Source code for wavespectra.input.xwaves

"""Read XWaves MAT files"""
from xarray.backends import BackendEntrypoint
import datetime
import xarray as xr
from scipy.io import loadmat

from wavespectra.specdataset import SpecDataset
from wavespectra.core.attributes import attrs, set_spec_attributes
from wavespectra.core.utils import R2D




def read_xwaves(filename):
    """Read Spectra from XWaves MAT format.

    Args:
        - filename (str): File to read.

    Returns:
        - dset (SpecDataset): spectra dataset object read from netcdf file.

    """
    # Load and construct dataset
    data = loadmat(filename)
    time = [datetime.datetime(*row) for row in data["td"]]
    freq = data["fd"].ravel()
    dir = data["thetad"].ravel()
    dset = xr.DataArray(
        data=data["spec2d"] / R2D,
        coords={"time": time, attrs.FREQNAME: freq, attrs.DIRNAME: dir},
        dims=("time", attrs.FREQNAME, attrs.DIRNAME),
        name="efth",
    ).to_dataset()

    # Assign metadata
    header = data["__header__"]
    if isinstance(header, bytes):
        header = header.decode("utf-8")

    version = data["__version__"]
    if isinstance(version, bytes):
        version = version.decode("utf-8")

    dset.attrs = {"header": header, "version": version}

    # Setting standard attributes
    set_spec_attributes(dset)

    return dset



class XWavesBackendEntrypoint(BackendEntrypoint):
    """XWaves backend engine."""

    def open_dataset(
        self,
        filename_or_obj,
        *,
        drop_variables=None,
    ):
        return read_xwaves(filename_or_obj)

    def guess_can_open(self, filename_or_obj):
        return False

    description = "Open XWaves spectra files as a wavespectra dataset."

    url = "https://github.com/wavespectra/wavespectra"