R/calendar.R

In bizdays: Business Days Calculations and Utilities

#' @title Creates calendars
#'
#' @description
#' \code{create.calendar} creates calendars and stores them in the calendar
#' register.
#'
#' @param name calendar's name. This is used to retrieve calendars from
#'             register.
#' @param holidays a vector of Dates which contains the holidays
#' @param weekdays a character vector which defines the weekdays to be used as
#' non-working days (defaults to \code{NULL} which represents an actual
#' calendar). It accepts: \code{sunday}, \code{monday}, \code{tuesday},
#' \code{wednesday}, \code{thursday}, \code{friday}, \code{saturday}.
#' Defining the weekend as nonworking days is
#' \code{weekdays=c("saturday", "sunday")}.
#' @param start.date the date which the calendar starts
#' @param end.date the date which the calendar ends
#' @param adjust.from is a function to be used with the \code{bizdays}'s
#'                    \code{from} argument.
#'                    That function adjusts the argument if it is a nonworking
#'                    day according to calendar.
#' @param adjust.to is a function to be used with the \code{bizdays}'s
#'                  \code{to} argument.
#'                  See also \code{adjust.from}.
#' @param financial is a logical argument that defaults to TRUE.
#'                  This argument defines the calendar as a financial or a non
#'                  financial calendar.
#'                  Financial calendars don't consider the ending business day
#'                  when counting working days in \code{bizdays}.
#'                  \code{bizdays} calls for non financial calendars are
#'                  greater than financial calendars calls by one day.
#'
#' @details
#' The arguments \code{start.date} and \code{end.date} can be set but once
#' they aren't and \code{holidays}
#' is set, \code{start.date} is defined to \code{min(holidays)} and
#' \code{end.date} to \code{max(holidays)}.
#' If holidays isn't set \code{start.date} is set to \code{'1970-01-01'} and
#' \code{end.date} to \code{'2071-01-01'}.
#'
#' \code{weekdays} is controversial but it is only a sequence of nonworking
#' weekdays.
#' In the great majority of situations it refers to the weekend but it is also
#' possible defining
#' it differently.
#' \code{weekdays} accepts a \code{character} sequence with lower case
#' weekdays (
#' \code{sunday}, \code{monday}, \code{tuesday}, \code{wednesday},
#' \code{thursday}, \code{friday}, \code{saturday}).
#' This argument defaults to \code{NULL} because the default intended behavior
#' for
#' \code{create.calendar} returns an \emph{actual} calendar, so calling
#' \code{create.calendar(name="xxx")}
#' returns a \emph{actual} calendar named \emph{xxx}.
#' (for more calendars see
#' \href{https://en.wikipedia.org/wiki/Day_count_convention}{Day Count Convention})
#' To define the weekend as the nonworking weekdays one could simply
#' use \code{weekdays=c("saturday", "sunday")}.
#'
#' The arguments \code{adjust.from} and \code{adjust.to} are used to adjust
#' \code{bizdays}' arguments
#' \code{from} and \code{to}, respectively.
#' These arguments need to be adjusted when nonworking days are provided.
#' The default behavior, setting \code{adjust.from=adjust.previous} and
#' \code{adjust.to=adjust.next},
#' works like Excel's function NETWORKDAYS, since that is fairly used by a
#' great number of practitioners.
#'
#'
#' @section Calendars register:
#'
#' Every named calendar is stored in a register so that it can be retrieved by
#' its name (in \code{calendars}).
#' bizdays' methods also accept the calendar's name on their \code{cal}
#' argument.
#' Given that, naming calendars is strongly recommended.
#'
#' @seealso
#' \code{\link{calendars}}, \code{\link{bizdays}}
#'
#' @name create.calendar
#'
#' @examples
#' # ANBIMA's calendar (from Brazil)
#' holidays <- as.Date(c(
#'   "2015-01-01", "2015-02-16", "2015-02-17", "2015-04-03", "2015-04-21",
#'   "2015-05-01", "2015-06-04", "2015-09-07", "2015-10-12", "2015-11-02",
#'   "2015-11-15", "2015-12-25", "2016-01-01", "2016-02-08", "2016-02-09",
#'   "2016-03-25", "2016-04-21", "2016-05-01", "2016-05-26", "2016-09-07",
#'   "2016-10-12", "2016-11-02", "2016-11-15", "2016-12-25"
#' ))
#' cal <- create.calendar("ANBIMA",
#'   holidays = holidays,
#'   weekdays = c("saturday", "sunday")
#' )
#'
#' # ACTUAL calendar
#' cal <- create.calendar("Actual")
#'
#' # named calendars can be accessed by its name
#' create.calendar(name = "Actual")
#' bizdays("2016-01-01", "2016-03-14", "Actual")
NULL

