Description Usage Arguments Details Value Author(s) References See Also Examples
There are many varieties, according to the value of type
as defined
in ‘Details’.
1 2  numberAsPOSIXct(t, type = c("unix", "matlab", "gps", "argo", "ncep1", "ncep2",
"sas", "spss", "yearday"), tz = "UTC")

t 
an integer corresponding to a time, in a way that depends on

type 
the type of time (see “Details”). 
tz 
a string indicating the time zone, used only for unix and matlab times, since GPS times are always referenced to the UTC timezone. 
"unix"
employs Unix times, measured in seconds since the start
of the year 1970.
"matlab"
employs Matlab times, measured in days since what
MathWorks [1] calls “January 0, 0000” (i.e. ISOdatetime(0, 1, 1, 0,
0, 0)
in R notation).
"gps"
employs the GPS convention. For this, t
is a
twocolumn matrix, with the first column being the the GPS "week"
(referenced to 19990822) and the second being the GPS "second" (i.e. the
second within the week). Since the GPS satellites do not handle leap
seconds, the Rdefined .leap.seconds
is used for corrections.
"argo"
employs Argo times, measured in days since the start of
the year 1900.
"ncep1"
employs NCEP times, measured in hours since the start
of the year 1800.
"ncep2"
employs NCEP times, measured in days since the start of
the year 1. (Note that, for reasons that are unknown at this time, a simple
R expression of this definition is out by two days compared with the UDUNITS
library, which is used by NCEP. Therefore, a twoday offset is applied. See
[2, 3].)
"sas"
employs SAS times, indicated by type="sas"
, have
origin at the start of 1960.
"spss"
employs SPSS times, in seconds after 15821014.
"yearday"
employs a convention in which t
is a
twocolumn matrix, with the first column being the year, and the second the
yearday (starting at 1 for the first second of January 1, to match the
convention used by SeaBird CTD software).
A POSIXct
time vector.
Dan Kelley
[1] Matlab times: http://www.mathworks.com/help/matlab/ref/datenum.html
[2] NCEP times: https://www.esrl.noaa.gov/psd/data/gridded/faq.html#3
[3] problem with NCEP times: https://github.com/dankelley/oce/issues/738
Other things related to time: ctimeToSeconds
,
julianCenturyAnomaly
,
julianDay
, numberAsHMS
,
secondsToCtime
,
unabbreviateYear
1 2 3 4  numberAsPOSIXct(0) # unix time 0
numberAsPOSIXct(1, type="matlab") # matlab time 1
numberAsPOSIXct(cbind(566, 345615), type="gps") # Canada Day, zero hour UTC
numberAsPOSIXct(cbind(2013, 0), type="yearday") # start of 2013

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