[R-sig-Geo] crop or mask large raster on inport

[Zivan Karaman]

Hello Dexter,

I think this could be done with command-line gdal (see, for example,
https://joeyklee.github.io/broc-cli-geo/guide/XX_raster_cropping_and_clipping.html),
but I don't know how to do it in R.

Best regards,
Zivan


Le mar. 24 nov. 2020 à 18:57, Dexter Locke <dexter.locke using gmail.com> a
écrit :

> Dear list,
>
> Is there a way to reduce the spatial extent of an impractically-large
> raster (~50Gb) on import? Can a crop or mask be applied as the large raster
> is read into R to create a more manageable subset?
>
> I've looked at raster and rgdal helpfiles, but have not found this
> functionality. This would be akin to the sf::st_read() 's new "query"
> argument that takes SQL statements for filtering records while reading data
> into R.
>
> The ultimate use case is to summarize a large categorical raster into many
> thousands of polygons, and I thought reading small subsets in at a time
> could be looped through or parallelized for summarizing smaller pieces of
> the data. If there are other approaches to zonal functions (like
> equivalents of ArcMap's Tabulate Area) that could also work.
>
> Thanks for your consideration, Dexter
>
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