Defines a "WeekDays" constant and a "dailyCalendar" function

dailyCalendar.R

WeekDays <- function(startOn = "Monday", abbreviate = FALSE) {
  WD <- c("Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday", "Sunday")
  x <- match(startOn, WD)
  WD <- WD[c(x:7, setdiff(1:7, x:7))]
  if (isTRUE(abbreviate)) {
    substring(WD, 0, 3)
  } else WD
}


dailyCalendar <- function(startDate = Sys.Date(), days = 30, startOn = "Monday", fancy = FALSE) {
  require(reshape2)
  inDailyTs <- ts(as.character(seq(as.Date(startDate),
                                   length.out = days, by = 1)),
                  frequency = 7)
  temp <- data.frame(
    weekday = factor(weekdays(as.Date(as.character(inDailyTs))), WeekDays(startOn)),
    date = inDailyTs, 
    month = format(as.Date(as.character(inDailyTs)), "%B"),
    day = format(as.Date(as.character(inDailyTs)), "%d"),
    year = format(as.Date(as.character(inDailyTs)), "%Y"),
    stringsAsFactors = FALSE)
  temp$week <- cumsum(temp$weekday == startOn)
  
  if (isTRUE(fancy)) {
    A <- paste(temp$month, temp$year)
    X <- split(temp, factor(A, unique(A), ordered=TRUE))
    lapply(X, function(y) {
      dcast(y, week ~ weekday, value.var = "day", fill = "", drop=FALSE)[WeekDays(startOn)]
    })
  } else {
    dcast(temp, week ~ weekday, value.var = "date", fill = "")[WeekDays(startOn)]
  }
}

Examples

WeekDays simply defines a character constant of the (English) weekday names, optionally abbreviated, and starting on an arbitrary day of the week (defaulting with starting on "Monday").

WeekDays()
# [1] "Monday"    "Tuesday"   "Wednesday" "Thursday"  "Friday"    "Saturday" 
# [7] "Sunday"   
WeekDays("Thursday", TRUE)
# [1] "Thu" "Fri" "Sat" "Sun" "Mon" "Tue" "Wed"

dailyCalendar creates a calendar view of a range of daily dates.

dailyCalendar(startDate="2013-12-27", days=10)
#       Monday    Tuesday  Wednesday   Thursday     Friday   Saturday     Sunday
#1                                             2013-12-27 2013-12-28 2013-12-29
#2 2013-12-30 2013-12-31 2014-01-01 2014-01-02 2014-01-03 2014-01-04 2014-01-05

dailyCalendar(startDate="2013-12-27", days=10, startOn="Friday")
#       Friday   Saturday     Sunday     Monday    Tuesday  Wednesday   Thursday
#1 2013-12-27 2013-12-28 2013-12-29 2013-12-30 2013-12-31 2014-01-01 2014-01-02
#2 2014-01-03 2014-01-04 2014-01-05           

There is also a "fancy" view for dailyCalendar:

dailyCalendar(startDate="2013-12-27", days=30, startOn="Friday", fancy=TRUE)
# $`December 2013`
#   Friday Saturday Sunday Monday Tuesday Wednesday Thursday
#1     27       28     29     30      31                   
# 
# $`January 2014`
#   Friday Saturday Sunday Monday Tuesday Wednesday Thursday
#1                                              01       02
#2     03       04     05     06      07        08       09
#3     10       11     12     13      14        15       16
#4     17       18     19     20      21        22       23
#5     24       25                 

It might be interesting to modify the Weekdays function so that it returns weekdays in the language of the locale. I think this would do it.

WD<-strftime(seq(as.Date('2013-11-18'),(as.Date('2013-11-18')+6),by=1),'%A')

But then startsOn would have to modified to either be an integer, and to handle if the user inputs a day of week in a non-English language.

@nograpes, I thought about that but I have not had much time to look into how locale settings work in R. I'll check out your suggestion when I have some time.