grib2io.utils.spatial

 1import numpy as np
 2
 3
 4def snap_to_nearest_cell_center(grid_lats, grid_lons, point_lat, point_lon):
 5    """
 6    Snap the given point lat/lon to the nearest grid cell center.
 7
 8    Parameters
 9    ----------
10    grid_lats
11        The latitude values for each cell in the grid.
12    grid_lons
13        The longitude values for each cell in the grid.
14    point_lat
15        Latitude of point to snap.
16    point_lon
17        Longitude of point to snap.
18
19    Returns
20    -------
21    lat
22        Latitude snapped to nearest cell center.
23    lon
24        Longitude snapped to nearest cell center.
25    """
26    snap_lat = np.abs(grid_lats - point_lat)
27    snap_lon = np.abs(grid_lons - point_lon)
28    max_idx = np.maximum(snap_lat, snap_lon)
29    j, i = np.where(max_idx == np.min(max_idx))
30    return np.array(grid_lats[j, i])[0], np.array(grid_lons[j, i])[0]
31
32
33def verify_lat_lon_bounds(lats, lons):
34    """
35    Verify that the given latitude and longitude bounds are valid.
36
37    Parameters
38    ----------
39    lats
40        Latitude bounds.
41    lons
42        Longitude bounds.
43
44    Returns
45    -------
46    None
47    """
48    if lats is not None:
49        if len(lats) != 2:
50            raise ValueError(
51                f"The `lats` keyword should supply a two-item tuple or list of (southern lat, northern lat) boundaries instead of '{lats}'."
52            )
53        if lats[0] < -90 or lats[1] > 90:
54            raise ValueError(
55                f"The southern latitude boundary '{lats[0]}' and northern latitude boundary '{lats[1]}' must be between -90 and 90 degrees."
56            )
57        if lats[0] > lats[1]:
58            raise ValueError(f"The southern latitude boundary '{lats[0]}' must be less than the northern latitude boundary '{lats[1]}'")
59    if lons is not None:
60        if len(lons) != 2:
61            raise ValueError(
62                f"The `lons` keyword should supply a two-item tuple or list of (western lon, eastern lon) boundaries instead of '{lons}'."
63            )
64        if lons[0] > lons[1]:
65            raise ValueError(f"The western longitude boundary '{lons[0]}' must be less than the eastern longitude boundary '{lons[1]}'")