Re: [R] From two colors to 01 sequences

2009-05-12 Thread Zeljko Vrba 
On Tue, May 12, 2009 at 12:20:56PM +0100, Paul Smith 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?
 
I would not do it with R, but.. here's the general approach:

  1. Convert the PDF to some raster format at high enough resolution (DPI)
 without any kind of compression or anti-aliasing
  2. Use some image manipulation program to replace red/green with black/white
  3. Save the resulting picture in ASCII PBM format
  4. Parse the resulting PBM and find 0-1 and 1-0 transitions which will give
 you rectangle boundaries.
  5. You did not specify the kind of rectangles, nor whether rows are of
 uniform height, so I assume uniform grid.  Otherwise, position and size
 might also be relevant[1], the interpretation is completely up to you.

[1] As in, for example, http://educ.queensu.ca/~fmc/october2001/GoldenArt3.gif
(Imagine that there are only two colors instead of 4 + black lines)

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Re: [R] From two colors to 01 sequences

2009-05-12 Thread baptiste auguie 

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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Re: [R] From two colors to 01 sequences

2009-05-12 Thread Paul Smith 
Thanks, Baptiste and Zeljko. I am attaching here an example of the
picture of the rectangles.

Paul


On Tue, May 12, 2009 at 1:23 PM, baptiste auguie ba...@exeter.ac.uk wrote:

 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
 __


        [[alternative HTML version deleted]]


 __
 R-help@r-project.org mailing list
 https://stat.ethz.ch/mailman/listinfo/r-help
 PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
 and provide commented, minimal, self-contained, reproducible code.


__
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.