如何展平测试图像数据集并创建一批（展平图像，标签）元组？

Question

我在 Handwritten Math's symbol Classification 工作，使用联合学习。我已经对keras.preprocessing.image.ImageDataGenerator中的图像进行了预处理，并获得了每张图像的标签。

from keras.preprocessing.image import ImageDataGenerator

train_datagen = ImageDataGenerator(
        rescale=1./255,
        shear_range=0.2,
        zoom_range=0.2,
        horizontal_flip=True)
train_dataset = train_datagen.flow_from_directory(
        'train_test_data/train/',
        target_size=(45,45),
        batch_size=32,
        class_mode='categorical')

获取标签：

import os
# make label list '!/exp87530.jpg'
def make_labels(train_dataset):
  labels = train_dataset.filenames
  label = []
  for l in labels:
    l = l.split(os.path.sep)[0]
    label.append(l)
  return label

我如何制作一个需要发送给客户端的扁平图像和标签的元组？从 tensorflow 教程中可以看出 Building Your Own Federated Learning Algorithm

来自教程：

import 
emnist_train, emnist_test = tff.simulation.datasets.emnist.load_data()

NUM_CLIENTS = 10
BATCH_SIZE = 20

def preprocess(dataset):

  def batch_format_fn(element):
    """Flatten a batch of EMNIST data and return a (features, label) tuple."""
    return (tf.reshape(element['pixels'], [-1, 784]), 
            tf.reshape(element['label'], [-1, 1]))

  return dataset.batch(BATCH_SIZE).map(batch_format_fn)

Answer 1

您可以尝试这样的操作：

import tensorflow as tf

flowers = tf.keras.utils.get_file(
    'flower_photos',
    'https://storage.googleapis.com/download.tensorflow.org/example_images/flower_photos.tgz',
    untar=True)

img_gen = tf.keras.preprocessing.image.ImageDataGenerator(rescale=1./255,
        shear_range=0.2,
        zoom_range=0.2,
        horizontal_flip=True)


ds = tf.data.Dataset.from_generator(
    lambda: img_gen.flow_from_directory(flowers, target_size=(45,45), batch_size=10, shuffle=True),
    output_types=(tf.float32, tf.int32))

def preprocess(dataset):

  def batch_format_fn(x, y):
    """Flatten a batch of EMNIST data and return a (features, label) tuple."""
    return (tf.reshape(x, [-1, 45*45*3]), 
            tf.reshape(y, [-1, 5]))

  return dataset.map(batch_format_fn)

ds = preprocess(ds)
for x,y in ds.take(1):
  print(x.shape, y.shape)

扁平化的数据批次，其中 5 是类/不同标签的数量：

(10, 6075) (10, 5)

如何展平测试图像数据集并创建一批（展平图像，标签）元组？

How to flatten test image dataset and create a batch of tuple of (flattened image , labels)?

python

tensorflow

jupyter-notebook

tensorflow-datasets

federated-learning