# boxplots

mydataframe <- read.delim("http://www.robin-beaumont.co.uk/virtualclassroom/book2data/pain_medication.dat", header=TRUE)
names(mydataframe)

# local copy
 mydataframe <- read.delim("D:\\web_sites_mine\\HIcourseweb new\\book2data\\pain_medication.dat", header=TRUE)
names(mydataframe)
str(mydataframe)

# R Commander auto generated - uses the Rcmdr function Boxplot (in the car package) 
# instead of the generic boxplot()
library(car)
Boxplot(time~dosage, data=mydataframe, id.method="y")

# now using the generic boxplot()

newdata <- split(mydataframe$time, mydataframe$dosage)
boxplot(newdata, col = "lavender", notch = TRUE, varwidth = TRUE)
or 
boxplot(mydataframe$time ~ mydataframe$dosage, col = "lavender", notch = TRUE, varwidth = TRUE)

# use the medlwd option to increase the width of the median line
boxplot(newdata, col = "grey90", medlwd=5)
boxplot(mydataframe$time ~ mydataframe$dosage, col = "lavender", notch = TRUE, varwidth = TRUE, medlwd=10)

# R Commander auto generated
Boxplot(values~ind, data=mydataframe, id.method="y")
Boxplot(values~ind, data=mydataframe, id.method="n")
Boxplot(values~ind, data=mydataframe, id.method="identify")