From f6796e4e0a7b8f3165ad8e9cd0a6a26746af89bc Mon Sep 17 00:00:00 2001
From: Sam Evans <47793072+Sevans711@users.noreply.github.com>
Date: Tue, 10 Nov 2026 14:21:04 -0500
Subject: [PATCH] fix: Grid.__eq__ must check lon AND lat, not "OR"

---
 test/grid/grid/test_core.py | 17 +++++++++++++++++
 uxarray/grid/grid.py        |  7 +++----
 2 files changed, 20 insertions(+), 4 deletions(-)

diff --git a/test/grid/grid/test_core.py b/test/grid/grid/test_core.py
index da5882bea..cc178390b 100644
--- a/test/grid/grid/test_core.py
+++ b/test/grid/grid/test_core.py
@@ -77,6 +77,23 @@ def test_operators_ne(gridpath):
 
     assert grid_mpas != grid_scrip
 
+    # Regression test for #1881: == must check lon AND lat, not just one or the other.
+    # construct some grids with same connectivity, and same lon or same lat, but not both.
+    lonA = [0, 10, 20, 30]
+    lonB = [30, 40, 50, 60]
+    lat0 = [0, 0, 10, 10]
+    lat1 = [30, 30, 40, 40]
+    conn = [[0,1,2],[1,2,3]]
+    gridA0 = ux.Grid.from_topology(node_lon=lonA, node_lat=lat0, face_node_connectivity=conn)
+    gridA1 = ux.Grid.from_topology(node_lon=lonA, node_lat=lat1, face_node_connectivity=conn)
+    gridB0 = ux.Grid.from_topology(node_lon=lonB, node_lat=lat0, face_node_connectivity=conn)
+    gridB1 = ux.Grid.from_topology(node_lon=lonB, node_lat=lat1, face_node_connectivity=conn)
+
+    assert gridA0 != gridA1
+    assert gridA0 != gridB0
+    assert gridA1 != gridB1
+    assert gridB0 != gridB1
+
 
 def test_grid_properties(gridpath):
     """Tests to see if accessing variables through set properties is equal to using the dict."""
diff --git a/uxarray/grid/grid.py b/uxarray/grid/grid.py
index 6aa34fbee..1be9f0ed9 100644
--- a/uxarray/grid/grid.py
+++ b/uxarray/grid/grid.py
@@ -814,11 +814,10 @@ def __eq__(self, other) -> bool:
         if self.source_grid_spec != other.source_grid_spec:
             return False
 
-        if not (
-            self.node_lon.equals(other.node_lon) or self.node_lat.equals(other.node_lat)
-        ):
+        if not self.node_lon.equals(other.node_lon):
+            return False
+        if not self.node_lat.equals(other.node_lat):
             return False
-
         if not self.face_node_connectivity.equals(other.face_node_connectivity):
             return False