[R-sig-teaching] adding plus/minus 1 standard devaition into eachbar in cluster bar chart

[William Revelle]

Another error.bars function is found in the psych package.

For zanaty's data, a log transform makes more sense:

package(psych)
error.bars.by(my.data$data,my.data$cat2,by.var=TRUE,bars=TRUE,sd=TRUE) 
#original data
error.bars.by(log(my.data$data),my.data$cat2,by.var=TRUE,bars=TRUE,sd=TRUE) 
#log transformed data
error.bars.by(log(my.data$data),my.data$cat1*(my.data$cat2+3),by.var=TRUE,bars=TRUE,sd=TRUE) 
#to group by cat1 and cat2
?error.bars.by


Bill



At 10:20 AM +0100 12/13/10, Adams, Zeno wrote:
>In Michael Crawley's "The R Book" (which I can highly recommend for 
>teaching undergraduate statistics) the author proposes a function 
>that adds the standard errors with the line function. The function 
>has three arguments: The means, the standard errors, and the bar 
>labels. For a reproducible dataset such as:
>
>dat1 <- data.frame(income = c((2000 + 500*rnorm(10)),(2500 + 
>500*rnorm(10))), gender = rep(c("m","f"),c(10,10)))
>
>with
>
>ybar <- tapply(dat1$income, dat1$gender, mean)
>se <- tapply(dat1$income, dat1$gender, sd)/10
>labels <- as.character(levels(dat1$gender))
>
>as the means, se, and labels, respectively
>
>the function is:
>
>error.bars<-function(yv,z,nn) {
>xv<-
>barplot(yv,ylim=c(0,(max(yv)+max(z))),names=nn,ylab=deparse(substitute(yv)
>))
>g=(max(xv)-min(xv))/50
>for (i in 1:length(xv)) {
>lines(c(xv[i],xv[i]),c(yv[i]+z[i],yv[i]-z[i]))
>lines(c(xv[i]-g,xv[i]+g),c(yv[i]+z[i], yv[i]+z[i]))
>lines(c(xv[i]-g,xv[i]+g),c(yv[i]-z[i], yv[i]-z[i]))
>}}
>
>which can be used after plotting the data:
>
>barplot(ybar)
>error.bars(ybar, se, labels)
>
>
>Zeno
>
>
>-----Original Message-----
>From: r-sig-teaching-bounces at r-project.org on behalf of Ali Zanaty
>Sent: Sat 12/11/2010 3:43 PM
>To: r-sig-teaching at r-project.org
>Subject: [R-sig-teaching] adding plus/minus 1 standard devaition 
>into eachbar in cluster bar chart
>
>Dear All R users:
>
>I hope that this message finds all of you well.
>
>Currently, I am teaching an undergraduate course in statistics.
>
>If possible, Could you please help me out how to add plus/minus 1 standard
>deviation added to each bar into R cluster bar chart.
>
>You can use the following artificial data.
>
>data cat 1 cat 2
>23     1      1
>45     1      1
>34     1      1
>5      1      1
>32     1      1
>44     1      1
>3      2      1
>1      2      1
>2      2      1
>3      2      1
>4      2      1
>5      1      2
>6      1      2
>7      1      2
>8      1      2
>544    2      2
>78     2      2
>543    2      2
>34     2      2
>89     2      2
>9      1      3
>43     1      3
>23     1      3
>45     1      3
>7      1      3
>5      1      3
>7      1      3
>6      2      3
>867    2      3
>3      2      3
>4      2      3
>5      2      3
>6      2      3
>7      2      3
>8      2      3
>9      2      3
>
>I need to create a bar chart for the mean of data column for each category. I
>know how to create the cluster bar chart. But I need your help with how to add
>plus/minus 1 standard deviation into each bar.
>
>Thank you so much for your helps and for your attention to this matter, and I
>look forward to hearing from you.
>
>
>Regards,
>
>zanaty
>
>
>      
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