텍스트 생성을 위한 Federated Learning

!pip install --quiet --upgrade tensorflow_federated_nightly
!pip install --quiet --upgrade nest_asyncio

import nest_asyncio
nest_asyncio.apply()

import collections
import functools
import os
import time

import numpy as np
import tensorflow as tf
import tensorflow_federated as tff

np.random.seed(0)

# Test the TFF is working:
tff.federated_computation(lambda: 'Hello, World!')()

b'Hello, World!'

# A fixed vocabularly of ASCII chars that occur in the works of Shakespeare and Dickens:
vocab = list('dhlptx@DHLPTX $(,048cgkoswCGKOSW[_#\'/37;?bfjnrvzBFJNRVZ"&*.26:\naeimquyAEIMQUY]!%)-159\r')

# Creating a mapping from unique characters to indices
char2idx = {u:i for i, u in enumerate(vocab)}
idx2char = np.array(vocab)

def load_model(batch_size):
  urls = {
      1: 'https://storage.googleapis.com/tff-models-public/dickens_rnn.batch1.kerasmodel',
      8: 'https://storage.googleapis.com/tff-models-public/dickens_rnn.batch8.kerasmodel'}
  assert batch_size in urls, 'batch_size must be in ' + str(urls.keys())
  url = urls[batch_size]
  local_file = tf.keras.utils.get_file(os.path.basename(url), origin=url)  
  return tf.keras.models.load_model(local_file, compile=False)

def generate_text(model, start_string):
  # From https://www.tensorflow.org/tutorials/sequences/text_generation
  num_generate = 200
  input_eval = [char2idx[s] for s in start_string]
  input_eval = tf.expand_dims(input_eval, 0)
  text_generated = []
  temperature = 1.0

  model.reset_states()
  for i in range(num_generate):
    predictions = model(input_eval)
    predictions = tf.squeeze(predictions, 0)
    predictions = predictions / temperature
    predicted_id = tf.random.categorical(
        predictions, num_samples=1)[-1, 0].numpy()
    input_eval = tf.expand_dims([predicted_id], 0)
    text_generated.append(idx2char[predicted_id])

  return (start_string + ''.join(text_generated))

# Text generation requires a batch_size=1 model.
keras_model_batch1 = load_model(batch_size=1)
print(generate_text(keras_model_batch1, 'What of TensorFlow Federated, you ask? '))

Downloading data from https://storage.googleapis.com/tff-models-public/dickens_rnn.batch1.kerasmodel
16195584/16193984 [==============================] - 0s 0us/step
16203776/16193984 [==============================] - 0s 0us/step
What of TensorFlow Federated, you ask? Sall
yesterday. Received the Bailey."

"Mr. Lorry, grimmering himself, or low varked thends the winter, and the eyes of Monsieur
Defarge. "Let his mind, hon in his
life and message; four declare

train_data, test_data = tff.simulation.datasets.shakespeare.load_data()

# Here the play is "The Tragedy of King Lear" and the character is "King".
raw_example_dataset = train_data.create_tf_dataset_for_client(
    'THE_TRAGEDY_OF_KING_LEAR_KING')
# To allow for future extensions, each entry x
# is an OrderedDict with a single key 'snippets' which contains the text.
for x in raw_example_dataset.take(2):
  print(x['snippets'])

tf.Tensor(b'', shape=(), dtype=string)
tf.Tensor(b'What?', shape=(), dtype=string)

