Returns a map representing a NetCDF group. The map contains the keys name = group name, root = true if this is the root group, attributes = vector of group attributes, dimensions = dimensions of variables in the group variables = vector of variables in the group and obj = the low level NetCDF group object.

Returns internal representation of NetCDF group as a map

return a group given the full group name.

Returns a map for the root group containing keys for :name, :root?, :attributes, :dimensions, :variables, :obj and :children. The nc argument is a netcdf file object returned from a call to open or open-in-memory.