R help - Oct 2005 - greek symbols using pch

Hi R-users,

    In a plot, can I specify pch to be a greek symbol? (I looked at
show.pch() in the Hmisc package but couldn't see the right symbols in
there).
If not, I guess I can get around this using text(x,y,expression()).

cheers!,

Matt.


Dr Matt Fischer
Postdoctoral Fellow - IPILPS
ANSTO - Institute for Nuclear Geophysiology 
Building 21A
PMB 1 Menai NSW 2234
Ph: +61 2 9717 9686
Fax: +61 2 9717 3599
Mobile: 0428 363 146
http://www.ansto.gov.au/nugeo/
http://ipilps.ansto.gov.au/



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On Mon, 2005-10-10 at 12:02 +1000, FISCHER, Matthew
wrote:
> 
> Hi R-users,
> 
>     In a plot, can I specify pch to be a greek symbol? (I looked at
> show.pch() in the Hmisc package but couldn't see the right symbols in
there).
> If not, I guess I can get around this using text(x,y,expression()).
> 
> cheers!,
> 
> Matt.

You will need to use text() in order to plot greek characters as
plotting symbols.

The 'pch' argument (or par("pch")) must be a single character
or an
integer specifying one of the symbols as seen in ?points or as you noted
in Frank's show.pch().

See ?plotmath for more information on plotting mathematical expressions.

HTH,

Marc Schwartz

"FISCHER, Matthew" <mjf at ansto.gov.au> wrote in message
news:283982AD9F3CD211B3AC00A0C983032F11443674 at paradise.ansto.gov.au...
>     In a plot, can I specify pch to be a greek symbol? (I looked at
> show.pch() in the Hmisc package but couldn't see the right symbols in
there).
> If not, I guess I can get around this using text(x,y,expression()).
I'm not sure where this is explained very well.  Having ?font give a clue
about this would be nice.

Use font=5, the symbol font.  To see what's in font=5:

par(font=5, las=1)
plot(0:15,0:15,type="n",ylim=c(15,0),
  main="Symbols in Font=5",
  xlab="", ylab="",xaxt="n", yaxt="n")
axis(BOTTOM<-1, at=0:15, 1:16)
axis(LEFT  <-2, at=0:15)
abline(v=0.5 + 0:14,
       h=0.5 + 0:14, col="grey", lty="dotted")

# pch index of any cell is 16*row + column
for(i in 0:255)
{
  x <- i %%16;
  y <- i %/% 16;
  points(x,y,pch=i+1)
}

The Greek letters are from 65 to 90 and 97 to 122 in this font.

Here are random points with Greek letters as the plot character:

par(font=5)
# Use Greek letter for plot characters from font=5
plot(0:1, 0:1, axes=F, type="n", xlab="", ylab="",
  main="Greek plotting characters")
box()
points(runif(100), runif(100), pch=c(65:90, 97:122))

--
efg
Earl F. Glynn
Scientific Programmer
Stowers Institute for Medical Research