# Input pre-processing parameters
SEQ_LENGTH = 100
BATCH_SIZE = 8
BUFFER_SIZE = 100  # For dataset shuffling

# Construct a lookup table to map string chars to indexes,
# using the vocab loaded above:
table = tf.lookup.StaticHashTable(
    tf.lookup.KeyValueTensorInitializer(
        keys=vocab, values=tf.constant(list(range(len(vocab))),
                                       dtype=tf.int64)),
    default_value=0)


def to_ids(x):
  s = tf.reshape(x['snippets'], shape=[1])
  chars = tf.strings.bytes_split(s).values
  ids = table.lookup(chars)
  return ids


def split_input_target(chunk):
  input_text = tf.map_fn(lambda x: x[:-1], chunk)
  target_text = tf.map_fn(lambda x: x[1:], chunk)
  return (input_text, target_text)


def preprocess(dataset):
  return (
      # Map ASCII chars to int64 indexes using the vocab
      dataset.map(to_ids)
      # Split into individual chars
      .unbatch()
      # Form example sequences of SEQ_LENGTH +1
      .batch(SEQ_LENGTH + 1, drop_remainder=True)
      # Shuffle and form minibatches
      .shuffle(BUFFER_SIZE).batch(BATCH_SIZE, drop_remainder=True)
      # And finally split into (input, target) tuples,
      # each of length SEQ_LENGTH.
      .map(split_input_target))

example_dataset = preprocess(raw_example_dataset)
print(example_dataset.element_spec)

(TensorSpec(shape=(8, 100), dtype=tf.int64, name=None), TensorSpec(shape=(8, 100), dtype=tf.int64, name=None))

class FlattenedCategoricalAccuracy(tf.keras.metrics.SparseCategoricalAccuracy):

  def __init__(self, name='accuracy', dtype=tf.float32):
    super().__init__(name, dtype=dtype)

  def update_state(self, y_true, y_pred, sample_weight=None):
    y_true = tf.reshape(y_true, [-1, 1])
    y_pred = tf.reshape(y_pred, [-1, len(vocab), 1])
    return super().update_state(y_true, y_pred, sample_weight)

BATCH_SIZE = 8  # The training and eval batch size for the rest of this tutorial.
keras_model = load_model(batch_size=BATCH_SIZE)
keras_model.compile(
    loss=tf.keras.losses.SparseCategoricalCrossentropy(from_logits=True),
    metrics=[FlattenedCategoricalAccuracy()])

# Confirm that loss is much lower on Shakespeare than on random data
loss, accuracy = keras_model.evaluate(example_dataset.take(5), verbose=0)
print(
    'Evaluating on an example Shakespeare character: {a:3f}'.format(a=accuracy))

# As a sanity check, we can construct some completely random data, where we expect
# the accuracy to be essentially random:
random_guessed_accuracy = 1.0 / len(vocab)
print('Expected accuracy for random guessing: {a:.3f}'.format(
    a=random_guessed_accuracy))
random_indexes = np.random.randint(
    low=0, high=len(vocab), size=1 * BATCH_SIZE * (SEQ_LENGTH + 1))
data = collections.OrderedDict(
    snippets=tf.constant(
        ''.join(np.array(vocab)[random_indexes]), shape=[1, 1]))
random_dataset = preprocess(tf.data.Dataset.from_tensor_slices(data))
loss, accuracy = keras_model.evaluate(random_dataset, steps=10, verbose=0)
print('Evaluating on completely random data: {a:.3f}'.format(a=accuracy))

Downloading data from https://storage.googleapis.com/tff-models-public/dickens_rnn.batch8.kerasmodel
16195584/16193984 [==============================] - 0s 0us/step
16203776/16193984 [==============================] - 0s 0us/step
Evaluating on an example Shakespeare character: 0.402000
Expected accuracy for random guessing: 0.012
Evaluating on completely random data: 0.011

# Clone the keras_model inside `create_tff_model()`, which TFF will
# call to produce a new copy of the model inside the graph that it will 
# serialize. Note: we want to construct all the necessary objects we'll need 
# _inside_ this method.
def create_tff_model():
  # TFF uses an `input_spec` so it knows the types and shapes
  # that your model expects.
  input_spec = example_dataset.element_spec
  keras_model_clone = tf.keras.models.clone_model(keras_model)
  return tff.learning.from_keras_model(
      keras_model_clone,
      input_spec=input_spec,
      loss=tf.keras.losses.SparseCategoricalCrossentropy(from_logits=True),
      metrics=[FlattenedCategoricalAccuracy()])

