| chron {chron} | R Documentation |
Create chrononogical objects which represent dates and times of day.
chron(dates., times., format = c(dates = "m/d/y", times = "h:m:s"),
out.format, origin.)
dates. |
character or numeric vector specifying dates. If
character, dates. are assumed to be in one of the date
formats below; if numeric, dates. are assumed to be Julian
dates, i.e., number of days since origin.. |
times. |
optional character or numeric vector specifying times of
day. If character, times. are assumed to be in one of the
time formats below; if numeric, times. are assumed to be
fractions of a day. |
format |
vector or list specifying the input format of the input.
The format can be either strings specifying one of the recognized
formats below or a list of user-supplied functions to convert dates
from character into Julian dates and vice versa.
The dates format can be any permutation of the characters "d", "m", or "y" delimited by a separator
(possibly null), e.g., "m/d/y", "d-m-y", "ymd",
are all valid; the format can also be permutations of the words
"day", "month" and "year" (with non-null
separator), which produces the month name, e.g., "month day
year" produces "April 20 1992", "day mon year"
produces "20 Apr 1992".
The times format can be any permutation of "h", "m",
and "s" separated by any one non-special character. The
default is "h:m:s". |
out.format |
vector or list specifying date and time format for
printing and output. Default is same as format. |
origin. |
a vector specifying the date with respect to which
Julian dates are computed. Default is
c(month = 1, day = 1, year = 1970);
you may set the option chron.origin to specify your own
default, e.g.,
options(chron.origin = c(month=1, day=1, year=1990)). |
An object of class "times" if only times. were
specified, "dates" if only dates., or "chron" if
both dates. and times. were supplied. All these inherit
from class "times".
These objects represent dates and times of day, and allow the
following arithmetic and summaries: subtraction d1-d2,
constant addition d1+constants, all logical comparisons,
summaries min(), max(), and range() (which drop
NAs by default); constants specify days (fractions are converted to
time-of-day, e.g., 2.5 represents 2 days and 12 hours). Operations
such as sorting, differencing, etc., are automatically handled.
There are methods for as.character(), as.numeric(),
cut(), is.na(), print(), summary(),
plot(), lines(), lag(), and the usual subsetting
functions [, [<-.
The functions days(), months(), quarters(),
years(), weeks(), weekdays(), hours(),
minutes(), and seconds() take any chron object as
input and extract the corresponding time interval.
cut() is used to create ordered factors from chron
objects. Chronological objects may be used with the modeling software.
The current implementation of chron objects does not handle
time zones nor daylight savings time.
dates,
times,
julian.default,
cut.dates,
seq.dates.
dts <- dates(c("02/27/92", "02/27/92", "01/14/92",
"02/28/92", "02/01/92"))
dts
# [1] 02/27/92 02/27/92 01/14/92 02/28/92 02/01/92
tms <- times(c("23:03:20", "22:29:56", "01:03:30",
"18:21:03", "16:56:26"))
tms
# [1] 23:03:20 22:29:56 01:03:30 18:21:03 16:56:26
x <- chron(dates = dts, times = tms)
x
# [1] (02/27/92 23:03:19) (02/27/92 22:29:56) (01/14/92 01:03:30)
# [4] (02/28/92 18:21:03) (02/01/92 16:56:26)
# We can add or subtract scalars (representing days) to dates or
# chron objects:
c(dts[1], dts[1] + 10)
# [1] 02/27/92 03/08/92
dts[1] - 31
# [1] 01/27/92
# We can substract dates which results in a times object that
# represents days between the operands:
dts[1] - dts[3]
# Time in days:
# [1] 44
# Logical comparisons work as expected:
dts[dts > "01/25/92"]
# [1] 02/27/92 02/27/92 02/28/92 02/01/92
dts > dts[3]
# [1] TRUE TRUE FALSE TRUE TRUE
# Summary operations which are sensible are permitted and work as
# expected:
range(dts)
# [1] 01/14/92 02/28/92
diff(x)
# Time in days:
# [1] -0.02319444 -44.89335648 45.72052083 -27.05876157
sort(dts)[1:3]
# [1] 01/14/92 02/01/92 02/27/92