expression

Mathematical expressions in R plot

Mathematical anotations to R plots can be formated LaTeX style with the expression function. The expression() can be included in

  • plot titles 
    title( expression(...))
  • axis anotations 
    plot( ... , xlab = expression(...))

    or

  • the plot panel itself 
    text( x , y , expression(...))

An example:

plot( 0 , 0 , type = "n" , xlab = expression( "Nothing" * (mu*mol/l)) )
text( 0 , 0 , expression(beta>=0.2))
title( expression( "Only an expression() demo " * theta^(2*pi)))

It is even possible to update the plot anotation from a variable (found on the R forum)

[R] Expression in plot text

Roger Koenker roger at ysidro.econ.uiuc.edu
Wed Dec 6 20:22:05 CET 2000 

expression(paste(hat(theta),'= ',that)))

We’ve been here before. To get an expression either use parse on your
pasted character string or substitute on an expression. There are worked
examples in the list achives. The neatest is

title(substitute(hat(theta) == that, list(that=that)))

(note it is == not =)

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