opt_einsum.paths.optimal¶
-
opt_einsum.paths.
optimal
(input_sets, output_set, idx_dict, memory_limit)[source]¶ Computes all possible pair contractions, sieves the results based on
memory_limit
and returns the lowest cost path. This algorithm scales factorial with respect to the elements in the listinput_sets
.Parameters: - input_sets (list) – List of sets that represent the lhs side of the einsum subscript
- output_set (set) – Set that represents the rhs side of the overall einsum subscript
- idx_dict (dictionary) – Dictionary of index sizes
- memory_limit (int) – The maximum number of elements in a temporary array
Returns: path – The optimal contraction order within the memory limit constraint.
Return type: Examples
>>> isets = [set('abd'), set('ac'), set('bdc')] >>> oset = set('') >>> idx_sizes = {'a': 1, 'b':2, 'c':3, 'd':4} >>> optimal(isets, oset, idx_sizes, 5000) [(0, 2), (0, 1)]