mondate-methods {mondate} | R Documentation |
Create an instance of the mondate class
Description
All purpose mondate constructor / coercer.
Usage
mondate(x,
displayFormat = getOption("mondate.displayFormat",
default = .get.default.displayFormat()),
timeunits = getOption("mondate.timeunits",
default = .get.default.timeunits()),
...)
## S4 method for signature 'mondate'
mondate(x, displayFormat, timeunits, formatFUN, ...)
## S4 method for signature 'numeric'
mondate(x, displayFormat, timeunits, ...)
## S4 method for signature 'Date'
mondate(x, displayFormat, timeunits, ...)
## S4 method for signature 'POSIXt'
mondate(x, displayFormat, timeunits, ...)
## S4 method for signature 'character'
mondate(x, displayFormat = "keep", timeunits, format, ...)
## S4 method for signature 'array'
mondate(x, displayFormat, timeunits, ...)
## S4 method for signature 'missing'
mondate(x, displayFormat, timeunits, ...)
## S4 method for signature 'ANY'
mondate(x, displayFormat, timeunits, ...)
Arguments
x |
an R object to convert to a |
displayFormat |
character string representing the date format with which to display
the |
timeunits |
character string "months" (default), "years", or "days" indicating the units in which date arithmetic will be carried out. |
formatFUN |
format function for converting a mondate to character.
In case of conversion from |
format |
format string for converting a character to a Date
(using |
... |
arguments to be passed to other methods. |
Details
Package users can change the default values of
displayFormat
and timeunits
using options()
with the names
"mondate.displayFormat" and "mondate.timeunits", respectively.
Warning! Use with care!
No checks are performed if and when the options are established.
It is up to the user to ensure the new defaults are valid –
displayFormat
must be appropriate for formatting dates in R and
timeunits
must be one of
"months", "years", or "days".
See an example below.
Methods
signature(x = "mondate")
-
For
mondate
x, this could be a way to copy amondate
and perhaps change themondate
'sdisplayFormat
ortimeunits
slots in the process. For any class that extendsmondate
, use of this method will return the underlying mondate class without additional slots (if any) of the subclass. signature(x = "numeric")
-
For
numeric
x, the simplest case is whentimeunits
= "months", in which case the value of x and propertiesdisplayFormat
andtimeunits
are simply stored. Iftimeunits
= "years" then it is presumed that the value of x represents the number of years since the beginning of the millennium, in which case the value of x is multiplied by 12 and then stored. Iftimeunits
= "days" then it is presumed that the value of x represents the number of days since the beginning of the millennium, in which case the value is calculated usingas.Date
. Note that infinite values ofx
are allowed, helpful in actuarial ("at ultimate") longitudinal, and time series modeling. signature(x = "Date")
signature(x = "POSIXt")
-
For a date x,
as.POSIXlt
is used to convert to an ISO standard date, from which the number of months of that day since the beginning of the millennium is calculated. signature(x = "character")
-
If
format
is provided, then that format is used to attempt to convert the character value to a date. Otherwise, characters are converted to dates using the first format found in the set of valid formats that successfully converts the first non-NA entry inx
, and that format is retained as thedisplayFormat
of the result unless the user explicitly provides a value fordisplayFormat
. The current set of valid formats is "%m/%d/%Y", "%m-%d-%Y", "%Y-%m-%d", and "%Y/%m/%d". If any entries ofx
do not convert successfully, those entries get the valueNA
and a warning is issued. Finally, ifformat
is not provided and none of the valid formats successfully convertsx
to a date, then as a last resort the character string is attempted to be coerced to anumeric
and then to amondate
. signature(x = "factor")
-
The
character
method is run onas.character(x)
. signature(x = "array")
-
If an object
x
is anarray
, then this method enables themondate
to inherit its shape. After that, other "signatures" take over. signature(x = "missing")
-
Enables the call
mondate()
to work. Useful for prototypes, e.g. Body of method is simplynew("mondate")
. signature(x = "ANY")
-
For any other class of x an attempt will be made to convert to
Date
("as.Date(x)
"). If unsuccessful, an attempt will be made to convert tonumeric
; if successful, a warning will be issued to check the results relative to thenumeric
conversion, otherwise execution will bestop
ped.
See Also
Examples
mondate("1-31-2010") # Jan. 31, 2010
mondate(60) # 60 months after 12/31/1999, so Dec. 31, 2004
dat <- as.Date("2010-1-31")
(M <- mondate(dat)) # Jan. 31, 2010
x <- 12 * 1:6
mondate(x) # first 6 yearends in 2000's
y <- x + 12
mondate(cbind(x,y)) # bounding dates of first 6 years of millennium
(y <- mondate(1:6,timeunits="years")) # first 6 yearends, 'years' timeunits
# The results of date arithmetic on y will be displayed in "years".
# E.g., the differences of y can be calculated as:
tail(y,-1) - head(y,-1)# vector of five 1's, with "timeunits" attribute = "years"
as.numeric(x)
as.numeric(y) # the underlying numeric representations are the same
# Demonstrating "infinite" dates
y <- c(y,Inf)
y # last element shows as Inf
tail(y,-1) - head(y,-1)# last element is now infinity
# The zoo examples point out a difference between zoo and mondate.
# zoo assumes that the zero-th part of a month or quarter is the first
# day of the month or quarter, whereas mondate assumes that it is
# the instant before the first day of the month or quarter.
# Since frac=0 is zoo's as.Date coersion default, a month or quarter in
# zoo's sense converts to the end of the first day rather than
# the beginning.
library(zoo)
x <- ts(1:10, frequency = 4, start = c(1959, 2)) # starting 2nd qtr of 1959
x
# There is no method for class 'ts' so x is coerced (successfully)
# because that class has an as.Date method, but with a warning.
# The result is a vector of length 10 representing the close of business
# at the end of the first day of each of the given quarters.
mondate(x)
# The yearmon class will identify any day in June 2010 with that month.
as.yearmon("2010-6-15")
mondate(as.yearmon("2010-6-15")) # end of first day of June 2010
mondate(as.yearmon("2010-6-15", frac=1)) # end of last day of June 2010
mondate(as.yearqtr("2010-2", frac=1)) # same
# The if missing, displayFormat will be determined from the character input
x <- mondate("2010-12-31")
x # x displays in the input European format
# The provided, displayFormat must match the format of the character input
# or NA's will result.
mondate("2010-12-31", displayFormat = "%m-%d-%Y") # results in NA
# Always display x using just the year
x <- mondate(as.Date("2012-3-1"), displayFormat="%Y")
x # shows as the year 2012, but month and day are nevertheless retained
month(x) # 3
day(x) # 1
# Change the default displayFormat to only display the year and month
options(mondate.displayFormat = "%Y-%m")
y <- mondate(as.Date("2013-12-31"))
y
# mondate: timeunits="months"
# [1] 2013-12
# Previous mondate instances retain their display formats:
x
# mondate: timeunits="months"
# [1] 2012