Remove legacy unicode() support in Keras.

PiperOrigin-RevId: 333447364
Change-Id: I33c1298f5dd7dcdd2cb6468d92162c7bb2cb1cf7

tensorflow/python/keras/callbacks.py

@@ -2566,6 +2566,8 @@ class CSVLogger(Callback):
         delimiter = self.sep
 
       fieldnames = ['epoch'] + self.keys
+      if six.PY2:
+        fieldnames = [unicode(x) for x in fieldnames]
 
       self.writer = csv.DictWriter(
           self.csv_file,

tensorflow/python/keras/engine/data_adapter.py

@@ -61,6 +61,13 @@ try:
 except ImportError:
   pd = None
 
+try:
+  # In Python2 unicode is a scalar type
+  scalar_types = (float, int, str, unicode)
+except NameError:
+  # In Python3 unicode is not present, it always uses string
+  scalar_types = (float, int, str)
+
 
 @six.add_metaclass(abc.ABCMeta)
 class DataAdapter(object):
@@ -610,7 +617,7 @@ class ListsOfScalarsDataAdapter(DataAdapter):
 
   @staticmethod
   def _is_list_of_scalars(inp):
-    if isinstance(inp, (float, int, str)):
+    if isinstance(inp, scalar_types):
       return True
     if isinstance(inp, (list, tuple)):
       return ListsOfScalarsDataAdapter._is_list_of_scalars(inp[0])