Math expression with object to evaluate

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You might want to read the "R Help Desk: Automation of Mathematical 
Annotation in Plots" in R News 2 (3), 32-34.
and you will understand that the following works:

plot(x, y, main =
   substitute("ID is" * ID.i * ", " * italic(R)^2 ==
               r2.i * {", RMSE" == error.i},
              list(ID.i = ID.i, r2.i = r2.i, error.i = error.i)))

For the next time, please make your example reproducible as the posting 
guide asks you to do.

Uwe Ligges
Hello.

I have a question that probably has a simple answer.

I have a loop where several figures are plotted with each iteration. I calculate some descriptives to put in the title of the figure. When I use expression, since I want to combine math plotting symbols and the descriptives I calculate, I get an error. Here is an example of the code that I tried:

plot(x,y, main=expression(paste("ID is", ID.i, italic(R)^2, r2.i, "RMSE", error.i)))

where ID.i, r2.i, and error.i change for each iteration of the loop. I suppose the problem is that expression does not know to treat each of these as objects rather than part of a mathematical expression. Is there a way to display the value of ID.i, r2.i, and error.i within the expression? 

Thanks for any thoughts,
Ken

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______________________________________________
R-help at stat.math.ethz.ch mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
Use bquote:

ID <- 3
plot(1,1, main = bquote(ID ~ is ~ .(ID)))

Also please read the last line of every message to r-help regarding
reproducible examples.  (None of your variables were defined.)
Hello.

I have a question that probably has a simple answer.

I have a loop where several figures are plotted with each iteration. I calculate some descriptives to put in the title of the figure. When I use expression, since I want to combine math plotting symbols and the descriptives I calculate, I get an error. Here is an example of the code that I tried:

plot(x,y, main=expression(paste("ID is", ID.i, italic(R)^2, r2.i, "RMSE", error.i)))

where ID.i, r2.i, and error.i change for each iteration of the loop. I suppose the problem is that expression does not know to treat each of these as objects rather than part of a mathematical expression. Is there a way to display the value of ID.i, r2.i, and error.i within the expression?

Thanks for any thoughts,
Ken

 __________________________________________________

       [[alternative HTML version deleted]]

______________________________________________
R-help at stat.math.ethz.ch mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.