"""Read generic netCDF spectra files."""
from xarray.backends import BackendEntrypoint
from wavespectra.specdataset import SpecDataset
from wavespectra.input import open_netcdf
from wavespectra.core.attributes import attrs, set_spec_attributes
[docs]
def read_netcdf(
filename_or_fileglob,
chunks={},
freqname=attrs.FREQNAME,
dirname=attrs.DIRNAME,
sitename=attrs.SITENAME,
specname=attrs.SPECNAME,
lonname=attrs.LONNAME,
latname=attrs.LATNAME,
timename=attrs.TIMENAME,
):
"""Read Spectra from generic netCDF format.
Args:
- filename_or_fileglob (str, list, filelike): filename, fileglob specifying multiple
files, or filelike object to read.
- chunks (dict): chunk sizes for dimensions in dataset. By default
dataset is loaded using single chunk for all dimensions (see
xr.open_mfdataset documentation).
- <coord>name :: coordinate name in netcdf, used for standarising
dataset.
Returns:
- dset (SpecDataset): spectra dataset object read from netcdf file
Note:
- Assumes frequency in :math:`Hz`, direction in :math:`degree` and
spectral energy in :math:`m^{2}degree^{-1}{s}`.
- If file is large to fit in memory, consider specifying chunks for
'time' and/or 'station' dims.
"""
dset = open_netcdf(filename_or_fileglob, chunks=chunks)
coord_map = {
freqname: attrs.FREQNAME,
dirname: attrs.DIRNAME,
lonname: attrs.LONNAME,
latname: attrs.LATNAME,
sitename: attrs.SITENAME,
specname: attrs.SPECNAME,
timename: attrs.TIMENAME,
}
dset = dset.rename({k: v for k, v in coord_map.items() if k in dset})
set_spec_attributes(dset)
return dset
class NetCDFBackendEntrypoint(BackendEntrypoint):
"""Netcdf backend engine."""
def open_dataset(
self,
filename_or_obj,
*,
drop_variables=None,
freqname=attrs.FREQNAME,
dirname=attrs.DIRNAME,
sitename=attrs.SITENAME,
specname=attrs.SPECNAME,
lonname=attrs.LONNAME,
latname=attrs.LATNAME,
timename=attrs.TIMENAME,
):
return read_netcdf(
filename_or_obj,
freqname=freqname,
dirname=dirname,
sitename=sitename,
specname=specname,
lonname=lonname,
latname=latname,
timename=timename,
)
def guess_can_open(self, filename_or_obj):
return False
description = "Open generic netcdf spectra files as a wavespectra dataset."
url = "https://github.com/wavespectra/wavespectra"
