[R] legend(1,1,expression(a<-"10^-6"))

[Uwe Ligges]

Viet Nguyen wrote:

> hi all,
> 
> I have a problem with showing properly formated mathematical expressions 
> in a plot.
> 
> The following works:
> 
> plot(1:10)
> legend(1,10, expression(10^-6))
> 
> Howver, if my expression is kept in a char variable, I don't know how to 
> show it in the legend.
> 
> # I have
> st_"10^-6"

You have got a completely outdated version of R, if the code given above 
really works. Note that _ has long been depeceated and does no longer 
work for assignments.


> # I try to do this
> plot(1:10)
> legend(1,10, expression(st))
> # which doesn't turn out as expected
> 

?parse: "parse returns the parsed but unevaluated expressions in a list. 
Each element of the list is of mode expression."

  st <- "10^{-6}"
  plot(1:10)
  legend(1,10, parse(text = st))

Uwe Ligges



> Is it possible to convert a string into expression? Or is there a 
> different way of doing what I want to do?
> 
> Thanks in advance for your help.
> viet
> 
> ______________________________________________
> R-help at stat.math.ethz.ch mailing list
> https://www.stat.math.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide! 
> http://www.R-project.org/posting-guide.html