From 3e3564d0613c5710a19aaaf74ce36b35a98282dd Mon Sep 17 00:00:00 2001
From: Sam Morley <41870650+inakleinbottle@users.noreply.github.com>
Date: Mon, 16 Dec 2024 10:47:09 +0000
Subject: [PATCH] Fix infinite loop if support not specified (#187)

* Add tests for signature equivariance of tree-like paths

Introduces three new tests to validate the equivariance property of signatures for tree-like paths. Ensures consistency between original paths and their pruned representations using `esig_stream2sig`. These additions strengthen coverage for stream behavior in edge cases.

* Adjust effective support handling in LieIncrementStream

Replaced right_unbounded interval creation with direct initialization of `effective_support`. Added fallback to `effective_support` when `md.support` is not provided, ensuring proper restriction behavior.
---
 roughpy/src/streams/lie_increment_stream.cpp | 11 +++-
 tests/streams/test_lie_increment_path.py     | 58 ++++++++++++++++++++
 2 files changed, 66 insertions(+), 3 deletions(-)

diff --git a/roughpy/src/streams/lie_increment_stream.cpp b/roughpy/src/streams/lie_increment_stream.cpp
index d3dfb2e1d..817e76d45 100644
--- a/roughpy/src/streams/lie_increment_stream.cpp
+++ b/roughpy/src/streams/lie_increment_stream.cpp
@@ -114,8 +114,7 @@ static py::object lie_increment_stream_from_increments(py::object data, py::kwar
 
     dimn_t num_increments = ks_stream.row_count();
 
-    auto effective_support
-            = intervals::RealInterval::right_unbounded(0.0, md.interval_type);
+    intervals::RealInterval effective_support (0.0, 1.0, md.interval_type);
 
     if (kwargs.contains("indices")) {
         auto indices_arg = kwargs_pop(kwargs, "indices");
@@ -232,7 +231,13 @@ static py::object lie_increment_stream_from_increments(py::object data, py::kwar
              *md.resolution},
             md.schema
     ));
-    if (md.support) { result.restrict_to(*md.support); }
+
+    if (md.support) {
+        result.restrict_to(*md.support);
+    }
+    else {
+        result.restrict_to(effective_support);
+    }
 
     return py::reinterpret_steal<py::object>(
             python::RPyStream_FromStream(std::move(result))
diff --git a/tests/streams/test_lie_increment_path.py b/tests/streams/test_lie_increment_path.py
index 58ea1ae0a..efd7fbf28 100644
--- a/tests/streams/test_lie_increment_path.py
+++ b/tests/streams/test_lie_increment_path.py
@@ -411,3 +411,61 @@ def test_construct_sequence_of_lies():
     lsig = stream.log_signature(rp.RealInterval(0, 1))
 
     assert lsig == seq[0], f"{lsig} != {seq[0]}"
+
+
+def esig_stream2sig(array, depth):
+    no_pts, width = array.shape
+    ctx = rp.get_context(width=width, depth=depth, coeffs=rp.DPReal)
+
+    increments = np.diff(array, axis=0)
+
+    stream = rp.LieIncrementStream.from_increments(increments, ctx=ctx)
+
+    return stream.signature()
+
+
+def test_equivariance_esig_treelike1():
+
+    tree_like = np.array([
+            [0.0, 0],
+            [1, 0],
+            [1, 1],
+            [1, 0],
+            [2, 0],
+            [3, 1],
+            [2, 2],
+            [1, 1],
+            [2, 2],
+            [1, 3],
+            [2, 2],
+            [3, 3],
+            [2, 2],
+            [3, 1],
+            [4, 1],
+            [3, 1],
+            [2, 0],
+            [2, -1],
+            [2, 0],
+            [1, 0],
+            [1, -1],
+            [1, 0],
+            [0, 0],
+        ], dtype=np.float64)
+
+    pruned = np.array([[0.0, 0.0]], dtype=np.float64)
+
+    assert_array_almost_equal(esig_stream2sig(tree_like, 2), esig_stream2sig(pruned, 2))
+
+
+def test_equivariance_esig_treelike2():
+
+    tree_like = np.array([[0.0, 0], [1, 3], [0, 0], [1, 5], [2, 5], [1, 5], [0, 6], [1, 5], [0, 0]], dtype=np.float64)
+    pruned = np.array([[0., 0.]], dtype=np.float64)
+
+    assert_array_almost_equal(esig_stream2sig(tree_like, 2), esig_stream2sig(pruned, 2))
+
+def test_equivariance_esig_treelike3():
+    tree_like = np.array([[0.0, 0], [1, 1], [3, 1], [2, 1], [1, 1], [2, 0]], dtype=np.float64)
+    pruned = np.array([[0., 0.], [1. ,1.], [2., 0]], dtype=np.float64)
+
+    assert_array_almost_equal(esig_stream2sig(tree_like, 2), esig_stream2sig(pruned, 2))
\ No newline at end of file