simplify dygraph data loader code, test=develop (#21722)

python/paddle/fluid/data_feeder.py

@@ -502,51 +502,3 @@ class DataFeeder(object):
                         "not implemented")
 
         return __reader_creator__
-
-
-class NumpyToLoDTensorConverter(object):
-    def __init__(self, place):
-        self.place = place
-        self.data = []
-        self._reset()
-
-    def _reset(self):
-        self.data = []
-
-    def feed(self, data):
-        self.data.append(data)
-
-    def done(self):
-        arr = numpy.array(self.data)
-        t = core.LoDTensor()
-        t.set(arr, self.place)
-        self._reset()
-        return t
-
-
-class DygraphListTensorProvider(object):
-    def __init__(self, generator, place):
-        self.generator = generator
-        self.converters = []
-        if place:
-            if isinstance(place, (core.CUDAPlace, core.CPUPlace)):
-                self.place = place
-            else:
-                raise ValueError("Please specify a valid place values \
-                    such as core.CPUPlace or core.CUDAPlace")
-        else:
-            self.place = _current_expected_place()
-
-    def _read_data(self, iterable, place):
-        for items in iterable:
-            if len(self.converters) < len(items):
-                for _ in items:
-                    self.converters.append(NumpyToLoDTensorConverter(place))
-            for each_converter, each_slot in six.moves.zip(self.converters,
-                                                           items):
-                each_converter.feed(each_slot)
-        yield [c.done() for c in self.converters]
-
-    def __call__(self):
-        for batch in self.generator():
-            yield list(self._read_data(batch, self.place))

python/paddle/fluid/reader.py

@@ -21,7 +21,7 @@ import threading
 import paddle
 from .framework import Program, Variable, program_guard, default_main_program, default_startup_program, in_dygraph_mode, cpu_places
 from .executor import global_scope
-from .data_feeder import DataFeeder, BatchedTensorProvider, DygraphListTensorProvider
+from .data_feeder import DataFeeder, BatchedTensorProvider
 from .layers.io import monkey_patch_reader_methods, _copy_reader_var_, double_buffer
 from .unique_name import UniqueNameGenerator
 import logging
@@ -545,11 +545,17 @@ class GeneratorLoader(DataLoaderBase):
 
     def set_sample_list_generator(self, reader, places=None):
         if in_dygraph_mode():
-            provider = DygraphListTensorProvider(reader, places)
 
             def __tensor_reader_impl__():
-                for slots in provider():
-                    yield slots[0]
+                for batch in reader():
+                    slots = []
+                    for items in batch:
+                        for i, item in enumerate(items):
+                            if len(slots) < len(items):
+                                slots.append([item])
+                            else:
+                                slots[i].append(item)
+                    yield slots
         else:
             with program_guard(Program(), Program()):
                 feeder = DataFeeder(