def decompose()

in utils/utils.py [0:0]

• 17 lines of code
• 4 McCabe index (conditional complexity)

    def decompose(index, shape, stride=None):
        ''' 
        This function solve the math problem below:
            There is an equation: 
                index = sum(idx[i] * stride[i])
            And given the value of index, stride.
            Return the idx.
        This function will used to get the pp/dp/pp_rank
        from group_index and rank_in_group.
        '''
        if stride is None:
            stride = prefix_product(shape)
        idx = [(index // d) % s for s, d in zip(shape, stride)]
        # stride is a prefix_product result. And the value of stride[-1]
        # is not used.
        assert (
            sum([x * y for x, y in zip(idx, stride[:-1])]) == index
        ), "idx {} with shape {} mismatch the return idx {}".format(index, shape, idx)
        return idx