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Convert an object to a date or date-time

Source: R/coercion.r
as_date.Rd

Convert an object to a date or date-time

Usage

as_date(x, ...)

# S4 method for ANY
as_date(x, ...)

# S4 method for POSIXt
as_date(x, tz = NULL)

# S4 method for numeric
as_date(x, origin = lubridate::origin)

# S4 method for character
as_date(x, tz = NULL, format = NULL)

as_datetime(x, ...)

# S4 method for ANY
as_datetime(x, tz = lubridate::tz(x))

# S4 method for POSIXt
as_datetime(x, tz = lubridate::tz(x))

# S4 method for numeric
as_datetime(x, origin = lubridate::origin, tz = "UTC")

# S4 method for character
as_datetime(x, tz = "UTC", format = NULL)

# S4 method for Date
as_datetime(x, tz = "UTC")

Arguments

x

a vector of POSIXt, numeric or character objects

...

further arguments to be passed to specific methods (see above).

tz

a time zone name (default: time zone of the POSIXt object x). See OlsonNames().

origin

a Date object, or something which can be coerced by as.Date(origin, ...) to such an object (default: the Unix epoch of "1970-01-01"). Note that in this instance, x is assumed to reflect the number of days since origin at "UTC".

format

format argument for character methods. When supplied parsing is performed by parse_date_time(x, orders = formats, exact = TRUE). Thus, multiple formats are supported and are tried in turn.

Value

a vector of Date objects corresponding to x.

Compare to base R

These are drop in replacements for as.Date() and as.POSIXct(), with a few tweaks to make them work more intuitively.

  • Called on a POSIXct object, as_date() uses the tzone attribute of the object to return the same date as indicated by the printed representation of the object. This differs from as.Date, which ignores the attribute and uses only the tz argument to as.Date() ("UTC" by default).

  • Both functions provide a default origin argument for numeric vectors.

  • Both functions will generate NAs for invalid date format. Valid formats are those described by ISO8601 standard. A warning message will provide a count of the elements that were not converted.

  • as_datetime() defaults to using UTC.

Examples

dt_utc <- ymd_hms("2010-08-03 00:50:50")
dt_europe <- ymd_hms("2010-08-03 00:50:50", tz = "Europe/London")
c(as_date(dt_utc), as.Date(dt_utc))
#> [1] "2010-08-03" "2010-08-03"
c(as_date(dt_europe), as.Date(dt_europe))
#> [1] "2010-08-03" "2010-08-02"
## need not supply origin
as_date(10)
#> [1] "1970-01-11"
## Will replace invalid date format with NA
dt_wrong <- c("2009-09-29", "2012-11-29", "2015-29-12")
as_date(dt_wrong)
#> Warning:  1 failed to parse.
#> [1] "2009-09-29" "2012-11-29" NA