NLP (version 0.2-0)

datetime: Parse ISO 8601 Date/Time Strings

Description

Extract date/time components from strings following one of the six formats specified in the NOTE-datetime ISO 8601 profile (https://www.w3.org/TR/NOTE-datetime).

Arguments

x

a character vector.

Value

An object inheriting from class "ISO_8601_datetime" with the extracted date/time components.

Details

For character strings in one of the formats in the profile, the corresponding date/time components are extracted, with seconds and decimal fractions of seconds combined. Other (malformed) strings are warned about.

The extracted components for each string are gathered into a named list with elements of the appropriate type (integer for year to min; double for sec; character for the time zone designator). The object returned is a (suitably classed) list of such named lists. This internal representation may change in future versions.

One can subscript such ISO 8601 date/time objects using [ and extract components using $ (where missing components will result in NAs), and convert them to the standard R date/time classes using as.Date(), as.POSIXct() and as.POSIXlt() (incomplete elements will convert to suitably missing elements). In addition, there are print() and as.data.frame() methods for such objects.

Examples

# NOT RUN {
## Use the examples from <https://www.w3.org/TR/NOTE-datetime>, plus one
## in UTC.
x <- c("1997",
       "1997-07",
       "1997-07-16",
       "1997-07-16T19:20+01:00",
       "1997-07-16T19:20:30+01:00",
       "1997-07-16T19:20:30.45+01:00",
       "1997-07-16T19:20:30.45Z")
y <- parse_ISO_8601_datetime(x)
y
## Conversions: note that "incomplete" elements are converted to
## "missing".
as.Date(y)
as.POSIXlt(y)
## Subscripting and extracting components:
head(y, 3)
y$mon
# }