mondate-methods | R Documentation |
All purpose mondate constructor / coercer.
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, ...)
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. |
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.
signature(x = "mondate")
For mondate
x, this could be a way to copy a mondate
and perhaps change
the mondate
's displayFormat
or timeunits
slots
in the process.
For any class that extends mondate
,
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 when timeunits
= "months",
in which case
the value of x and properties displayFormat
and timeunits
are simply stored.
If timeunits
= "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.
If timeunits
= "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 using as.Date
.
Note that infinite values of x
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 in x
,
and that format is retained as the
displayFormat
of the result unless
the user explicitly provides a value for displayFormat
.
The current set of valid formats is
"%m/%d/%Y", "%m-%d-%Y", "%Y-%m-%d", and "%Y/%m/%d".
If any entries of x
do not convert successfully,
those entries get the value NA
and a warning is issued.
Finally, if format
is not provided and
none of the valid formats successfully converts x
to a date,
then as a last resort
the character string is attempted to be coerced to a
numeric
and then
to a mondate
.
signature(x = "factor")
The character
method is run on as.character(x)
.
signature(x = "array")
If an object x
is an array
,
then this method enables the mondate
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 simply new("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 to numeric
;
if successful, a warning will be issued to check the results
relative to the numeric
conversion, otherwise execution will
be stop
ped.
POSIXt
, yearmon
, yearqtr
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
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