[R] question how to add Standard Deviation as "Whiskers" in a simple plot

[David Winsemius]

On May 28, 2012, at 9:55 AM, gianni lavaredo wrote:

> Dear Researchers,
>
> sorry for this simple question. I  have a point plot with mean  
> values and i
> wish to plot line with Standard Deviation as "Whiskers". I calculate  
> the
> mean+sd and mean-sd, but i can not figure out the way to add the line.
>
> mydata <-
> data 
> .frame 
> (mean 
> = 
> c 
> (0.42,0.41,0.41,0.43,0.45,0.43,0.43,0.42,0.44,0.45,0.45,0.45,0.46,0.43,0.42,0.37,0.44,0.46,0.46,0.39,0.40 
> ),
>
> sdUP 
> = 
> c 
> (0.58,0.56,0.55,0.57,0.61,0.55,0.57,0.59,0.61,0.60,0.57,0.60,0.62,0.57,0.59,0.56,0.57,0.61,0.61,0.56,0.54 
> ),
>
> sdDOWN 
> = 
> c 
> (0.26,0.26,0.28,0.29,0.30,0.30,0.29,0.26,0.28,0.31,0.34,0.30,0.31,0.30,0.25,0.19,0.31,0.31,0.31,0.22,0.25 
> ))
>
> plot(mydata$mean,
>    type="o",
>    ylab="mean",
>    xlab="class")
>
> thanks in advance and sorry for any disturb

If you tried lines() usin either sdUP or sdDOWN you saw nothing  
because the ylim was set by default using ony hte information in the  
mean vector.

Try:

 > plot(mydata$mean,
+    type="o",
+    ylab="mean",
+    xlab="class", ylim=range(c(mydata$sdUP, mydata$sdDOWN)))
 > lines(mydata$sdDOWN, col="blue", lty=3)
 > lines(mydata$sdUP, col="blue", lty=3)


-- 
David.