Source code for pycif.plugins.datastreams.fields.lmdz_chemfield.read

import xarray as xr
from .....utils.hdf5 import _hdf5_lock




def read(
        self, name, varnames, dates, files,
        interpol_flx=False, comp_type=None,
        ddi=None,
        **kwargs
):
    """Read LMDz chemical field data and load it into a pyCIF DataArray.

    Opens each distinct file in ``files`` once, selects the day index
    (relative to the file's month, computed from ``ddi``) for each
    requested date, concatenates the selected time steps along
    ``time_counter``, renames dimensions to pyCIF's
    ``(time, lev, lat, lon)`` convention, drops non-time coordinates, and
    duplicates the first longitude column to close LMDZ's cyclic grid.

    Args:
        self: The field/tracer Plugin.
        name: Name of the component; used as fallback variable name.
        varnames: Name of the variable to read; if empty, ``name`` is used
            instead.
        dates: List of date entries to extract, matching ``files``.
        files: List of files matching ``dates``; each distinct file is
            opened only once.
        interpol_flx: Unused.
        comp_type: Unused.
        ddi: Reference date used to compute each date's day-of-month index
            within its file.
        **kwargs: Unused.

    Returns:
        xarray.DataArray: A 4-dimensional ``(time, lev, lat, lon)`` array.
    """
    varnames = varnames if varnames else name

    da_list = []
    file_ref = ""
    for dd, file_path in zip(dates, files):
        if file_path != file_ref:
            file_ref = file_path
            with _hdf5_lock:
                with xr.open_dataset(file_path) as ds:
                    da = ds[varnames]

        day_index = (dd[0] - ddi).days
        da_list.append(da.isel(time_counter=[day_index]))

    xmod = xr.concat(da_list, dim='time_counter')
    xmod = xmod.rename({'time_counter': "time", 'presnivs': "lev"})

    # Dropping coordinates
    for coord_name in xmod.coords:
        if coord_name != 'time':
            xmod = xmod.drop(coord_name)

    # Reordering dimensions
    xmod = xmod.transpose('time', 'lev', 'lat', 'lon')

    # Loop longitude coordinate to match LMDZ grid
    index = list(range(xmod.shape[3])) + [0]
    xmod = xmod.isel(lon=index)

    return xmod