Gluon end to end tutorial (apache#13411)

* initial draft gluon tutorial

* add reference

* add cpp inference

* improve wording

* address pr comments

* add util functions on dataset

* move util file

* update link

* fix typo, add test

* allow download

* update wording

* update links

* address comments

* use lr scheduler with optimizer

* separate into 2 tutorials

* add c++ tutorial to test whitelist

docs/tutorial_utils/data/oxford_102_flower_dataset.py

@@ -0,0 +1,219 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you 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.
+
+
+"""
+This scripts downloads and prepares the Oxford 102 Category Flower Dataset for training
+Dataset is from: http://www.robots.ox.ac.uk/~vgg/data/flowers/102/index.html
+Script is modified from: https://github.com/Arsey/keras-transfer-learning-for-oxford102
+"""
+
+import glob
+import os
+import tarfile
+from shutil import copyfile
+
+import numpy as np
+from mxnet import gluon
+from scipy.io import loadmat
+
+label_names = [
+    'pink primrose',
+    'hard-leaved pocket orchid',
+    'canterbury bells',
+    'sweet pea',
+    'english marigold',
+    'tiger lily',
+    'moon orchid',
+    'bird of paradise',
+    'monkshood',
+    'globe thistle',
+    'snapdragon',
+    "colt's foot",
+    'king protea',
+    'spear thistle',
+    'yellow iris',
+    'globe-flower',
+    'purple coneflower',
+    'peruvian lily',
+    'balloon flower',
+    'giant white arum lily',
+    'fire lily',
+    'pincushion flower',
+    'fritillary',
+    'red ginger',
+    'grape hyacinth',
+    'corn poppy',
+    'prince of wales feathers',
+    'stemless gentian',
+    'artichoke',
+    'sweet william',
+    'carnation',
+    'garden phlox',
+    'love in the mist',
+    'mexican aster',
+    'alpine sea holly',
+    'ruby-lipped cattleya',
+    'cape flower',
+    'great masterwort',
+    'siam tulip',
+    'lenten rose',
+    'barbeton daisy',
+    'daffodil',
+    'sword lily',
+    'poinsettia',
+    'bolero deep blue',
+    'wallflower',
+    'marigold',
+    'buttercup',
+    'oxeye daisy',
+    'common dandelion',
+    'petunia',
+    'wild pansy',
+    'primula',
+    'sunflower',
+    'pelargonium',
+    'bishop of llandaff',
+    'gaura',
+    'geranium',
+    'orange dahlia',
+    'pink-yellow dahlia?',
+    'cautleya spicata',
+    'japanese anemone',
+    'black-eyed susan',
+    'silverbush',
+    'californian poppy',
+    'osteospermum',
+    'spring crocus',
+    'bearded iris',
+    'windflower',
+    'tree poppy',
+    'gazania',
+    'azalea',
+    'water lily',
+    'rose',
+    'thorn apple',
+    'morning glory',
+    'passion flower',
+    'lotus',
+    'toad lily',
+    'anthurium',
+    'frangipani',
+    'clematis',
+    'hibiscus',
+    'columbine',
+    'desert-rose',
+    'tree mallow',
+    'magnolia',
+    'cyclamen',
+    'watercress',
+    'canna lily',
+    'hippeastrum ',
+    'bee balm',
+    'ball moss',
+    'foxglove',
+    'bougainvillea',
+    'camellia',
+    'mallow',
+    'mexican petunia',
+    'bromelia',
+    'blanket flower',
+    'trumpet creeper',
+    'blackberry lily'
+]
+
+def download_data():
+    data_url = 'http://www.robots.ox.ac.uk/~vgg/data/flowers/102/'
+    image_file_name = '102flowers.tgz'
+    label_file_name = 'imagelabels.mat'
+    setid_file_name = 'setid.mat'
+
+    global data_path, image_path, label_path, setid_path
+    image_path = os.path.join(data_path, image_file_name)
+    label_path = os.path.join(data_path, label_file_name)
+    setid_path = os.path.join(data_path, setid_file_name)
+    # download the dataset into current directory
+    if not os.path.exists(data_path):
+        os.mkdir(data_path)
+    if not os.path.isfile(image_path):
+        gluon.utils.download(url=data_url + image_file_name, path=data_path)
+    if not os.path.exists(os.path.join(data_path, 'jpg')):
+        print("Extracting downloaded dataset...")
+        tarfile.open(image_path).extractall(path=data_path)
+    if not os.path.isfile(label_path):
+        gluon.utils.download(url=data_url + label_file_name, path=data_path)
+    if not os.path.isfile(setid_path):
+        gluon.utils.download(url=data_url + setid_file_name, path=data_path)
+
+
+def prepare_data():
+    # Read .mat file containing training, testing, and validation sets.
+    global data_path, image_path, label_path, setid_path, label_names
+    setid = loadmat(setid_path)
+
+    idx_train = setid['trnid'][0] - 1
+    idx_test = setid['tstid'][0] - 1
+    idx_valid = setid['valid'][0] - 1
+
+    # Read .mat file containing image labels.
+    image_labels = loadmat(label_path)['labels'][0]
+
+    # Subtract one to get 0-based labels
+    image_labels -= 1
+
+    # convert label from number to flower names
+    image_labels = [label_names[i] for i in image_labels]
+    # extracted images are stored in folder 'jpg'
+    files = sorted(glob.glob(os.path.join(data_path, 'jpg', '*.jpg')))
+    file_label_pairs = np.array([i for i in zip(files, image_labels)])
+
+    # move files from extracted folder to train, test, valid
+    move_files('train', file_label_pairs[idx_test, :])
+    move_files('test', file_label_pairs[idx_train, :])
+    move_files('valid', file_label_pairs[idx_valid, :])
+
+
+def move_files(dir_name, file_label_pairs):
+    data_segment_dir = os.path.join(data_path, dir_name)
+    if not os.path.exists(data_segment_dir):
+        os.mkdir(data_segment_dir)
+
+    for label in label_names:
+        class_dir = os.path.join(data_segment_dir, label)
+        if not os.path.exists(class_dir):
+            os.mkdir(class_dir)
+
+    for file, label in file_label_pairs:
+        src = str(file)
+        dst = os.path.join(data_path, dir_name, label, src.split(os.sep)[-1])
+        copyfile(src, dst)
+
+
+def generate_synset():
+    with open('synset.txt', 'w') as f:
+        # Gluon Dataset API will load synset in sorted order
+        for label in sorted(label_names):
+            f.write(label.strip() + '\n')
+        f.close()
+
+
+def get_data(dir_name):
+    global data_path
+    data_path = dir_name
+    download_data()
+    prepare_data()
+    generate_synset()