Re: GMT 4: combining GRD files into one FILE with several LAYERS

I never tried it but it's not impossible that you can do what you want 
by forcing the writing via GDAL.
Note that an alternative to a stack of 2D grids would be to have 256 
grids written as individual grids inside the netCDF file (SUBDATASETS in 
GDAL parlance).
GMT could easily read those individual arrays and perhaps you could 
force the updating via a GDAL write. See this for an example of syntax 
for reading

http://gmtrac.soest.hawaii.edu/doc/5.1.0/GMT_Docs.html#reading-more-complex-multi-band-images-or-grids

> This data is essentially something along the lines of
>
> 	layer 1 = topogrpahy
> 	layer 2 = gravity
> 	layer 43= FFT(gravity) + sqrt (topo)  (or something crazy like that)...
>
> and so on.
>
> In effect a global gird of all known “measurements", not so much “n dimensional” although that is certainly a good way to think of it.
>
> Does that change any facts, your opinion, etc…
>
> -jj
>
>
> On Feb 10, 2014, at 5:39 PM, Paul Wessel<[email protected]>  wrote:
>
>> Hi JJ_
>>
>> GMT can read from layer "a" but does not write 3-D grids.  Given that I would not try to do a 256-layer file.
>>
>> -p
>>
>> On Feb 10, 2014, at 9:46 AM, Becker, Joseph J.<[email protected]>  wrote:
>>
>>> I have 256 global grids at 15 second resolution; e.g. ~16 GB grd files * 256 grids =  4 TB of data.
>>>
>>> I want to automate some processing that uses tiny patches (16x16 nodes) of each and every one of these 256 files. And I step that over the globe.
>>>
>>> Off hand it seems like it might make sense (code re-use and simplicity) to combine all that data into a single grid with 256 layers.
>>>
>>> Is this practical?
>>>
>>> Anyone have some examples of doing things like this:
>>>
>>> 	grdmath on layer "a" writing result to layer "b"
>>>
>>> 	grdmask xy files>  "layer"
>>>
>>> and so on.
>>>
>>> thanks!
>>>
>>>
>>> -jj
>>>
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> To unsubscribe, send the message "signoff gmt-help" to [email protected]
>
>

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