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do calculation within expression(), text in plot

2 messages · Tonja Krueger, William Dunlap

#
Dear Helpers,
   I would like to add some text to my plot, containing a variable and the
   calculated value for the variable.
   As  I  would  like  to  produce  many  plots,  I hope this can be done
   automatically.
   Unfortunately I can't get R to do the calculation for cor(nou,dak) when I
   use expression()..

   text(0,2.2,expression(paste(r[Pearson],"=", cor(nou,dak) , sep= " ")),pos=4,
   cex=1.5)

   Is there a command that "stops" expression() so the result is calculated and
   printed in the plot?
   Thank you in advance,
   Tonja
#
Use bquote() and its .() operator, as in
  with(mtcars, {
      plot(wt, mpg)
      text(4, 30, bquote(r[Pearson] ~ "=" ~ .(cor(wt, mpg))))
  })

Bill Dunlap
TIBCO Software
wdunlap tibco.com