Small refactors on the keras.utils module (keras-team#13388)

* Use .format calls for string interpolation on utils

* Use generators over listcomps whenever possible to save memory

keras/utils/conv_utils.py

@@ -32,19 +32,19 @@ def normalize_tuple(value, n, name):
         try:
             value_tuple = tuple(value)
         except TypeError:
-            raise ValueError('The `' + name + '` argument must be a tuple of ' +
-                             str(n) + ' integers. Received: ' + str(value))
+            raise ValueError('The `{}` argument must be a tuple of {} '
+                             'integers. Received: {}'.format(name, n, value))
         if len(value_tuple) != n:
-            raise ValueError('The `' + name + '` argument must be a tuple of ' +
-                             str(n) + ' integers. Received: ' + str(value))
+            raise ValueError('The `{}` argument must be a tuple of {} '
+                             'integers. Received: {}'.format(name, n, value))
         for single_value in value_tuple:
             try:
                 int(single_value)
             except ValueError:
-                raise ValueError('The `' + name + '` argument must be a tuple of ' +
-                                 str(n) + ' integers. Received: ' + str(value) + ' '
-                                 'including element ' + str(single_value) + ' of '
-                                 'type ' + str(type(single_value)))
+                raise ValueError('The `{}` argument must be a tuple of {} '
+                                 'integers. Received: {} including element {} '
+                                 'of type {}'.format(name, n, value, single_value,
+                                                     type(single_value)))
     return value_tuple
 
 
@@ -55,7 +55,7 @@ def normalize_padding(value):
         allowed.add('full')
     if padding not in allowed:
         raise ValueError('The `padding` argument must be one of "valid", "same" '
-                         '(or "causal" for Conv1D). Received: ' + str(padding))
+                         '(or "causal" for Conv1D). Received: {}'.format(padding))
     return padding
 
 

keras/utils/data_utils.py

@@ -67,8 +67,8 @@ def chunk_read(response, chunk_size=8192, reporthook=None):
                     break
 
         with closing(urlopen(url, data)) as response, open(filename, 'wb') as fd:
-                for chunk in chunk_read(response, reporthook=reporthook):
-                    fd.write(chunk)
+            for chunk in chunk_read(response, reporthook=reporthook):
+                fd.write(chunk)
 else:
     from six.moves.urllib.request import urlretrieve
 
@@ -195,10 +195,10 @@ def get_file(fname,
         # File found; verify integrity if a hash was provided.
         if file_hash is not None:
             if not validate_file(fpath, file_hash, algorithm=hash_algorithm):
-                print('A local file was found, but it seems to be '
-                      'incomplete or outdated because the ' + hash_algorithm +
-                      ' file hash does not match the original value of ' +
-                      file_hash + ' so we will re-download the data.')
+                print('A local file was found, but it seems to be incomplete'
+                      ' or outdated because the {} file hash does not match '
+                      'the original value of {} so we will re-download the '
+                      'data.'.format(hash_algorithm, file_hash))
                 download = True
     else:
         download = True
@@ -725,9 +725,9 @@ def get(self):
             while self.queue.qsize() > 0:
                 last_ones.append(self.queue.get(block=True))
             # Wait for them to complete
-            list(map(lambda f: f.wait(), last_ones))
+            [f.wait() for f in last_ones]
             # Keep the good ones
-            last_ones = [future.get() for future in last_ones if future.successful()]
+            last_ones = (future.get() for future in last_ones if future.successful())
             for inputs in last_ones:
                 if inputs is not None:
                     yield inputs

keras/utils/generic_utils.py

@@ -126,7 +126,7 @@ def deserialize_keras_object(identifier, module_objects=None,
         # In this case we are dealing with a Keras config dictionary.
         config = identifier
         if 'class_name' not in config or 'config' not in config:
-            raise ValueError('Improper config format: ' + str(config))
+            raise ValueError('Improper config format: {}'.format(config))
         class_name = config['class_name']
         if custom_objects and class_name in custom_objects:
             cls = custom_objects[class_name]
@@ -136,8 +136,8 @@ def deserialize_keras_object(identifier, module_objects=None,
             module_objects = module_objects or {}
             cls = module_objects.get(class_name)
             if cls is None:
-                raise ValueError('Unknown ' + printable_module_name +
-                                 ': ' + class_name)
+                raise ValueError('Unknown {}: {}'.format(printable_module_name,
+                                                         class_name))
         if hasattr(cls, 'from_config'):
             custom_objects = custom_objects or {}
             if has_arg(cls.from_config, 'custom_objects'):
@@ -163,12 +163,12 @@ def deserialize_keras_object(identifier, module_objects=None,
         else:
             fn = module_objects.get(function_name)
             if fn is None:
-                raise ValueError('Unknown ' + printable_module_name +
-                                 ':' + function_name)
+                raise ValueError('Unknown {}: {}'.format(printable_module_name,
+                                                         function_name))
         return fn
     else:
-        raise ValueError('Could not interpret serialized ' +
-                         printable_module_name + ': ' + identifier)
+        raise ValueError('Could not interpret serialized '
+                         '{}: {}'.format(printable_module_name, identifier))
 
 
 def func_dump(func):
@@ -514,7 +514,7 @@ def unpack_singleton(x):
 
 def object_list_uid(object_list):
     object_list = to_list(object_list)
-    return ', '.join([str(abs(id(x))) for x in object_list])
+    return ', '.join((str(abs(id(x))) for x in object_list))
 
 
 def is_all_none(iterable_or_element):

keras/utils/multi_gpu_utils.py

@@ -153,7 +153,7 @@ def multi_gpu_model(model, gpus=None, cpu_merge=True, cpu_relocation=False):
     if not gpus:
         # Using all visible GPUs when not specifying `gpus`
         # e.g. CUDA_VISIBLE_DEVICES=0,2 python keras_mgpu.py
-        gpus = len([x for x in available_devices if '/gpu:' in x])
+        gpus = len((x for x in available_devices if '/gpu:' in x))
 
     if isinstance(gpus, (list, tuple)):
         if len(gpus) <= 1:

keras/utils/vis_utils.py

@@ -149,7 +149,7 @@ def model_to_dot(model,
                 inputlabels = str(layer.input_shape)
             elif hasattr(layer, 'input_shapes'):
                 inputlabels = ', '.join(
-                    [str(ishape) for ishape in layer.input_shapes])
+                    (str(ishape) for ishape in layer.input_shapes))
             else:
                 inputlabels = 'multiple'
             label = '%s\n|{input:|output:}|{{%s}|{%s}}' % (label,