GRIBDatasets.jl uses GRIB.jl to provide a higher level interface for reading GRIB files. This package implements the CommonDataModel.jl interface, which mean that the datasets can be accessed in the same way as netCDF files opened with NCDatasets.jl.
To read a GRIB file, just type:
julia> using GRIBDatasets
julia> ds = GRIBDataset("example.grib")
Dataset: example.grib
Group: /
Dimensions
lon = 120
lat = 61
valid_time = 4
Variables
lon (120)
Datatype: Float64 (Float64)
Dimensions: lon
Attributes:
units = degrees_east
long_name = longitude
standard_name = longitude
lat (61)
Datatype: Float64 (Float64)
Dimensions: lat
Attributes:
units = degrees_north
long_name = latitude
standard_name = latitude
valid_time (4)
Datatype: Dates.DateTime (Int64)
Dimensions: valid_time
Attributes:
units = seconds since 1970-01-01T00:00:00
calendar = proleptic_gregorian
long_name = time
standard_name = time
z (120 × 61 × 4)
Datatype: Union{Missing, Float64} (Float64)
Dimensions: lon × lat × valid_time
Attributes:
units = m**2 s**-2
long_name = Geopotential
standard_name = geopotential
t (120 × 61 × 4)
Datatype: Union{Missing, Float64} (Float64)
Dimensions: lon × lat × valid_time
Attributes:
units = K
long_name = Temperature
standard_name = air_temperature
Global attributes
edition = 1
source = /home/tcarion/.julia/dev/GRIBDatasets/test/sample-data/era5-levels-members.grib
centreDescription = European Centre for Medium-Range Weather Forecasts
centre = ecmf
subCentre = 0
Conventions = CF-1.7Indexing on the GRIBDataset object gives you the variable, which is an AbstractArray that can be sliced according to the required dimensions:
julia> t = ds["t"];
julia> t[1:3,1:5,1]
3×5 Matrix{Union{Missing, Float64}}:
233.31 231.276 230.121 229.144 229.072
233.31 231.229 230.053 229.212 228.893
233.31 231.174 229.942 229.064 228.84
julia> ds["valid_time"][:]
4-element Vector{Dates.DateTime}:
2017-01-01T00:00:00
2017-01-01T12:00:00
2017-01-02T00:00:00
2017-01-02T12:00:00The attributes of any variable can be accessed this way:
julia> ds["z"].attrib
Dict{String, Any} with 3 entries:
"units" => "m**2 s**-2"
"long_name" => "Geopotential"
"standard_name" => "geopotential"This package is similar to CfGRIB.jl, but the code has been adapted to be more Julian and to follow the CommonDataModel interface.
It's currently not possible to write the datasets to the GRIB format. If you want to modify the dataset, you need to convert it first to NetCDF and use NCDatasets. Converting a GRIB file to NetCDF is straightforward:
using NCDatasets
using GRIBDatasets
using Downloads: download
grib_file = download("https://github.com/JuliaGeo/GRIBDatasets.jl/raw/98356af026ea39a5ec0b5e64e4289105492321f8/test/sample-data/era5-levels-members.grib")
netcdf_file = "test.nc"
NCDataset(netcdf_file,"c") do ds
write(ds,GRIBDataset(grib_file))
endGRIB format files may have a (very) large amount of different shapes. GRIBDatasets might not work for your specific edge case. If this happens, please open an issue, if possible providing the file triggering the bug.
The windows support is still under development. Most test cases works on windows but a few still fail. See issue GRIB.jl for more information weech/GRIB.jl#14