Function posify_index

dask/array/slicing.py:651–676

Flip negative indices around to positive ones >>> posify_index(10, 3) 3 >>> posify_index(10, -3) 7 >>> posify_index(10, [3, -3]) array([3, 7]) >>> posify_index((10, 20), (3, -3)) (3, 17) >>> posify_index((10, 20), (3, [3, 4, -3])) # doctest: +NORMALIZE_WHITESPA

(shape, ind)

def posify_index(shape, ind):
    """Flip negative indices around to positive ones

    >>> posify_index(10, 3)
    3
    >>> posify_index(10, -3)
    7
    >>> posify_index(10, [3, -3])
    array([3, 7])

    >>> posify_index((10, 20), (3, -3))
    (3, 17)
    >>> posify_index((10, 20), (3, [3, 4, -3]))  # doctest: +NORMALIZE_WHITESPACE
    (3, array([ 3,  4, 17]))
    """
    if isinstance(ind, tuple):
        return tuple(map(posify_index, shape, ind))
    if isinstance(ind, Integral):
        if ind < 0 and not math.isnan(shape):
            return ind + shape
        else:
            return ind
    if isinstance(ind, (np.ndarray, list)) and not math.isnan(shape):
        ind = np.asanyarray(ind)
        return np.where(ind < 0, ind + shape, ind)
    return ind


@memoize