Rating difficulty

rate(puzzle) solves the puzzle the way a person would. At each step it uses the simplest technique that makes progress. The hardest technique it needs sets the level.

>>> rating = pp.rate(pp.generate("sudoku", difficulty="hard", seed=7).puzzle)
>>> rating.level
<Difficulty.HARD: 'hard'>
>>> rating.techniques
('claiming', 'hidden_pair', 'hidden_single', 'naked_pair', 'naked_single', 'pointing')

rate returns a Rating:

Field	Value
level	The Difficulty: easy, medium, hard or expert
techniques	The techniques used, by name
steps	The number of deductions
score	The total size of the step explanations. It changes between rater versions and does not measure solving time.
rater_version	The genre’s rater version

The technique names are listed on each genre page under Techniques. Puzzles from generate already carry their rating in Generated.rating.

rate raises UnratedPuzzleError when the puzzle has one solution but the supported techniques cannot finish it. It raises NoSolutionError or MultipleSolutionsError like solve.

pp.Difficulty values compare equal to their names, so rating.level == "hard" works. How puzzles are rated describes the levels and the method in full.