[R-sig-Geo] Raster to rasterbrick does not preserve Date/Time

[Ben Tupper]

Hi,

I'm not sure about reading the datetime stamp directly form the file, but you have enough info to convert the z-value which is well described in your ncdf.  I'm not familiar with the '%.f' format specifier, but it looks like it is a fractional day.  Something like this perhaps will work?

z      <- raster::getZ(rbick)
z0     <- floor(z)
zf     <- z - z0
dt     <- as.POSIXct(as.character(z0), format = "%Y%m%d") + 24*60*60*zf
rbrick <- raster::setZ(rbrick, z, name = 'datetime')

You'll need to think through the timezone issues that might arise.  as.POSIXct() has arguments that can help you with that.

Cheers,
Ben


> On Nov 4, 2018, at 12:39 PM, Miluji Sb <milujisb using gmail.com> wrote:
> 
> Dear all,
> 
> I have a raster with multiple variables and date/time information;
> 
>      time  Size:17164   *** is unlimited ***
>            standard_name: time
>            bounds: time_bnds
>            units: day as %Y%m%d.%f
>            calendar: proleptic_gregorian
>        bnds  Size:2
> 
> My goal is to convert the raster file to rasterbrick for extraction
> purposes;
> 
> rbrick <- brick(r,  values=TRUE, varname="var1")
> 
> However, after conversion - the date/time information is not preserved. How
> can I preserve this information?
> 
> class       : RasterBrick
> dimensions  : 600, 1440, 864000, 17164  (nrow, ncol, ncell, nlayers)
> resolution  : 0.25, 0.25  (x, y)
> extent      : -180, 180, -60, 90  (xmin, xmax, ymin, ymax)
> coord. ref. : +proj=longlat +datum=WGS84 +ellps=WGS84 +towgs84=0,0,0
> data source : /work/ncfile.nc4
> names       : X19700101.4375, X19700102.4375, X19700103.4375,
> X19700104.4375, X19700105.4375, X19700106.4375, X19700107.4375,
> X19700108.4375, X19700109.4375, X19700110.4375, X19700111.4375,
> X19700112.4375, X19700113.4375, X19700114.4375, X19700115.4375, ...
> z-value     : 19700101.4375, 20161231.4375 (min, max)
> varname     : var1
> 
> Any help will be greatly appreciated!
> 
> Sincerely,
> 
> Milu
> 
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> 
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Ben Tupper
Bigelow Laboratory for Ocean Sciences
60 Bigelow Drive, P.O. Box 380
East Boothbay, Maine 04544
http://www.bigelow.org

Ecological Forecasting: https://eco.bigelow.org/