.. _library_permutations:

permutations

This library provides predicates for generating and querying permutations over lists. The following categories of predicates are provided:

• Generation operations - Predicates for generating permutations and k-permutations.
• Ordering variants - Predicates that support an additional order argument (default, lexicographic, or shortlex) for controlling output order.
• Distinct-value generation - Predicates for generating permutations while deduplicating equal-valued results.
• Lexicographic stepping - Predicates for navigating permutations in lexicographic order.
• Indexed access - Predicates for direct access to permutations at specific positions, including distinct permutations.
• Counting operations - Predicates for counting permutations and distinct permutations.
• Random selection - Predicates for randomly selecting and sampling permutations and distinct permutations.

  Dedicated arrangements, cartesian_products, combinations, derangements, multisets, partitions, and subsequences libraries are also available for focused APIs on related operations. The arrangements library is the repetition-allowed counterpart to this library.

API documentation

Open the `../../apis/library_index.html#permutations <../../apis/library_index.html#permutations>`__ link in a web browser.

Loading

To load all entities in this library, load the loader.lgt file:

::

| ?- logtalk_load(permutations(loader)).

Testing

To test this library predicates, load the tester.lgt file:

::

| ?- logtalk_load(permutations(tester)).