format

src/carousel/__init__.py

@@ -5,6 +5,7 @@ import polars.selectors as pls
 
 import itertools as it
 
+
 def rank_to_pref(R):
     """Converts a ranking to a preference."""
     id_col_name = R.select(pls.by_index(0)).to_series().name
@@ -66,53 +67,74 @@ def check_valid_rank(R):
     ).get_column("ties")[0]
     return not ties
 
+
 def check_valid_match(match, applicants, reviewers):
     # TODO
     pass
 
+
 def check_valid_assgn(assgn, applicants, reviewers):
     # TODO
     pass
 
+
 def get_rank(ranking, ranker, rankee):
     idx = ranking.select(pl.arg_where(pl.col("") == rankee)).item()
     return ranking[ranker][idx]
 
-def check_unstable(match, applicant_ranking, reviewer_ranking):
-    applicants = applicant_ranking.columns[1:] # assume unique applicants
-    for a, b in it.combinations(applicants, 2):
-        A = match.select(c for c in match.iter_columns() if a in c).to_series().name # the reviewer a is matched to
-        B = match.select(c for c in match.iter_columns() if b in c).to_series().name # the reviewer b is matched to
 
-        b_prefers_A = get_rank(applicant_ranking, b, A) < get_rank(applicant_ranking, b, B)
+def check_unstable(match, applicant_ranking, reviewer_ranking):
-        A_prefers_b = get_rank(reviewer_ranking, A, b) < get_rank(reviewer_ranking, A, a)
+    applicants = applicant_ranking.columns[1:]  # assume unique applicants
+    for a, b in it.combinations(applicants, 2):
+        A = (
+            match.select(c for c in match.iter_columns() if a in c).to_series().name
+        )  # the reviewer a is matched to
+        B = (
+            match.select(c for c in match.iter_columns() if b in c).to_series().name
+        )  # the reviewer b is matched to
+
+        b_prefers_A = get_rank(applicant_ranking, b, A) < get_rank(
+            applicant_ranking, b, B
+        )
+        A_prefers_b = get_rank(reviewer_ranking, A, b) < get_rank(
+            reviewer_ranking, A, a
+        )
         if b_prefers_A and A_prefers_b:
             return True
 
         # or
-        a_prefers_B = get_rank(applicant_ranking, a, B) < get_rank(applicant_ranking, a, A)
+        a_prefers_B = get_rank(applicant_ranking, a, B) < get_rank(
-        B_prefers_a = get_rank(reviewer_ranking, B, a) < get_rank(reviewer_ranking, B, b)
+            applicant_ranking, a, A
+        )
+        B_prefers_a = get_rank(reviewer_ranking, B, a) < get_rank(
+            reviewer_ranking, B, b
+        )
         if a_prefers_B and B_prefers_a:
             return True
     # else
     return False
 
+
 def check_stable(*args, **kwargs):
     return not check_unstable(*args, **kwargs)
 
+
 def deferred_acceptance(A, R):
     """Find the Gale-Shapley deferred-acceptance stable matching for preferences A, R."""
     # TODO - the core algorithm!
     pass
 
+
 def assgn_to_match(assgn):
     # TODO
     pass
 
+
 def match_to_assgn(match):
     # TODO
     pass
 
+
 def main() -> None:
     rich.print("Hello from [italic red]carousel[/italic red]!")
 

test/galeshapley_test.py

@@ -82,15 +82,48 @@ def test_prefs_tofrom_ranks(P):
 
 
 def test_eg3_unstable():
-    applicant_rankings = pl.DataFrame({"": ["A", "B", "C", "D"], "a": [1, 2, 3, 4], "b": [1, 4, 3, 2], "c": [2, 1, 3, 4], "d": [4, 2, 3, 1]})
+    applicant_rankings = pl.DataFrame(
-    reviewer_rankings = pl.DataFrame({"": ["a", "b", "c", "d"], "A": [3, 4, 2, 1], "B": [3, 1, 4, 2], "C": [2, 3, 4, 1], "D": [3, 2, 1, 4] })
+        {
-    match = pl.DataFrame({"A" : ["a"], "B": ["b"], "C": ["c"], "D": ["d"]})
+            "": ["A", "B", "C", "D"],
+            "a": [1, 2, 3, 4],
+            "b": [1, 4, 3, 2],
+            "c": [2, 1, 3, 4],
+            "d": [4, 2, 3, 1],
+        }
+    )
+    reviewer_rankings = pl.DataFrame(
+        {
+            "": ["a", "b", "c", "d"],
+            "A": [3, 4, 2, 1],
+            "B": [3, 1, 4, 2],
+            "C": [2, 3, 4, 1],
+            "D": [3, 2, 1, 4],
+        }
+    )
+    match = pl.DataFrame({"A": ["a"], "B": ["b"], "C": ["c"], "D": ["d"]})
 
     assert crsl.check_unstable(match, applicant_rankings, reviewer_rankings)
 
+
 def test_eg3_isstable():
-    applicant_rankings = pl.DataFrame({"": ["A", "B", "C", "D"], "a": [1, 2, 3, 4], "b": [1, 4, 3, 2], "c": [2, 1, 3, 4], "d": [4, 2, 3, 1]})
+    applicant_rankings = pl.DataFrame(
-    reviewer_rankings = pl.DataFrame({"": ["a", "b", "c", "d"], "A": [3, 4, 2, 1], "B": [3, 1, 4, 2], "C": [2, 3, 4, 1], "D": [3, 2, 1, 4] })
+        {
-    match = pl.DataFrame({"A" : ["c"], "B": ["d"], "C": ["a"], "D": ["b"]})
+            "": ["A", "B", "C", "D"],
+            "a": [1, 2, 3, 4],
+            "b": [1, 4, 3, 2],
+            "c": [2, 1, 3, 4],
+            "d": [4, 2, 3, 1],
+        }
+    )
+    reviewer_rankings = pl.DataFrame(
+        {
+            "": ["a", "b", "c", "d"],
+            "A": [3, 4, 2, 1],
+            "B": [3, 1, 4, 2],
+            "C": [2, 3, 4, 1],
+            "D": [3, 2, 1, 4],
+        }
+    )
+    match = pl.DataFrame({"A": ["c"], "B": ["d"], "C": ["a"], "D": ["b"]})
 
     assert crsl.check_stable(match, applicant_rankings, reviewer_rankings)