[core][dataset][data] Improve code

darfix/core/dataset.py

@@ -1359,18 +1359,16 @@ class Data(numpy.ndarray):
     def __new__(cls, urls, metadata, in_memory=True, data=None):
         urls = numpy.asarray(urls)
         if in_memory:
-            if data is not None and urls.shape == data.shape[:-2]:
-                input_data = data
-            else:
+            if data is None or urls.shape != data.shape[:-2]:
                 # Create array as stack of images
                 input_data = []
                 for url in urls.flatten():
-                    input_data += [utils.get_data(url)]
-                input_data = numpy.asarray(input_data)
+                    input_data.append(utils.get_data(url))
+                data = numpy.asarray(input_data)
             shape = list(urls.shape)
-            shape.append(input_data.shape[-2])
-            shape.append(input_data.shape[-1])
-            obj = input_data.reshape(shape).view(cls)
+            shape.append(data.shape[-2])
+            shape.append(data.shape[-1])
+            obj = data.reshape(shape).view(cls)
         else:
             # Access image one at a time using url
             obj = super(Data, cls).__new__(cls, urls.shape)