start work on CDF/SF thresholding

src/icepool/__init__.py

@@ -48,10 +48,10 @@
 
 from icepool.function import (d, z, __getattr__, coin, stochastic_round,
                               one_hot, iter_cartesian_product, from_cumulative,
-                              from_rv, min_outcome, max_outcome, consecutive,
-                              sorted_union, commonize_denominator, reduce,
-                              accumulate, map, map_function, map_and_time,
-                              map_to_pool)
+                              from_rv, highest_threshold, lowest_threshold, min_outcome, 
+                              max_outcome, consecutive, sorted_union,
+                              commonize_denominator, reduce, accumulate, map, 
+                              map_function, map_and_time, map_to_pool)
 
 from icepool.population.base import Population
 from icepool.population.die import implicit_convert_to_die, Die
@@ -147,7 +147,7 @@
     'd', 'z', 'coin', 'stochastic_round', 'one_hot', 'Outcome', 'Die',
     'Population', 'tupleize', 'vectorize', 'Vector', 'Symbols', 'Again',
     'CountsKeysView', 'CountsValuesView', 'CountsItemsView', 'from_cumulative',
-    'from_rv', 'lowest', 'highest', 'middle', 'min_outcome', 'max_outcome',
+    'from_rv', 'highest_threshold', 'lowest_threshold', 'lowest', 'highest', 'middle', 'min_outcome', 'max_outcome',
     'consecutive', 'sorted_union', 'commonize_denominator', 'reduce',
     'accumulate', 'map', 'map_function', 'map_and_time', 'map_to_pool',
     'Reroll', 'RerollType', 'Pool', 'standard_pool', 'MultisetGenerator',

src/icepool/function.py

@@ -235,6 +235,33 @@ def _iter_outcomes(
         else:
             yield arg
 
+def highest_threshold(*dice: 'icepool.Die[T]') -> 'icepool.Die[T]':
+    """Description TBD
+
+    For each outcome, the chance of the result rolling >= to that outcome is the
+    same as the highest chance among the arguments.
+    
+    Args:
+        dice: Any number of dice.
+    """
+    dice = commonize_denominator(*dice)
+    outcomes = sorted_union(*dice)
+    cumulative = [max(die.quantity('>=', outcome) for die in dice) for outcome in outcomes]
+    return from_cumulative(outcomes, cumulative, reverse=True)
+
+def lowest_threshold(*dice: 'icepool.Die[T]') -> 'icepool.Die[T]':
+    """Description TBD
+    
+    For each outcome, the chance of the result rolling <= to that outcome is the
+    same as the highest chance among the arguments.
+    
+    Args:
+        dice: Any number of dice.
+    """
+    dice = commonize_denominator(*dice)
+    outcomes = sorted_union(*dice)
+    cumulative = [max(die.quantity('<=', outcome) for die in dice) for outcome in outcomes]
+    return from_cumulative(outcomes, cumulative)
 
 @overload
 def min_outcome(arg: 'Iterable[T | icepool.Population[T]]', /) -> T:

tests/function_test.py

@@ -1,7 +1,7 @@
 import icepool
 import pytest
 
-from icepool import d4, d6, d8, d10, d12, min_outcome, max_outcome
+from icepool import d4, d6, d8, d10, d12, d20, min_outcome, max_outcome, highest_threshold, lowest_threshold
 
 
 def test_min_outcome_single_arg():
@@ -26,3 +26,17 @@ def test_max_outcome_multiple_arg():
 
 def test_max_outcome_bare_outcome():
     assert max_outcome(d6, d8, 10, 2) == 10
+
+def test_highest_threshold():
+    result = highest_threshold(3 @ d6, d20)
+    for outcome in range(1, 21):
+        assert result.probability('>=', outcome) == max(
+            (3 @ d6).probability('>=', outcome),
+            d20.probability('>=', outcome))
+
+def test_lowest_threshold():
+    result = lowest_threshold(3 @ d6, d20)
+    for outcome in range(1, 21):
+        assert result.probability('<=', outcome) == max(
+            (3 @ d6).probability('<=', outcome),
+            d20.probability('<=', outcome))