fix(core): added a json converter class in json_encoder.py to pyscan/…

…general. This is now implemented in the save_metadata method of abstract_experiment.py which enables numpy values to be used as data inputs before saving. The converter changes the numpy values to standard python values and no longer throws the same type error as before.

pyscan/general/json_encoder.py

@@ -0,0 +1,17 @@
+import json
+import numpy as np
+
+
+class NumpyEncoder(json.JSONEncoder):
+    """
+    Custom encoder for numpy data types.
+    """
+    def default(self, obj):
+        if isinstance(obj, np.integer):
+            return int(obj)
+        elif isinstance(obj, np.floating):
+            return float(obj)
+        elif isinstance(obj, np.ndarray):
+            return obj.tolist()
+        else:
+            return super(NumpyEncoder, self).default(obj)

pyscan/measurement/abstract_experiment.py

@@ -9,6 +9,7 @@
                             recursive_to_dict,
                             is_list_type)
 from pyscan.measurement.scans import PropertyScan, RepeatScan
+from pyscan.general.json_encoder import NumpyEncoder
 
 
 class AbstractExperiment(ItemAttribute):
@@ -229,8 +230,8 @@ def save_metadata(self):
         data = recursive_to_dict(self.__dict__)
 
         with h5py.File(save_name, 'a') as f:
-            f.attrs['runinfo'] = json.dumps(data['runinfo'])
-            f.attrs['devices'] = json.dumps(data['devices'])
+            f.attrs['runinfo'] = json.dumps(data['runinfo'], cls=NumpyEncoder)
+            f.attrs['devices'] = json.dumps(data['devices'], cls=NumpyEncoder)
 
     def start_thread(self):
         '''Starts experiment as a background thread, this works in conjunction with live plot