.. _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, k-permutations, and Cartesian products.
• 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.
• Derangement operations - Predicates for generating and testing derangements.
• Lexicographic stepping - Predicates for navigating permutations in lexicographic order.
• Indexed access - Predicates for direct access to permutations at specific positions.
• Counting operations - Predicates for counting permutations.
• Random selection - Predicates for randomly selecting permutations. Dedicated combinations and subsequences libraries are also available for focused APIs on those operations.

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)).