xts (version 0.14.1)

.parseISO8601: Internal ISO 8601:2004(e) Time Parser

Description

This function replicates most of the ISO standard for parsing times and time-based ranges in a universally accepted way. The best documentation is the official ISO page as well as the Wikipedia entry for ISO 8601:2004.

Usage

.parseISO8601(x, start, end, tz = "")

Value

A two element list with an entry named ‘first.time’ and one named ‘last.time’.

Arguments

x

A character string conforming to the ISO 8601:2004(e) rules.

start

Lower constraint on range.

end

Upper constraint of range

tz

Timezone (tzone) to use internally.

Author

Jeffrey A. Ryan

Details

The basic idea is to create the endpoints of a range, given a string representation. These endpoints are aligned in POSIXct time to the zero second of the day at the beginning, and the 59.9999th second of the 59th minute of the 23rd hour of the final day.

For dates prior to the epoch (1970-01-01) the ending time is aligned to the 59.0000 second. This is due to a bug/feature in the R implementation of as.POSIXct() and mktime0() at the C-source level. This limits the precision of ranges prior to 1970 to 1 minute granularity with the current xts workaround.

Recurring times over multiple days may be specified using the "T" notation. See the examples for details.

References

https://en.wikipedia.org/wiki/ISO_8601
https://www.iso.org/iso-8601-date-and-time-format.html

Examples

# the start and end of 2000
.parseISO8601('2000')

# the start of 2000 and end of 2001
.parseISO8601('2000/2001')

# May 1, 2000 to Dec 31, 2001
.parseISO8601('2000-05/2001')

# May 1, 2000 to end of Feb 2001
.parseISO8601('2000-05/2001-02')

# Jan 1, 2000 to Feb 29, 2000; note the truncated time on the LHS
.parseISO8601('2000-01/02')

# 8:30 to 15:00 (used in xts subsetting to extract recurring times)
.parseISO8601('T08:30/T15:00')