rev_index <- function(idx) {
  ridx <- cumsum(idx) + 1 - as.integer(idx)
  # ridx[ridx > sum(idx)] <- sum(idx)
  ridx
}

Calendar_ <- function(holidays = integer(0),
                      start.date = NULL, end.date = NULL, name = NULL,
                      weekdays = NULL, adjust.from = adjust.next,
                      adjust.to = adjust.previous, financial = TRUE) {
  if (length(holidays) != 0 && all(is.null(weekdays))) {
    warning(
      "You provided holidays without set weekdays.\n",
      "That setup leads to inconsistencies!"
    )
  }
  that <- list()
  # financial argument
  that$financial <- financial
  # adjust functions
  that$adjust.from <- adjust.from
  that$adjust.to <- adjust.to
  # weekdays
  weekdays_codes <- list(
    monday = 4, tuesday = 5, wednesday = 6, thursday = 0,
    friday = 1, saturday = 2, sunday = 3
  )
  wdays <- unlist(weekdays_codes[weekdays])
  wdays <- if (is.null(wdays)) integer(0) else wdays
  that$weekdays <- weekdays
  # name
  that$name <- name
  # dates and holidays
  that$holidays <- as.Date(holidays, origin = "1970-01-01")
  n.holidays <- as.integer(that$holidays)
  # start.date and end.date
  .has_holidays <- length(holidays) != 0
  if (is.null(start.date)) {
    start.date <- if (.has_holidays) {
      as.Date(min(n.holidays), origin = "1970-01-01")
    } else {
      as.Date("1970-01-01")
    }
  } else {
    start.date <- as.Date(start.date)
  }
  if (is.null(end.date)) {
    end.date <- if (.has_holidays) {
      as.Date(max(n.holidays), origin = "1970-01-01")
    } else {
      as.Date("2071-01-01")
    }
  } else {
    end.date <- as.Date(end.date)
  }
  that$start.date <- start.date
  that$end.date <- end.date
  # dates
  d.dates <- seq(from = start.date, to = end.date, by = "day")
  n.dates <- as.integer(d.dates)
  # is bizday?
  .aux <- function(.) !((. %% 7) %in% wdays || . %in% n.holidays)
  is.bizday_ <- vapply(n.dates, .aux, logical(1))
  that$is.bizday <- function(date) {
    is.bizday_[match(date, n.dates)]
  }
  # bizdays and index
  n.bizdays <- n.dates[is.bizday_]
  index.bizdays <- seq_along(n.bizdays)
  index <- cumsum(is.bizday_) # forward index - the index
  rindex <- rev_index(is.bizday_) # backward index - the reverse index
  # dates table
  dates.table <- cbind(
    dates = n.dates,
    year = as.integer(format(d.dates, "%Y")),
    month = as.integer(format(d.dates, "%m")),
    is_bizday = as.integer(is.bizday_),
    weekday = (n.dates %% 7) + 1
  )
  that$dates.table <- dates.table
  # bizdays
  that$bizdays <- function(from, to) {
    m_from <- match(from, n.dates)
    m_to <- match(to, n.dates)
    # dif from index
    from.idx <- index[m_from]
    to.idx <- index[m_to]
    dif <- to.idx - from.idx
    # dif from reverse index
    from.ridx <- rindex[m_from]
    to.ridx <- rindex[m_to]
    rdif <- to.ridx - from.ridx
    # min is the solution
    pmin(dif, rdif)
  }
  # adjust.next and adjust.previous
  .adjust <- function(dates, offset) {
    idx <- is.bizday_[match(dates, n.dates)]
    idx[is.na(idx)] <- TRUE
    while (!all(idx)) {
      dates[!idx] <- dates[!idx] + offset
      idx <- is.bizday_[match(dates, n.dates)]
      idx[is.na(idx)] <- TRUE
    }
    dates
  }
  that$adjust.next <- function(dates) {
    .adjust(dates, 1L)
  }
  that$adjust.previous <- function(dates) {
    .adjust(dates, -1L)
  }
  # seq
  that$seq <- function(from, to) {
    n.bizdays[which(n.bizdays >= from & n.bizdays <= to)]
  }
  # add
  that$add <- function(date, n) {
    ix <- n > 0
    ref <- integer(length(n))
    ref[ix] <- index[match(date[ix], n.dates)] # index for positive offsets
    # reverse index for negative offsets
    ref[!ix] <- rindex[match(date[!ix], n.dates)]
    .date <- n.bizdays[match(ref + n, index.bizdays)]
    # this is ugly and a post calculation correction
    # if the offset amount is 0 the given date must be returned
    # this doesn't happen for nonbusiness days
    .date[n == 0] <- date[n == 0]
    .date
  }
  class(that) <- "Calendar"
  return(that)
}

