Raspberry Pi : TensorFlow : tf.data を使って画像をロードする

python 起動，最初の設定

作成: 2021-04-24
更新: 2021-04-28

(venv) $ python >>> print(tf.__version__) 1.14.0

>>> import tensorflow as tf

>>> tf.enable_eager_execution()

註１：

(venv) $ pip install -U tensorflow Looking in indexes: https://pypi.org/simple, https://www.piwheels.org/simple Requirement already satisfied: tensorflow in ./venv/lib/python3.7/site-packages (1.14.0) Requirement already satisfied: astor>=0.6.0 in ./venv/lib/python3.7/site-packages (from tensorflow) (0.8.1) Requirement already satisfied: tensorflow-estimator<1.15.0rc0,>=1.14.0rc0 in ./venv/lib/python3.7/site-packages (from tensorflow) (1.14.0) Requirement already satisfied: grpcio>=1.8.6 in ./venv/lib/python3.7/site-packages (from tensorflow) (1.37.0) Requirement already satisfied: google-pasta>=0.1.6 in ./venv/lib/python3.7/site-packages (from tensorflow) (0.2.0) Requirement already satisfied: keras-preprocessing>=1.0.5 in ./venv/lib/python3.7/site-packages (from tensorflow) (1.1.2) Requirement already satisfied: tensorboard<2.1.0,>=2.0.0 in ./venv/lib/python3.7/site-packages (from tensorflow) (2.0.2) Requirement already satisfied: termcolor>=1.1.0 in ./venv/lib/python3.7/site-packages (from tensorflow) (1.1.0) Requirement already satisfied: opt-einsum>=2.3.2 in ./venv/lib/python3.7/site-packages (from tensorflow) (3.3.0) Requirement already satisfied: six>=1.10.0 in /usr/lib/python3/dist-packages (from tensorflow) (1.12.0) Requirement already satisfied: wrapt>=1.11.1 in ./venv/lib/python3.7/site-packages (from tensorflow) (1.12.1) Requirement already satisfied: protobuf>=3.6.1 in ./venv/lib/python3.7/site-packages (from tensorflow) (3.15.8) Requirement already satisfied: gast==0.2.2 in ./venv/lib/python3.7/site-packages (from tensorflow) (0.2.2) Requirement already satisfied: numpy<2.0,>=1.16.0 in ./venv/lib/python3.7/site-packages (from tensorflow) (1.20.2) Requirement already satisfied: wheel>=0.26 in /usr/lib/python3/dist-packages (from tensorflow) (0.32.3) Requirement already satisfied: keras-applications>=1.0.8 in ./venv/lib/python3.7/site-packages (from tensorflow) (1.0.8) Requirement already satisfied: absl-py>=0.7.0 in ./venv/lib/python3.7/site-packages (from tensorflow) (0.12.0) Requirement already satisfied: h5py in ./venv/lib/python3.7/site-packages (from keras-applications>=1.0.8->tensorflow) (3.2.1) Requirement already satisfied: google-auth<2,>=1.6.3 in ./venv/lib/python3.7/site-packages (from tensorboard<2.1.0,>=2.0.0->tensorflow) (1.29.0) Requirement already satisfied: setuptools>=41.0.0 in ./venv/lib/python3.7/site-packages (from tensorboard<2.1.0,>=2.0.0->tensorflow) (56.0.0) Requirement already satisfied: werkzeug>=0.11.15 in /usr/lib/python3/dist-packages (from tensorboard<2.1.0,>=2.0.0->tensorflow) (0.14.1) Requirement already satisfied: requests<3,>=2.21.0 in /usr/lib/python3/dist-packages (from tensorboard<2.1.0,>=2.0.0->tensorflow) (2.21.0) Requirement already satisfied: markdown>=2.6.8 in ./venv/lib/python3.7/site-packages (from tensorboard<2.1.0,>=2.0.0->tensorflow) (3.3.4) Requirement already satisfied: google-auth-oauthlib<0.5,>=0.4.1 in ./venv/lib/python3.7/site-packages (from tensorboard<2.1.0,>=2.0.0->tensorflow) (0.4.4) Requirement already satisfied: pyasn1-modules>=0.2.1 in ./venv/lib/python3.7/site-packages (from google-auth<2,>=1.6.3->tensorboard<2.1.0,>=2.0.0->tensorflow) (0.2.8) Requirement already satisfied: cachetools<5.0,>=2.0.0 in ./venv/lib/python3.7/site-packages (from google-auth<2,>=1.6.3->tensorboard<2.1.0,>=2.0.0->tensorflow) (4.2.1) Requirement already satisfied: rsa<5,>=3.1.4 in ./venv/lib/python3.7/site-packages (from google-auth<2,>=1.6.3->tensorboard<2.1.0,>=2.0.0->tensorflow) (4.7.2) Requirement already satisfied: requests-oauthlib>=0.7.0 in /usr/lib/python3/dist-packages (from google-auth-oauthlib<0.5,>=0.4.1->tensorboard<2.1.0,>=2.0.0->tensorflow) (1.0.0) Requirement already satisfied: importlib-metadata in ./venv/lib/python3.7/site-packages (from markdown>=2.6.8->tensorboard<2.1.0,>=2.0.0->tensorflow) (3.10.1) Requirement already satisfied: pyasn1<0.5.0,>=0.4.6 in ./venv/lib/python3.7/site-packages (from pyasn1-modules>=0.2.1->google-auth<2,>=1.6.3->tensorboard<2.1.0,>=2.0.0->tensorflow) (0.4.8) Requirement already satisfied: cached-property in ./venv/lib/python3.7/site-packages (from h5py->keras-applications>=1.0.8->tensorflow) (1.5.2) Requirement already satisfied: typing-extensions>=3.6.4 in ./venv/lib/python3.7/site-packages (from importlib-metadata->markdown>=2.6.8->tensorboard<2.1.0,>=2.0.0->tensorflow) (3.7.4.3) Requirement already satisfied: zipp>=0.5 in ./venv/lib/python3.7/site-packages (from importlib-metadata->markdown>=2.6.8->tensorboard<2.1.0,>=2.0.0->tensorflow) (3.4.1) (venv) $

註2：	tf.enable_eager_execution() を実行しておかないと，つぎのように，エラーを生じる場面が出てくる：

「all_images」

>>> img_raw = tf.io.read_file(img_path) >>> img_tensor = tf.image.decode_image(img_raw) >>> print(img_tensor.shape) <unknown>

一般に，tensorflow 1.x では「tf.enable_eager_execution()」の実行が必要になる。
── tensorflow 2.x では，「tf.enable_eager_execution()」がデフォルトになっている。

また，tf.enable_eager_execution() は，プログラムの始めに実行しなければならない。
途中でこれを実行すると，つぎのエラーが返される：

>>>> tf.enable_eager_execution() Traceback (most recent call last): File "<stdin>", line 1, in <module> File "/home/pi/venv/lib/python3.7/site-packages/ tensorflow_core/python/framework/ops.py", line 5584, in enable_eager_execution server_def=None) File "/home/pi/venv/lib/python3.7/site-packages/ tensorflow_core/python/framework/ops.py", line 5643, in enable_eager_execution_internal "tf.enable_eager_execution must be called at program startup.") ValueError: tf.enable_eager_execution must be called at program startup.