Add inference example and unit-test for fit-a-line book chapter (#8208)

* initial commit

* minor fix

* remove redundency

* address comments

paddle/inference/tests/book/CMakeLists.txt

@@ -24,6 +24,7 @@ function(inference_test TARGET_NAME)
   endforeach()
 endfunction(inference_test)
 
+inference_test(fit_a_line)
 inference_test(recognize_digits ARGS mlp)
 inference_test(image_classification ARGS vgg resnet)
 inference_test(label_semantic_roles)

paddle/inference/tests/book/test_inference_fit_a_line.cc

+/* Copyright (c) 2018 PaddlePaddle Authors. All Rights Reserve.
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+    http://www.apache.org/licenses/LICENSE-2.0
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License. */
+
+#include <gtest/gtest.h>
+#include "gflags/gflags.h"
+#include "test_helper.h"
+
+DEFINE_string(dirname, "", "Directory of the inference model.");
+
+TEST(inference, fit_a_line) {
+  if (FLAGS_dirname.empty()) {
+    LOG(FATAL) << "Usage: ./example --dirname=path/to/your/model";
+  }
+
+  LOG(INFO) << "FLAGS_dirname: " << FLAGS_dirname << std::endl;
+  std::string dirname = FLAGS_dirname;
+
+  // 0. Call `paddle::framework::InitDevices()` initialize all the devices
+  // In unittests, this is done in paddle/testing/paddle_gtest_main.cc
+
+  paddle::framework::LoDTensor input;
+  // The second dim of the input tensor should be 13
+  // The input data should be >= 0
+  int64_t batch_size = 10;
+  SetupTensor<float>(
+      input, {batch_size, 13}, static_cast<float>(0), static_cast<float>(10));
+  std::vector<paddle::framework::LoDTensor*> cpu_feeds;
+  cpu_feeds.push_back(&input);
+
+  paddle::framework::LoDTensor output1;
+  std::vector<paddle::framework::LoDTensor*> cpu_fetchs1;
+  cpu_fetchs1.push_back(&output1);
+
+  // Run inference on CPU
+  TestInference<paddle::platform::CPUPlace>(dirname, cpu_feeds, cpu_fetchs1);
+  LOG(INFO) << output1.dims();
+
+#ifdef PADDLE_WITH_CUDA
+  paddle::framework::LoDTensor output2;
+  std::vector<paddle::framework::LoDTensor*> cpu_fetchs2;
+  cpu_fetchs2.push_back(&output2);
+
+  // Run inference on CUDA GPU
+  TestInference<paddle::platform::CUDAPlace>(dirname, cpu_feeds, cpu_fetchs2);
+  LOG(INFO) << output2.dims();
+
+  CheckError<float>(output1, output2);
+#endif
+}

python/paddle/v2/fluid/tests/book/test_fit_a_line.py

@@ -15,15 +15,13 @@
 import paddle.v2 as paddle
 import paddle.v2.fluid as fluid
 import contextlib
+import numpy
 import unittest
 import math
 import sys
 
 
-def main(use_cuda):
-    if use_cuda and not fluid.core.is_compiled_with_cuda():
-        return
-
+def train(use_cuda, save_dirname):
     x = fluid.layers.data(name='x', shape=[13], dtype='float32')
 
     y_predict = fluid.layers.fc(input=x, size=1, act=None)
@@ -51,14 +49,15 @@ def main(use_cuda):
 
     PASS_NUM = 100
     for pass_id in range(PASS_NUM):
-        fluid.io.save_persistables(exe, "./fit_a_line.model/")
-        fluid.io.load_persistables(exe, "./fit_a_line.model/")
         for data in train_reader():
             avg_loss_value, = exe.run(fluid.default_main_program(),
                                       feed=feeder.feed(data),
                                       fetch_list=[avg_cost])
             print(avg_loss_value)
             if avg_loss_value[0] < 10.0:
+                if save_dirname is not None:
+                    fluid.io.save_inference_model(save_dirname, ['x'],
+                                                  [y_predict], exe)
                 return
             if math.isnan(float(avg_loss_value)):
                 sys.exit("got NaN loss, training failed.")
@@ -66,6 +65,43 @@ def main(use_cuda):
         avg_loss_value[0]))
 
 
+def infer(use_cuda, save_dirname=None):
+    if save_dirname is None:
+        return
+
+    place = fluid.CUDAPlace(0) if use_cuda else fluid.CPUPlace()
+    exe = fluid.Executor(place)
+
+    # Use fluid.io.load_inference_model to obtain the inference program desc,
+    # the feed_target_names (the names of variables that will be feeded 
+    # data using feed operators), and the fetch_targets (variables that 
+    # we want to obtain data from using fetch operators).
+    [inference_program, feed_target_names,
+     fetch_targets] = fluid.io.load_inference_model(save_dirname, exe)
+
+    # The input's dimension should be 2-D and the second dim is 13
+    # The input data should be >= 0
+    batch_size = 10
+    tensor_x = numpy.random.uniform(0, 10, [batch_size, 13]).astype("float32")
+    assert feed_target_names[0] == 'x'
+    results = exe.run(inference_program,
+                      feed={feed_target_names[0]: tensor_x},
+                      fetch_list=fetch_targets)
+    print("infer shape: ", results[0].shape)
+    print("infer results: ", results[0])
+
+
+def main(use_cuda):
+    if use_cuda and not fluid.core.is_compiled_with_cuda():
+        return
+
+    # Directory for saving the trained model
+    save_dirname = "fit_a_line.inference.model"
+
+    train(use_cuda, save_dirname)
+    infer(use_cuda, save_dirname)
+
+
 class TestFitALine(unittest.TestCase):
     def test_cpu(self):
         with self.program_scope_guard():