Bugfix for to_numpy

Author: marvinpfoertner

src/probnum/backend/_core/_jax.py

@@ -61,6 +61,9 @@ def is_floating_dtype(dtype) -> bool:
 
 
 def to_numpy(*arrays: jax.numpy.ndarray) -> Tuple[np.ndarray, ...]:
+    if len(arrays) == 1:
+        return np.array(arrays[0])
+
     return tuple(np.array(arr) for arr in arrays)
 
 

src/probnum/backend/_core/_numpy.py

@@ -58,6 +58,9 @@ def is_floating_dtype(dtype) -> bool:
 
 
 def to_numpy(*arrays: np.ndarray) -> Tuple[np.ndarray, ...]:
+    if len(arrays) == 1:
+        return arrays[0]
+
     return tuple(arrays)
 
 

src/probnum/backend/_core/_torch.py

@@ -158,6 +158,9 @@ def cast(a: torch.Tensor, dtype=None, casting="unsafe", copy=None):
 
 
 def to_numpy(*arrays: torch.Tensor) -> Tuple[np.ndarray, ...]:
+    if len(arrays) == 1:
+        return arrays[0].cpu().detach().numpy()
+
     return tuple(arr.cpu().detach().numpy() for arr in arrays)