[R] plotting Formulas with greek letters and variable values (expression, substitute, paste, ...)

[rrookie1982]

rrookie1982 wrote:
> 
> I want to write a formula of the type
> 
>  http://n4.nabble.com/file/n1016112/expression.gif 
> 
> into my plot, where the values 1.234 and -0.567 should origin from
> variables in the program.
> 


Uwe Ligges-3 wrote:
> 
> It is much easier, just write the formula down in R syntax and 
> substitute the relevant variables as in:
> 
> text(0, 7.5, substitute(tau(A) == a*lg(A^b), list(a=1.234, b=-0.567)))
> 


Gabor Grothendieck wrote:
> 
> Try bquote:
> 
> a <- 0.1; b <- 0.2
> plot(0, main = bquote(tau(A) == .(a)*lg(A^.(b))))
> 

Wow, those two examples are indeed much simpler than my tries and work just
fine. Now I just will have two choose which way to go:

> suba <- 1.234; subb <- -0.567
> text(0, 5,substitute(tau(A) == a*lg(A^b), list(a=suba, b=subb)),pos=4)  ##
> and
> text(0, 5,bquote(tau(A) == .(suba)*lg(A^.(subb))),pos=4)

both work exactly how I wanted them to do.
Thank you Uwe and Gabor

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