# Help file for the class of Date objects:

help(Dates)

# Help file for converting Date objects using as.Date:

help(as.Date)

# Example of a series of dates:

dates <- c("02/27/92", "02/27/92", "01/14/92", "02/28/92", "02/01/92")

is.character(dates)

dates.of.interest <- as.Date(dates, "%m/%d/%y")

dates.of.interest

weekdays(dates.of.interest)

diff(dates.of.interest) # number of days between the dates

todays.date <- Sys.Date() 

# formatting today's date with month as a word:

format(todays.date, "%d %b %Y") 

# Some more dates in character form:

more.dates <- c("1jan1960", "2jan1960", "31mar1960", "30jul1960")

# Converting to Date format:

dates.long.ago <- as.Date(more.dates, "%d%b%Y")

# Note that the capital Y was needed for 
# the four-digit representation of year.

# Reading the football data:

football.dfr<-as.data.frame(scan("http://people.stat.sc.edu/hitchcock/football_data.txt",sep=',',skip=1, what=list(game.date='character',visitor.team='character',visitor.score=0, home.team='character',home.score=0),multi.line=T))

attach(football.dfr)

game.date <- as.Date(as.character(game.date), "%m/%d/%Y")

# The as.character() is necessary to convert game.date to a character object 
# It had been changed to a factor when the data frame was created

wk.day <- weekdays(game.date)

football.dfr <- cbind(wk.day, football.dfr)

football.dfr


?DateTimeClasses