Create a Chronological Object
Create chronological 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, |
times. |
optional character or numeric vector specifying times of
day. If character, |
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
The times format can be any permutation of |
out.format |
vector or list specifying date and time format for
printing and output. Default is same as |
origin. |
a vector specifying the date with respect to which
Julian dates are computed. Default is
|
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.
If x is character then it will be converted using
as.POSIXct (with the format argument, if any, passed to
as.POSIXct) and tz = "GMT" and then converted
to chron. If x is numeric and format
is not specified then it will be converted to chron
using chron(x). If x is numeric and format
is specified then x will be converted to character and
then processed using as.POSIXct as discussed above. If the
format is specified as NULL it will be treated the same as if
it were missing.
The current implementation of chron objects does not handle
time zones nor daylight savings time.
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 02/27/92Please choose more modern alternatives, such as Google Chrome or Mozilla Firefox.