Check for too high dimensions in sequences

src/oemof/solph/_plumbing.py

@@ -48,6 +48,11 @@ def sequence(iterable_or_scalar):
     10
 
     """
+    if len(np.shape(iterable_or_scalar)) > 1:
+        d = len(np.shape(iterable_or_scalar))
+        raise ValueError(
+            f"Dimension too high ({d} > 1) for {iterable_or_scalar}"
+        )
     if isinstance(iterable_or_scalar, str):
         return iterable_or_scalar
     elif isinstance(iterable_or_scalar, abc.Iterable):

tests/test_plumbing.py

@@ -7,6 +7,7 @@
 SPDX-License-Identifier: MIT
 """
 import numpy as np
+import pandas as pd
 import pytest
 
 from oemof.solph._plumbing import _FakeSequence
@@ -66,6 +67,15 @@ def test_sequence():
     assert seq_ab == "ab"
 
 
+def test_dimension_is_too_high_to_create_a_sequence():
+    df = pd.DataFrame({"epc": 5}, index=["a"])
+    with pytest.raises(ValueError, match="Dimension too high"):
+        sequence(df)
+    n2 = [[4]]
+    with pytest.raises(ValueError, match="Dimension too high"):
+        sequence(n2)
+
+
 def test_valid_sequence():
     np_array = np.array([0, 1, 2, 3, 4])
     assert valid_sequence(np_array, 5)