fix: empty lists were not serialized property, but send as empty ndarray

ipyvolume/serialize.py

@@ -154,8 +154,11 @@ def array_sequence_to_binary_or_json(ar, obj=None):
 		pass
 	if isinstance(element, string_types):
 		return array_to_json(ar)
-	if dimension == 0: # scalars are passed as is (json)
-		return element
+	if dimension == 0: # scalars are passed as is (json), empty lists as well
+		if isinstance(element, np.ndarray): # must be an empty list
+			return []
+		else:
+			return element
 	if isinstance(ar, (list, tuple, np.ndarray)): # ok, at least 1d
 		if isinstance(ar[0], (list, tuple, np.ndarray)): # ok, 2d
 			return [array_to_binary(ar[k]) for k in range(len(ar))]

ipyvolume/test_all.py

@@ -4,6 +4,7 @@
 import ipyvolume.examples
 import ipyvolume.datasets
 import ipyvolume.utils
+import ipyvolume.serialize
 import numpy as np
 import os
 import shutil
@@ -16,6 +17,19 @@
     shutil.rmtree("tmp")
 os.makedirs("tmp")
 
+def test_serialize():
+    assert ipyvolume.serialize.array_sequence_to_binary_or_json(1) == 1
+    assert ipyvolume.serialize.array_sequence_to_binary_or_json([]) == []
+    empty_array = np.array([])
+    assert ipyvolume.serialize.array_sequence_to_binary_or_json(empty_array) == []
+    assert type(ipyvolume.serialize.array_sequence_to_binary_or_json(empty_array)) == list
+
+    value = np.asarray(5)
+    assert ipyvolume.serialize.array_sequence_to_binary_or_json(value) == 5
+
+    value = np.asarray(5)
+    assert ipyvolume.serialize.array_sequence_to_binary_or_json(value) == 5
+
 def test_figure():
     f1 = p3.figure()
     f2 = p3.figure(2)