[R] Legend text populated with calculated values and super script?

[David Winsemius]

On Feb 7, 2014, at 7:54 AM, Douglas M. Hultstrand wrote:

> Hello,
> 
> I am trying to generate a plot legend that contains calculated summary 
> statistics, one statistic is R^2.  I have tried several variations using 
> the commands "expression" and "bqoute" as stated on the R help pages.  I 
> have not been able to get the R^2 super script correct along with the 
> calculated statistics.
> 
> I provided an example below, what I want is the legend (wdt_leg and 
> spas_leg) as below but with the R^2 as superscript.
> 
> # Example Data
> x=c(1,2,3,4);  y=c(1,2,3,4); z=c(1.25,1.5,2.5,3.5)
> 
> # first stats based on data, used to populate legend
> wdt_n = 50;  wdt_mbias = 0.58
> wdt_mae = 2.1;  wdt_R2 = 0.85
> # second stats based on data, used to populate legend
> spas_n = 50; spas_mbias = 0.58
> spas_mae = 2.1; spas_R2 = 0.85
> 
> # create legend
> wdt_leg <- paste("WDT (N = ", wdt_n,", Bias = ",wdt_mbias,", MAE = 
> ",wdt_mae, ", R2 = ", wdt_R2, ")", sep="")
> spas_leg <- paste("SPAS (N = ", spas_n,", Bias = ",spas_mbias,", MAE = 
> ",spas_mae, ", R2 = ", spas_R2, ")", sep="")
> 
> # create plot
> plot(x,y, col="red1", pch=1); lines(x,z, type="p", col="green4",pch=3)
> leg.txt <- c(spas_leg, wdt_leg)
> legend("topleft", legend = leg.txt, col=c("red1","green4"), pch=c(1,3), 
> cex=0.85)

sublist <- 
structure(list(wdt_n = 50, wdt_mbias = 0.58, wdt_mae = 2.1, wdt_R2 = 0.85, 
    spas_n = 50, spas_mbias = 0.58, spas_mae = 2.1, spas_R2 = 0.85), .Names = c("wdt_n", 
"wdt_mbias", "wdt_mae", "wdt_R2", "spas_n", "spas_mbias", "spas_mae", 
"spas_R2"))

legends <-c( 
  substitute( 
    atop(WDT * group("(", list(N == wdt_n, Bias == wdt_mbias, MAE == wdt_mae ), ")" ),
      R^2 == wdt_R2 ) ,  env=sublist), 
  substitute(   
    atop(SPAS * group("(", list(N == spas_n, Bias == spas_mbias, MAE == spas_mae ), ")"),
      R^2 == spas_R2 ), env=sublist)  )

# I tried with: as.expression( lapply( exprlist, function(e) bquote(e) ) ) but failed repeatedly.
# In order to get `substitute` to cook the bacon, you need to use real expressions, not text.

plot(x,y, col="red1", pch=1); lines(x,z, type="p", col="green4",pch=3)
legend("topleft", 
   legend = as.expression(legends), 
   col=c("red1","green4"), pch=c(1,3), 
   cex=0.85)


-- 
David Winsemius
Alameda, CA, USA