wp_date() provides a generic function and several methods to transform
something into a date, just like as.Date() from the base package.
While most methods were copied 1:1 from as.Date() some changes were made that
alter the usual behavior: (1) Whenever wp_date() is applied to an empty
string "" or any other not-standard-unambiguous format the function
will return NA and throw out a warning instead of simply kill itself
with an error. (2) Whenever, as.Date usually is in the need of an origin
supplied and does not get one wp_date() will assume the origin to be
"1970-01-01" and throw an error instead of kill itself with an error. All
these changes are made with the special purpose to make wp_trend()
also with dirty, unreasonable data (e.g. "" or "2012-13-01" or "2012-02-32")
and are not recommended for any other than wikipediatrend internal use.
wp_date(x, ...)# S3 method for character
wp_date(x, format = "", ...)
# S3 method for default
wp_date(x, ...)
# S3 method for numeric
wp_date(x, origin, ...)
# S3 method for dates
wp_date(x, ...)
# S3 method for factor
wp_date(x, ...)
# S3 method for POSIXct
wp_date(x, tz = "UTC", ...)
# S3 method for POSIXlt
wp_date(x, ...)
See ?as.Date
See ?as.Date
See ?as.Date
See ?as.Date
See ?as.Date
character: Difference to as.Date.character(): Failing to
parse the date, wp_date() will give return a warning and NA
instead of killing itself with an error.
default: same as as.Date()
numeric: Difference to as.Date.character(): Whenever an
origin is needed but not supplied instead of breaking, wp_date()
will raise a warning and proceed by assuming "1970-01-01" to be the origin
instead of killing itself with an error.
dates: same as as.Date()
factor: same as as.Date()
POSIXct: same as as.Date()
POSIXlt: using as.Date()