Takes a cube which goes longitude 0-360 back to -180-180.

roll_cube.py

def roll_cube_e2w(cube_in, inplace=False):
    """Takes a cube which goes longitude 0-360 back to -180-180."""
    if inplace:
        cube = cube_in
    else:
        cube = cube_in.copy()
    lon = cube.coord('longitude')
    if (lon.points >= 0.).all():
        if (lon.points <= 360.).all():
            subtract = -180.
            cube.data = np.roll(cube.data,
                                len(lon.points) // 2)
        else:
            # because for regional runs, UM output
            # can have longitudes > 360
            # In this case no data roll needed
            subtract = -360.

        if lon.has_bounds():
            bounds = lon.bounds + subtract
        else:
            bounds = None
        cube.replace_coord(lon.copy(points=lon.points + subtract,
                                    bounds=bounds))
    else:
        # Nothing to do, the cube is already centered on 0 longitude
        # unless there is something wrong with longitude
        msg = ('Incorrect longitude values:'
               f'from {lon.points.min()} to {lon.points.max()}')
        assert ((lon.points >= -180.) & (lon.points <= 180.)).all(), msg
    if not inplace:
        return cube