I am using pygrib to open GFS data, I want the data to be in unstructured format (not the default option). in short, How can I set expand_reduce to False?
grbs = pygrib.open(filename)
print(grbs[1].expand_reduce) # this prints True (default)
In the docs (https://jswhit.github.io/pygrib/api.html) it says:
@ivar expand_reduced: If True (default), reduced lat/lon and gaussian grids will be expanded to regular grids when data is accessed via "values" key. If False, data is kept on unstructured reduced grid, and is returned in a 1-d array.
I took a look at the source code (https://searchcode.com/file/11567389/pygrib.pyx/) and found that it is a private attribute, and that it is hard coded in the _create_gribmessage method.
625 cdef _create_gribmessage(grib_handle *gh, object messagenumber):
626 """factory function for creating gribmessage instances"""
627 cdef gribmessage grb = gribmessage.__new__(gribmessage)
628 grb.messagenumber = messagenumber
629 grb.expand_reduced = True ## HERE <---
630 grb._gh = grib_handle_clone(gh)
631 grb._all_keys = grb.keys()
632 grb._ro_keys = grb._read_only_keys()
633 grb._set_projparams() # set projection parameter dict.
634 return setdates(grb)
The solution is to call expand_grid, this will modify the expand_reduced:
grbs[1].expand_grid(False)
print(grbs[1].expand_reduce) # this now prints False