Fix FID metric for scipy >= 1.18: sqrtm no longer accepts disp

monai/metrics/fid.py

@@ -82,7 +82,7 @@ def _cov(input_data: torch.Tensor, rowvar: bool = True) -> torch.Tensor:
 
 def _sqrtm(input_data: torch.Tensor) -> torch.Tensor:
     """Compute the square root of a matrix."""
-    scipy_res, _ = scipy.linalg.sqrtm(input_data.detach().cpu().numpy().astype(np.float64), disp=False)
+    scipy_res = scipy.linalg.sqrtm(input_data.detach().cpu().numpy().astype(np.float64))
     return torch.from_numpy(scipy_res)
 
 

tests/metrics/test_compute_fid_metric.py

@@ -17,6 +17,7 @@
 import torch
 
 from monai.metrics import FIDMetric
+from monai.metrics.fid import _sqrtm
 from monai.utils import optional_import
 
 _, has_scipy = optional_import("scipy")
@@ -25,6 +26,12 @@
 @unittest.skipUnless(has_scipy, "Requires scipy")
 class TestFIDMetric(unittest.TestCase):
 
+    def test_sqrtm_returns_tensor(self):
+        """``scipy.linalg.sqrtm`` dropped its ``disp`` argument, and with it the 2-tuple return."""
+        result = _sqrtm(torch.tensor([[4.0, 0.0], [0.0, 9.0]], dtype=torch.float64))
+        self.assertIsInstance(result, torch.Tensor)
+        np.testing.assert_allclose(result.cpu().numpy(), np.array([[2.0, 0.0], [0.0, 3.0]]), atol=1e-6)
+
     def test_results(self):
         x = torch.Tensor([[1, 2], [1, 2], [1, 2]])
         y = torch.Tensor([[2, 2], [1, 2], [1, 2]])