compare_functions <- function(x, y) {
  isTRUE(all.equal.language(x, y))
}

adjust_name <- function(x) {
  if (compare_functions(x, adjust.next) || compare_functions(x, following)) {
    "following"
  } else if (compare_functions(x, adjust.previous) ||
    compare_functions(x, preceding)) {
    "preceding"
  } else if (compare_functions(x, adjust.none)) {
    "none"
  }
}

#' @export
#' @rdname create.calendar
create.calendar <- function(name,
                            holidays = integer(0),
                            weekdays = NULL,
                            start.date = NULL, end.date = NULL,
                            adjust.from = adjust.none, adjust.to = adjust.none,
                            financial = TRUE) {
  cal <- Calendar_(
    holidays = holidays, weekdays = weekdays, name = name,
    start.date = start.date, end.date = end.date,
    adjust.from = adjust.from, adjust.to = adjust.to,
    financial = financial
  )
  cal$adjust.from_label <- adjust_name(adjust.from)
  cal$adjust.to_label <- adjust_name(adjust.to)
  .CALENDAR_REGISTER[[cal$name]] <- cal
  invisible(cal)
}

#' @title Calendar's holidays and weekdays
#'
#' @description
#' Returns calendar's list of holidays and weekdays
#'
#' @param cal character with calendar name or the calendar object
#' @param x character with calendar name or the calendar object
#' @param ... unused argument (this exists to keep compliance with
#'            \code{weekdays} generic)
#'
#' @name calendar-holidays-weekdays
#'
#' @examples
#' holidays("actual")
#' weekdays("actual")
#' # empty calls return the default calendar attributes
#' holidays()
#' weekdays()
NULL

#' @export
#' @rdname calendar-holidays-weekdays
holidays <- function(cal) UseMethod("holidays")

#' @export
#' @rdname calendar-holidays-weekdays
holidays.default <- function(cal) {
  if (missing(cal)) {
    cal <- bizdays.options$get("default.calendar")
  } else {
    stop("Invalid calendar: ", cal)
  }
  holidays(cal)
}

#' @export
#' @rdname calendar-holidays-weekdays
holidays.Calendar <- function(cal) cal$holidays

