R help - Jan 2008 - "non-plot" plotting

I really do not know ho to else title this ... I want to draw something like
the attached png with R and would like to poll you on how to start ... make
an empty plot first and then start positioning the characterstring
by 'text' and then drawing the lines ...

Joh
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On Jan 17, 2008, at 9:44 AM, Johannes Graumann wrote:
> I really do not know ho to else title this ... I want to draw  
> something like
> the attached png with R and would like to poll you on how to  
> start ... make
> an empty plot first and then start positioning the characterstring
> by 'text' and then drawing the lines ...
That sound about right. I would probably do some computations first  
to determine how much space I would need etc. A key thing I think  
would be to choose a good coordinate system, that would make placing  
the text and lines easier. I would also probably write minifunctions,  
that place a whole "y plus its lines" etc.

Now, if you want kerning on the letters, that probably gets trickier.  
But as long as you are willing to assume a fixed horizontal space for  
each letter, I see no problems. (In your case, for instance, I would  
probably choose the x dimensions to go from 0 to 13, and place the  
letters each at the coordinates 1 through 12, centered).
> Joh
> <sequence.png>
>
Haris Skiadas
Department of Mathematics and Computer Science
Hanover College

Johannes Graumann wrote:
> I really do not know ho to else title this ... I want to draw something
like
> the attached png with R and would like to poll you on how to start ... make
> an empty plot first and then start positioning the characterstring
> by 'text' and then drawing the lines ...
>
> Joh
Johannes,

Try this (PDF of the output attached):

# Open the initial plot window and set
# up a coordinate system based upon
# placement of the letters centered
# on integer 'x' values 1:12
plot(1, xlim = c(0, 13), ylim = c(0, 4),
      type = "n",
      ann = FALSE, axes = FALSE)

# Create the vector of letters
Vec <- c("T", "V", "F", "S",
"Q", "A", "Q",
          "L", "C", "A", "L",
"K")

# Plot them
text(1:12, 2, Vec, cex = 2, font = 2)

# Get the height of the letters for spacing
# See ?strheight
height <- strheight("T", cex = 2) * .8

# Set a default width for the "boxes"
# around the letter
width <- 0.5

# Set the values for 'Y's
Y <- 10:2
X <- 3:11

# Loop over the Y's and using plotmath
# plot the values and subscripts in bold
# See ?plotmath and ?bquote
# While looping, do the colored segments
for (i in 1:9) {
   text(X[i], 2 + (height * 1.6), bquote(bold(Y[.(Y[i])])),
        col = "red", font = 2)

   x <- c(X[i] - width, X[i] - width, X[i] + 0.3)
   y <- c(2, 2 + height, 2 + height)

   lines(x, y, col = "red", lwd = 2)
}




# Same here now for the 'b's

b <- c(2:6, 8, 9, 11)
X <- b

for (i in 1:8) {
   text(X[i], 2 - (height * 1.6), bquote(bold(b[.(b[i])])),
        col = "blue", font = 2)

   x <- c(X[i] - 0.3, X[i] + width, X[i] + width)
   y <- c(2 - height, 2 - height, 2)

   lines(x, y, col = "blue", lwd = 2)
}



The above should provide the basic approach. You can then adjust/fine 
tune spacing, etc. as you require.

HTH,

Marc Schwartz

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