color of the rectangles to
>> sequences of 01?
>>

_____________________________

Baptiste Auguié

School of Physics
University of Exeter
Stocker Road,
Exeter, Devon,
EX4 4QL, UK

Phone: +44 1392 264187

http://newton.ex.ac.uk/research/emag
______________________________


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