R version 2.15.3 (2013-03-01) -- "Security Blanket"
Copyright (C) 2013 The R Foundation for Statistical Computing
ISBN 3-900051-07-0
Platform: i686-pc-linux-gnu (32-bit)

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> x <- array(list("f",-2.67,"f",9.67,"f",-6.00,"f",28.33,"f",12.00,"f",-11.30,"f",3.00,"f",-4.67,"f",-5.00,"f",2.33,"f",37.67,"f",7.50,"f",5.00,"f",30.00,"f",15.33,"m",-6.50,"m",-7.33,"m",49.33,"m",-11.00,"m",-8.33,"m",9.00,"m",2.33,"m",-12.30,"m",5.67,"m",-2.00,"m",1.33,"m",-13.00,"m",-5.67,"m",-4.00,"m",2.00),dim=c(2,30),dimnames=list(c('PMent','Exam'),1:30))
>  y <- array(NA,dim=c(2,30),dimnames=list(c('PMent','Exam'),1:30))
>  for (i in 1:dim(x)[1])
+  {
+  	for (j in 1:dim(x)[2])
+  	{
+  		y[i,j] <- as.numeric(x[i,j])
+  	}
+  }
There were 30 warnings (use warnings() to see them)
> par5 = '2'
> par4 = '1'
> par3 = '0'
> par2 = 'TRUE'
> par1 = 'grey'
> ylab = 'Degree Grade'
> xlab = 'Placement Student'
> main = 'Reddy-Moores Placement Data'
> par5 <- '2'
> par4 <- '1'
> par3 <- '0'
> par2 <- 'TRUE'
> par1 <- 'grey'
> #'GNU S' R Code compiled by R2WASP v. 1.2.291 ()
> #Author: aston2
> #To cite this work: Ian E. Holliday, 2012, Histogram and QQplot (v1.0.6) in Free Statistics Software (v$_version), Office for Research Development and Education, URL http://www.wessa.net/Ian.Holliday/rwasp_Reddy-Moores%20Data%20Boxplot.wasp/
> #Source of accompanying publication: 
> #
> postscript(file="/var/fisher/rcomp/tmp/1iihf1369233248.ps",horizontal=F,onefile=F,pagecentre=F,paper="special",width=8.3333333333333,height=5.5555555555556) 
> par2<- as.logical(par2) # notches
> par3<-as.numeric(par3) # percentage trim
> if(par3>45){par3<-45;warning('trim limited to 45%')}
> if(par3<0){par3<-0;warning('negative trim makes no sense. Trim is zero.')}
> par4 <- as.numeric(par4) #factor column
> par5 <- as.numeric(par5) # response column
> x <- t(x)
> x1<-as.numeric(x[,par5]) # response
> f1<-as.character(x[,par4]) # factor
> x2<-x1[f1=='no']
> f2 <- f1[f1=='no']
> lotrm<-as.integer(length(x2)*par3/100)
> hitrm<-as.integer(length(x2)*(100-par3)/100)
> srt<-order(x2,f2)
> trmx1<-x2[srt[lotrm:hitrm]]
> trmf1<-f2[srt[lotrm:hitrm]]
> x3<-x1[f1=='yes']
> f3 <- f1[f1=='yes']
> lotrm<-as.integer(length(x3)*par3/100)
> hitrm<-as.integer(length(x3)*(100-par3)/100)
> srt<-order(x3,f3)
> trmx2<-x3[srt[lotrm:hitrm]]
> trmf2<-f3[srt[lotrm:hitrm]]
> xtrm<-c(trmx1,trmx2)
> ftrm<-c(trmf1,trmf2)
> xtrm[1:6]
[1] NA NA NA NA NA NA
> ftrm[1:6]
[1] NA NA NA NA NA NA
> r<-boxplot(xtrm~as.factor(ftrm), col=par1, notch=par2, main=main, xlab=xlab, ylab=ylab)
Error in boxplot.default(split(mf[[response]], mf[-response]), ...) : 
  invalid first argument
Calls: boxplot -> boxplot.formula -> boxplot -> boxplot.default
In addition: Warning message:
In is.na(rows) : is.na() applied to non-(list or vector) of type 'NULL'
Execution halted