Function fractional_slice

dask/layers.py:323–360

>>> fractional_slice(('x', 5.1), {0: 2}) ( , ('x', 5), (slice(-2, None, None),)) >>> fractional_slice(('x', 3, 5.1), {0: 2, 1: 3}) ( , ('x', 3, 5), (slice(None, None, None), slice(-3, None, None))) >>> fractional_slice(('x',

(task, axes)

def fractional_slice(task, axes):
    """

    >>> fractional_slice(('x', 5.1), {0: 2})
    (<built-in function getitem>, ('x', 5), (slice(-2, None, None),))

    >>> fractional_slice(('x', 3, 5.1), {0: 2, 1: 3})
    (<built-in function getitem>, ('x', 3, 5), (slice(None, None, None), slice(-3, None, None)))

    >>> fractional_slice(('x', 2.9, 5.1), {0: 2, 1: 3})
    (<built-in function getitem>, ('x', 3, 5), (slice(0, 2, None), slice(-3, None, None)))
    """
    rounded = (task[0],) + tuple(int(round(i)) for i in task[1:])

    index = []
    for i, (t, r) in enumerate(zip(task[1:], rounded[1:])):
        depth = axes.get(i, 0)
        if isinstance(depth, tuple):
            left_depth = depth[0]
            right_depth = depth[1]
        else:
            left_depth = depth
            right_depth = depth

        if t == r:
            index.append(slice(None, None, None))
        elif t < r and right_depth:
            index.append(slice(0, right_depth))
        elif t > r and left_depth:
            index.append(slice(-left_depth, None))
        else:
            return False
    index = tuple(index)

    if all(ind == slice(None, None, None) for ind in index):
        return task
    else:
        return (operator.getitem, rounded, index)


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