Forest snapshot tests

tests/conftest.py

@@ -1,9 +1,11 @@
+import hashlib
 import os
 
 from syndiffix.common import *
 from syndiffix.counters import UniqueAidCountersFactory
 from syndiffix.forest import *
 from syndiffix.microdata import apply_convertors, get_convertor
+from syndiffix.tree import Branch, Leaf, Node
 
 SALT = bytes([])
 NOISELESS_SUPPRESSION = SuppressionParams(layer_sd=0.0)
@@ -48,3 +50,33 @@ def load_forest(
     current_dir = os.path.dirname(os.path.abspath(__file__))
     data_df = _load_csv(os.path.join(current_dir, "data", filename), columns)
     return create_forest(data_df, anon_params=anon_params, bucketization_params=bucketization_params)
+
+
+# Forest hashing
+
+
+def _fstr(num: float) -> str:
+    return str(int(num)) if num.is_integer() else str(num)
+
+
+def _ranges_str(node: Node) -> str:
+    intervals = [
+        f"[{_fstr(round(interval.min, 5))},{_fstr(round(interval.max, 5))}]" for interval in node.snapped_intervals
+    ]
+    return ", ".join(intervals)
+
+
+def hash_tree(node: Node) -> str:
+    outstr = ""
+
+    outstr += "Leaf;" if isinstance(node, Leaf) else "Branch;"
+    outstr += f"Count:{node.noisy_count()};"
+    outstr += f"Ranges:{_ranges_str(node)};"
+
+    if isinstance(node, Branch):
+        outstr += "Children:"
+        for key, child in sorted(node.children.items()):
+            child_hash = hash_tree(child)
+            outstr += f"Id:{key};Hash:{child_hash};"
+
+    return hashlib.sha1(outstr.encode("utf-8")).hexdigest()

tests/test_forest.py

@@ -141,3 +141,27 @@ def test_depth_limiting() -> None:
     forest = create_forest(DataFrame(data, columns=["col"]), bucketization_params=zero_depth_params)
     tree = forest.get_tree((ColumnId(0),))
     assert isinstance(tree, Leaf)
+
+
+def test_taxi_snapshot() -> None:
+    forest = load_forest(
+        "taxi-1000.csv",
+        columns=["pickup_longitude", "pickup_latitude", "fare_amount", "rate_code", "passenger_count"],
+        anon_params=NOISELESS_PARAMS,
+    )
+
+    def get_hash(*cols: list[int]) -> str:
+        return hash_tree(forest.get_tree(tuple(ColumnId(col) for col in cols)))
+
+    # Single dimensions
+    assert get_hash(0) == "c54e1fcd3aeda4e2efaa8ac178f5dfe7d12d8cc2"
+    assert get_hash(1) == "8ab7f27328f922965b89fc0f894eab0ca474c986"
+    assert get_hash(2) == "0460917ff0942a43f9e28cbdc132dd3861995c82"
+    assert get_hash(3) == "cfa83a32d3eea908b4bb33d858e7a8786952b739"
+    assert get_hash(4) == "f41bc89f0e683e4ac65421b5681aa48fb1ed4456"
+
+    # Higher dimensions
+    assert get_hash(0, 1) == "daa2f4af52460728af6276fc5664d186f6a4df9b"
+    assert get_hash(0, 1, 2) == "55b1cf65c256545b3c1da970cc9c2083a87c2e97"
+    assert get_hash(0, 1, 2, 3) == "12a5ac07bf3d98501378360deb8505d90a791c32"
+    assert get_hash(0, 1, 2, 3, 4) == "bd75e1cdfd8957dd45a1f61ff6cc5a1e7254ee99"