fix: ensure compat with pandas item selection and numpy >= 2.0 (#434)

* fix: ensure compat with pandas item selection and numpy >= 2.0

* revert unneeded condition

Author: FabianHofmann

doc/release_notes.rst

@@ -4,6 +4,10 @@ Release Notes
 Upcoming Version
 ----------------
 
+**Bug Fixes**
+
+* Fix the multiplication with of zero dimensional numpy arrays with linopy objects. This is mainly affecting operations where single numerical items from  pandas objects are selected and used for multiplication.
+
 Version 0.5.1
 --------------
 

linopy/common.py

@@ -205,6 +205,10 @@ def numpy_to_dataarray(
         DataArray:
             The converted DataArray.
     """
+    # fallback case for zero dim arrays
+    if arr.ndim == 0:
+        return DataArray(arr.item(), coords=coords, dims=dims, **kwargs)
+
     ndim = max(arr.ndim, 0 if coords is None else len(coords))
     if isinstance(dims, (Iterable, Sequence)):
         dims = list(dims)

test/test_linear_expression.py

@@ -199,6 +199,9 @@ def test_linear_expression_with_multiplication(x: Variable) -> None:
     expr = np.array([1, 2]) * x
     assert isinstance(expr, LinearExpression)
 
+    expr = np.array(1) * x
+    assert isinstance(expr, LinearExpression)
+
     expr = xr.DataArray(np.array([[1, 2], [2, 3]])) * x
     assert isinstance(expr, LinearExpression)