From e04e1a53fd6a21506693d53f8a8519dbf4261817 Mon Sep 17 00:00:00 2001
From: Dimitris Mantas <75796651+DimitrisMantas@users.noreply.github.com>
Date: Mon, 26 Feb 2024 23:45:52 +0100
Subject: [PATCH] Implement deterministic GeoDataset (#1908)

---
 tests/datasets/test_geo.py | 15 +++++++++++++++
 torchgeo/datasets/geo.py   |  5 +++--
 2 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/tests/datasets/test_geo.py b/tests/datasets/test_geo.py
index 0e1a4ce17e3..8af3333a8c3 100644
--- a/tests/datasets/test_geo.py
+++ b/tests/datasets/test_geo.py
@@ -177,6 +177,21 @@ def test_files_property_for_virtual_files(self) -> None:
         ]
         assert len(CustomGeoDataset(paths=paths).files) == len(paths)
 
+    def test_files_property_ordered(self) -> None:
+        """Ensure that the list of files is ordered."""
+        paths = ["file://file3.tif", "file://file1.tif", "file://file2.tif"]
+        assert CustomGeoDataset(paths=paths).files == sorted(paths)
+
+    def test_files_property_deterministic(self) -> None:
+        """Ensure that the list of files is consistent regardless of their original
+        order.
+        """
+        paths1 = ["file://file3.tif", "file://file1.tif", "file://file2.tif"]
+        paths2 = ["file://file2.tif", "file://file3.tif", "file://file1.tif"]
+        assert (
+            CustomGeoDataset(paths=paths1).files == CustomGeoDataset(paths=paths2).files
+        )
+
 
 class TestRasterDataset:
     @pytest.fixture(params=zip([["R", "G", "B"], None], [True, False]))
diff --git a/torchgeo/datasets/geo.py b/torchgeo/datasets/geo.py
index 1e2382db0fe..1f1ede5890d 100644
--- a/torchgeo/datasets/geo.py
+++ b/torchgeo/datasets/geo.py
@@ -287,7 +287,7 @@ def res(self, new_res: float) -> None:
         self._res = new_res
 
     @property
-    def files(self) -> set[str]:
+    def files(self) -> list[str]:
         """A list of all files in the dataset.
 
         Returns:
@@ -316,7 +316,8 @@ def files(self) -> set[str]:
                     UserWarning,
                 )
 
-        return files
+        # Sort the output to enforce deterministic behavior.
+        return sorted(files)
 
 
 class RasterDataset(GeoDataset):