Source code for pycif.plugins.domains.dummy.read_domain

import numpy as np

from logging import info




def read_grid(domain, **kwargs):
    """Read the dummy Cartesian domain from text files or fall back to ``create_domain``.

    Loads 1-D coordinate arrays from ``domain.filelon`` and ``domain.filelat``,
    derives half-step corners, and builds 2-D meshgrids.  Cell areas are
    computed as the Cartesian product of zonal and meridional cell sizes.

    If the files cannot be read (``IOError``) or the attributes are absent
    (``AttributeError``), delegates to ``domain.create_domain()`` to build
    the grid from YAML parameters.

    Sets on *domain*: ``nlon``, ``nlat``, ``zlon``, ``zlat``, ``zlonc``,
    ``zlatc``, ``areas``, ``projection``.

    Args:
        domain: dummy domain plugin instance.
        **kwargs: unused.
    """

    # Tries open filelon, filelat
    try:
        zlon = np.loadtxt(domain.filelon)
        zlat = np.loadtxt(domain.filelat)

        nlon = zlon.size
        nlat = zlat.size

        # Corner coordinates
        dlon = np.ptp(zlon) / (nlon - 1) / 2.0
        zlonc = zlon - dlon
        zlonc = np.append(zlonc, zlonc[-1] + 2 * dlon)

        dlat = np.ptp(zlat) / (nlat - 1) / 2.0
        zlatc = zlat - dlat
        zlatc = np.append(zlatc, zlatc[-1] + 2 * dlat)

        # Meshgrids
        zlon, zlat = np.meshgrid(zlon, zlat)
        zlonc, zlatc = np.meshgrid(zlonc, zlatc)

        # Saving information to domain attributes
        domain.nlon = nlon
        domain.nlat = nlat
        domain.zlon = zlon
        domain.zlat = zlat
        domain.zlonc = zlonc
        domain.zlatc = zlatc

    except (IOError, AttributeError):
        info(
            "Couldn't read longitudes and latitudes.\n"
            "Make them from given coordinates"
        )
        domain.create_domain()

    # Compute areas in m2
    domain.areas = (
        np.diff(domain.zlatc, axis=0)[:, :-1]
        * np.diff(domain.zlonc, axis=1)[:-1]
    )

    # Projection not as GPS
    domain.projection = "xy"