I am working with multiple netCDF images from NASA GPM. I have to make a cumulative hydrology map by adding all the stacks of images together. For now, I have the simple code below but it is impossible to apply it for 868 images.
How can i automate the process?
> rr1 rr2 rr3 print(rr3)
Dear Helen,
You can open all the netCDF files at once using raster::stack(x), where x is a character vector containing the filenames. Then, use raster::calc(x, fun = sum), where x is the RasterStack object loaded previously. Alternatively, you can use sum(s), where s is the RasterStack object.
HTH,
Ákos
the raster package is built on top of gdal, and thus you can use it to read subsets of the image. If you check the help of raster, you can specify a reading extent, which, like in gdal, will be used to read only the subset. By iterating through a set of equal intervals along e.g. the y axis, you can perform your calculation with low memory requirements. If you combine that with e.g. foreach, you can parallelize your processing scheme by treating each piece of the image(s) as a task and combine the output at the end with e.g. merge.
Thank you Ákos Bede-Fazekas I have managed to stack the images and the additions now seem simple
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