utils.py 文件源码

def density_slice(rast, rel=np.less_equal, threshold=1000, nodata=-9999):
    '''
    Returns a density slice from a given raster. Arguments:
        rast        A gdal.Dataset or a NumPy array
        rel         A NumPy logic function; defaults to np.less_equal
        threshold   An integer number
    '''
    # Can accept either a gdal.Dataset or numpy.array instance
    if not isinstance(rast, np.ndarray):
        rastr = rast.ReadAsArray()

    else:
        rastr = rast.copy()

    if (len(rastr.shape) > 2 and min(rastr.shape) > 1):
        raise ValueError('Expected a single-band raster array')

    return np.logical_and(
        rel(rastr, np.ones(rast.shape) * threshold),
        np.not_equal(rastr, np.ones(rast.shape) * nodata)).astype(np.int0)