# This command builds all the TensorFlow graphs and serializes them: 
fed_avg = tff.learning.build_federated_averaging_process(
    model_fn=create_tff_model,
    client_optimizer_fn=lambda: tf.keras.optimizers.SGD(lr=0.5))

state = fed_avg.initialize()
state, metrics = fed_avg.next(state, [example_dataset.take(5)])
print('loss={l:.3f}, accuracy={a:.3f}'.format(
    l=metrics.train.loss, a=metrics.train.accuracy))

loss=4.403, accuracy=0.132

def data(client, source=train_data):
  return preprocess(source.create_tf_dataset_for_client(client)).take(5)


clients = [
    'ALL_S_WELL_THAT_ENDS_WELL_CELIA', 'MUCH_ADO_ABOUT_NOTHING_OTHELLO',
]

train_datasets = [data(client) for client in clients]

# We concatenate the test datasets for evaluation with Keras by creating a 
# Dataset of Datasets, and then identity flat mapping across all the examples.
test_dataset = tf.data.Dataset.from_tensor_slices(
    [data(client, test_data) for client in clients]).flat_map(lambda x: x)

NUM_ROUNDS = 5

# The state of the FL server, containing the model and optimization state.
state = fed_avg.initialize()

# Load our pre-trained Keras model weights into the global model state.
state = tff.learning.state_with_new_model_weights(
    state,
    trainable_weights=[v.numpy() for v in keras_model.trainable_weights],
    non_trainable_weights=[
        v.numpy() for v in keras_model.non_trainable_weights
    ])


def keras_evaluate(state, round_num):
  # Take our global model weights and push them back into a Keras model to
  # use its standard `.evaluate()` method.
  keras_model = load_model(batch_size=BATCH_SIZE)
  keras_model.compile(
      loss=tf.keras.losses.SparseCategoricalCrossentropy(from_logits=True),
      metrics=[FlattenedCategoricalAccuracy()])
  state.model.assign_weights_to(keras_model)
  loss, accuracy = keras_model.evaluate(example_dataset, steps=2, verbose=0)
  print('\tEval: loss={l:.3f}, accuracy={a:.3f}'.format(l=loss, a=accuracy))


for round_num in range(NUM_ROUNDS):
  print('Round {r}'.format(r=round_num))
  keras_evaluate(state, round_num)
  state, metrics = fed_avg.next(state, train_datasets)
  train_metrics = metrics['train']
  print('\tTrain: loss={l:.3f}, accuracy={a:.3f}'.format(
      l=train_metrics['loss'], a=train_metrics['accuracy']))

print('Final evaluation')
keras_evaluate(state, NUM_ROUNDS + 1)

Round 0
    Eval: loss=3.324, accuracy=0.401
    Train: loss=4.360, accuracy=0.155
Round 1
    Eval: loss=4.361, accuracy=0.049
    Train: loss=4.235, accuracy=0.164
Round 2
    Eval: loss=4.219, accuracy=0.177
    Train: loss=4.081, accuracy=0.221
Round 3
    Eval: loss=4.080, accuracy=0.174
    Train: loss=3.940, accuracy=0.226
Round 4
    Eval: loss=3.991, accuracy=0.176
    Train: loss=3.840, accuracy=0.226
Final evaluation
    Eval: loss=3.909, accuracy=0.171

# Set our newly trained weights back in the originally created model.
keras_model_batch1.set_weights([v.numpy() for v in keras_model.weights])
# Text generation requires batch_size=1
print(generate_text(keras_model_batch1, 'What of TensorFlow Federated, you ask? '))

What of TensorFlow Federated, you ask? Shalways, I will call your
compet with any city brought their faces uncompany," besumed him. "When he
sticked Madame Defarge pushed the lamps.

"Have I often but no unison. She had probably come,