#' @export
#' @rdname calendar-holidays-weekdays
holidays.character <- function(cal) {
  cal <- calendars()[[cal]]
  holidays(cal)
}

#' @export
#' @rdname calendar-holidays-weekdays
weekdays.default <- function(x, ...) {
  if (missing(x)) {
    x <- bizdays.options$get("default.calendar")
  } else {
    stop("Invalid calendar: ", x)
  }
  weekdays(x)
}

#' @export
#' @rdname calendar-holidays-weekdays
weekdays.Calendar <- function(x, ...) x$weekdays

#' @export
#' @rdname calendar-holidays-weekdays
weekdays.character <- function(x, ...) {
  cal <- calendars()[[x]]
  weekdays(cal)
}

#' @export
print.Calendar <- function(x, ...) {
  cal <- x
  lab_holidays <- paste0(length(cal$holidays), " holidays")
  lab_weekdays_1 <- if (length(cal$weekdays)) {
    paste0("(", paste(cal$weekdays, collapse = ", "), ")")
  } else {
    ""
  }
  lab_weekdays <- paste0(length(cal$weekdays), " weekdays ", lab_weekdays_1)
  lab_financial <- if (cal$financial) "financial" else "non financial"
  cat(
    cal$name, lab_financial, "calendar", "\n ",
    lab_holidays, "\n ",
    lab_weekdays, "\n ",
    "range from", format(
      as.Date(cal$start.date, origin = "1970-01-01"),
      "%Y-%m-%d"
    ),
    "to", format(as.Date(cal$end.date, origin = "1970-01-01"), "%Y-%m-%d"),
    "\n"
  )
  cat(
    "bizdays arguments adjust\n",
    sprintf(" %-6s%s", "from:", cal$adjust.from_label), "\n",
    sprintf(" %-6s%s", "to:", cal$adjust.to_label), "\n"
  )
  invisible(x)
}

.CALENDAR_REGISTER <- new.env()
class(.CALENDAR_REGISTER) <- "CalendarRegister"

#' @export
print.CalendarRegister <- function(x, ...) {
  cat("Calendars:", "\n")
  cat(paste(sort(names(.CALENDAR_REGISTER)), collapse = ", "))
  cat("\n")
  invisible(.CALENDAR_REGISTER)
}

#' @title Calendars register
#'
#' @description
#' Every calendar created with \code{create.calendar} is stored in the
#' calendar register.
#' The idea behind this register is allowing calendars to be accessed
#' by its names.
#'
#' @param cals character vector of calendars names
#'
#' @details
#' \code{calendars} returns the object which represents the calendars register.
#' Since the register inherits from \code{environment}, the calendars are
#' retrieved with the \code{[[} operator.
#' But the register object has its own \code{print} generic which helps listing
#' all registered calendars.
#'
#' \code{remove_calendars} remove calendars from the register.
#'
#' @name calendar-register
NULL

#' @export
#' @rdname calendar-register
#' @examples
#' # ACTUAL calendar
#' cal <- create.calendar("Actual")
#' cal <- calendars()[["Actual"]]
#' remove_calendars("Actual")
#' # lists registered calendars
#' calendars()
calendars <- function() {
  .CALENDAR_REGISTER
}

#' @export
#' @rdname calendar-register
remove_calendars <- function(cals) {
  remove(list = cals, envir = .CALENDAR_REGISTER)
}

check_calendar <- function(cal) {
  if (is.null(cal)) {
    stop("Given calendar is NULL.")
  }
  if (is(cal, "character")) {
    if (is.null(calendars()[[cal]])) {
      stop("Invalid calendar name: ", cal)
    }
    calendars()[[cal]]
  } else if (is(cal, "Calendar")) {
    cal
  } else {
    stop("Invalid argument")
  }
}

#' @export
#' @rdname calendar-register
#' @examples
#' has_calendars(c("actual", "weekends"))
has_calendars <- function(cals) {
  cals %in% ls(.CALENDAR_REGISTER)
}