tensorflow2.0 新特性小练习

基于tf2.0 对Kaggel Google street view characters classify 项目练手，熟悉一下tf2.0的新特性

下载下来kaggle的数据集如下：

所有训练数据在train文件夹中， labels在trainLabels.cvs文件中， label文件格式如下：

分别每个label对应其图片的名称

首先对数据进行预处理总共有61个类别从a-z， A-Z， 0-9等，代码如下：

from __future__ import absolute_import, division, print_function, unicode_literals
import numpy as np
import tensorflow as tf
from tensorflow.python import keras
import csv
import pathlib
keras.backend.clear_session()
csv_filepath = 'E:\\work\\Kaggle\\street-view-getting-started-with-julia\\trainLabels.csv'
data_root_path = 'E:\\work\\Kaggle\\street-view-getting-started-with-julia\\train'
csv_file = csv.reader(open(csv_filepath, 'r'))
label_container = []
labels = []
all_image_labels = []
AUTOTUNE = tf.data.experimental.AUTOTUNE

for cnt in csv_file:
    if cnt[1] not in labels:
        labels.append(cnt[1])
    label_container.append(cnt)

labels = labels[1:]
label_container = label_container[1:]
labels = np.sort(labels)
labels_to_index = dict((name, index) for index,name in enumerate(labels))

data_root = pathlib.Path(data_root_path)
all_image_paths = list(data_root.glob('*'))
all_image_paths = [str(path) for path in all_image_paths]


for item in data_root.iterdir():
    # all_img_path.append(item)
    name = item.name[:-4]
    for match in label_container:
        if name == match[0]:
　　         all_image_labels.append(key if value == match[1] 
                                    for key, value in enumerate(labels_to_index))

生成的all_image_paths 和 all_image_labels分别包含如下:

因为测试集没有label，所以把训练集分三份，并用tf.data.Data去映射数据空间

train_img_path = all_image_paths[:4000]
val_img_path = all_image_paths[4000:5000]
test_img_path = all_image_paths[5000:]

train_img_labels = all_image_labels[:4000]
val_img_labels = all_image_labels[4000:5000]
test_img_labels = all_image_labels[5000:]


raw_train_ds = tf.data.Dataset.from_tensor_slices((train_img_path, train_img_labels))
raw_val_ds = tf.data.Dataset.from_tensor_slices((val_img_path, val_img_labels))
raw_test_ds = tf.data.Dataset.from_tensor_slices((test_img_path, test_img_labels))

Scale 图片，并对其做数据增强，来满足translation invarience

tensorflow2.0 新特性小练习

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