setwd("rdatasets")

# Read dataset with columns in fixed with format.
# Specify widths, which are the column widths for each
# variable. Use dummy variables for columns which are not
# needed and which will be discarded later.
students <- read.fwf("students.txt", 
  widths=c(10, 1, 5, 1, 4),
  col.names=c("dummy1", "gen", "dummy2", "yr", "dummy3"))
                    
print(students)

# Discard unwanted columns in dummy variables.
# The index c(2, 4) means keep variables 2 and 4.
students2 <- students[ , c(2, 4)]
print(students2)

# Summarize data with table function.
# You could have used the following line instead:
# tab <- table(students[ , c(2, 4)])
tab <- table(students2)
print(tab)

# Send graphs to PDF file.
pdf("students.pdf")

# Create stacked bar plot.  font.sub=2 means bold font.
barplot(tab, main="Students in Consolidated High",
  xlab="Year in School", ylab="Number of Students",
  names.arg=c("Freshman", "Sophomore", "Junior", "Senior"),
  font.main=2, col=c("red", "blue"))
legend(x="topright", legend=c("Female", "Male"),
  fill=c("red", "blue"))

# Create side-by-side barplot.
barplot(tab, main="Students in Consolidated High",
  xlab="Year in School", ylab="Number of Students",
  names.arg=c("Freshman", "Sophomore", "Junior", "Senior"),
  font.main=2, beside=TRUE, col=c("red", "blue"))
legend(x="topright", legend=c("Female", "Male"),
  fill=c("red", "blue"))

# Send graphics back to viewer.
dev.off( )