empty features should be None

efel/pyfeatures/pyfeatures.py

@@ -291,7 +291,7 @@ def spikes_per_burst():
     burst_begin_indices = get_cpp_feature("burst_begin_indices")
     burst_end_indices = get_cpp_feature("burst_end_indices")
 
-    if burst_begin_indices is None:
+    if burst_begin_indices is None or len(burst_begin_indices) < 1:
         return None
 
     ap_per_bursts = []
@@ -304,7 +304,7 @@ def spikes_per_burst():
 def spikes_per_burst_diff():
     """Calculate the diff between the spikes in each burst and the next one"""
     spikes_per_burst_values = spikes_per_burst()
-    if spikes_per_burst_values is None:
+    if spikes_per_burst_values is None or len(spikes_per_burst_values) < 2:
         return None
 
     return spikes_per_burst_values[:-1] - spikes_per_burst_values[1:]

tests/testdata/allfeatures/expectedresults.json

@@ -435,8 +435,8 @@
     "interburst_60percent_indices": null,
     "interburst_60percent_values": null,
     "interburst_duration": null,
-    "interburst_min_indices": [],
-    "interburst_min_values": [],
+    "interburst_min_indices": null,
+    "interburst_min_values": null,
     "interburst_voltage": [
         -38.820613862535545
     ],
@@ -624,7 +624,7 @@
     "strict_burst_number": [
         1
     ],
-    "strict_interburst_voltage": [],
+    "strict_interburst_voltage": null,
     "time": [
         0.0,
         0.1,
@@ -30632,7 +30632,7 @@
     "time_to_first_spike": [
         8.000000000092427
     ],
-    "time_to_interburst_min": [],
+    "time_to_interburst_min": null,
     "time_to_last_spike": [
         1937.7999999986964
     ],
@@ -60680,7 +60680,7 @@
     "spikes_per_burst": [
         2
     ],
-    "spikes_per_burst_diff": [],
+    "spikes_per_burst_diff": null,
     "spikes_in_burst1_burst2_diff": null,
     "spikes_in_burst1_burstlast_diff": null,
     "depol_block": null,
@@ -60723,7 +60723,7 @@
     "strict_burst_mean_freq": [
         7.99041151
     ],
-    "strict_interburst_voltage": [],
+    "strict_interburst_voltage": null,
     "ADP_peak_amplitude": [
         0.0,
         2.6873666528663236,
@@ -60748,8 +60748,8 @@
         -41.12299346923828,
         -38.12341871769886
     ],
-    "interburst_min_indices": [],
-    "interburst_min_values": [],
+    "interburst_min_indices": null,
+    "interburst_min_values": null,
     "postburst_min_indices": [
         26465
     ],