ヘルプKaggleにTensorFlowグレートバリアリーフを保護チャレンジに参加

量子化対応トレーニング総合ガイド

TensorFlow.orgで表示 GoogleColabで実行 GitHubでソースを表示 ノートブックをダウンロード

Keras量子化対応トレーニングの包括的なガイドへようこそ。

このページでは、さまざまなユースケースについて説明し、それぞれのAPIの使用方法を示します。あなたが必要とどのAPIを知ったら、中のパラメータと低レベルの詳細を見つけるAPIのドキュメントを

次のユースケースについて説明します。

  • これらの手順で、8ビット量子化を使用してモデルをデプロイします。
    • 量子化対応モデルを定義します。
    • Keras HDF5モデルの場合のみ、特別なチェックポイントと逆シリアル化ロジックを使用してください。それ以外の場合、トレーニングは標準です。
    • 量子化対応モデルから量子化モデルを作成します。
  • 量子化を試してください。
    • 実験用のものには、展開へのサポートされたパスがありません。
    • カスタムKerasレイヤーは実験に含まれます。

設定

必要なAPIを見つけて目的を理解するために、実行することはできますが、このセクションを読むことはスキップしてください。

! pip uninstall -y tensorflow
! pip install -q tf-nightly
! pip install -q tensorflow-model-optimization

import tensorflow as tf
import numpy as np
import tensorflow_model_optimization as tfmot

import tempfile

input_shape = [20]
x_train = np.random.randn(1, 20).astype(np.float32)
y_train = tf.keras.utils.to_categorical(np.random.randn(1), num_classes=20)

def setup_model():
  model = tf.keras.Sequential([
      tf.keras.layers.Dense(20, input_shape=input_shape),
      tf.keras.layers.Flatten()
  ])
  return model

def setup_pretrained_weights():
  model= setup_model()

  model.compile(
      loss=tf.keras.losses.categorical_crossentropy,
      optimizer='adam',
      metrics=['accuracy']
  )

  model.fit(x_train, y_train)

  _, pretrained_weights = tempfile.mkstemp('.tf')

  model.save_weights(pretrained_weights)

  return pretrained_weights

def setup_pretrained_model():
  model = setup_model()
  pretrained_weights = setup_pretrained_weights()
  model.load_weights(pretrained_weights)
  return model

setup_model()
pretrained_weights = setup_pretrained_weights()
2021-10-01 11:29:25.336019: E tensorflow/stream_executor/cuda/cuda_driver.cc:271] failed call to cuInit: CUDA_ERROR_NO_DEVICE: no CUDA-capable device is detected

量子化対応モデルを定義する

次の方法でモデルを定義することにより、に記載されているバックエンドへの展開に利用できるパスがある概要ページが。デフォルトでは、8ビットの量子化が使用されます。

モデル全体を定量化する

あなたのユースケース:

  • サブクラス化されたモデルはサポートされていません。

モデルの精度を高めるためのヒント:

  • 「いくつかのレイヤーを量子化する」を試して、精度を最も低下させるレイヤーの量子化をスキップしてください。
  • 一般に、最初からトレーニングするのではなく、量子化を意識したトレーニングで微調整することをお勧めします。

量子化のモデル全体に認識させるために、適用tfmot.quantization.keras.quantize_modelモデルに。

base_model = setup_model()
base_model.load_weights(pretrained_weights) # optional but recommended for model accuracy

quant_aware_model = tfmot.quantization.keras.quantize_model(base_model)
quant_aware_model.summary()
Model: "sequential_2"
_________________________________________________________________
 Layer (type)                Output Shape              Param #   
=================================================================
 quantize_layer (QuantizeLay  (None, 20)               3         
 er)                                                             
                                                                 
 quant_dense_2 (QuantizeWrap  (None, 20)               425       
 perV2)                                                          
                                                                 
 quant_flatten_2 (QuantizeWr  (None, 20)               1         
 apperV2)                                                        
                                                                 
=================================================================
Total params: 429
Trainable params: 420
Non-trainable params: 9
_________________________________________________________________

いくつかのレイヤーを定量化する

モデルの量子化は、精度に悪影響を与える可能性があります。モデルのレイヤーを選択的に量子化して、精度、速度、モデルサイズの間のトレードオフを調べることができます。

あなたのユースケース:

  • 完全に量子化されたモデル(EdgeTPU v1、ほとんどのDSPなど)でのみ適切に機能するバックエンドにデプロイするには、「モデル全体の量子化」を試してください。

モデルの精度を高めるためのヒント:

  • 一般に、最初からトレーニングするのではなく、量子化を意識したトレーニングで微調整することをお勧めします。
  • 最初のレイヤーではなく、後のレイヤーを量子化してみてください。
  • 重要なレイヤー(注意メカニズムなど)の量子化は避けてください。

以下の例では、唯一の量子化Dense層を。

# Create a base model
base_model = setup_model()
base_model.load_weights(pretrained_weights) # optional but recommended for model accuracy

# Helper function uses `quantize_annotate_layer` to annotate that only the 
# Dense layers should be quantized.
def apply_quantization_to_dense(layer):
  if isinstance(layer, tf.keras.layers.Dense):
    return tfmot.quantization.keras.quantize_annotate_layer(layer)
  return layer

# Use `tf.keras.models.clone_model` to apply `apply_quantization_to_dense` 
# to the layers of the model.
annotated_model = tf.keras.models.clone_model(
    base_model,
    clone_function=apply_quantization_to_dense,
)

# Now that the Dense layers are annotated,
# `quantize_apply` actually makes the model quantization aware.
quant_aware_model = tfmot.quantization.keras.quantize_apply(annotated_model)
quant_aware_model.summary()
WARNING:tensorflow:Unresolved object in checkpoint: (root).optimizer
WARNING:tensorflow:Unresolved object in checkpoint: (root).optimizer.iter
WARNING:tensorflow:Unresolved object in checkpoint: (root).optimizer.beta_1
WARNING:tensorflow:Unresolved object in checkpoint: (root).optimizer.beta_2
WARNING:tensorflow:Unresolved object in checkpoint: (root).optimizer.decay
WARNING:tensorflow:Unresolved object in checkpoint: (root).optimizer.learning_rate
WARNING:tensorflow:Unresolved object in checkpoint: (root).optimizer's state 'm' for (root).layer_with_weights-0.kernel
WARNING:tensorflow:Unresolved object in checkpoint: (root).optimizer's state 'm' for (root).layer_with_weights-0.bias
WARNING:tensorflow:Unresolved object in checkpoint: (root).optimizer's state 'v' for (root).layer_with_weights-0.kernel
WARNING:tensorflow:Unresolved object in checkpoint: (root).optimizer's state 'v' for (root).layer_with_weights-0.bias
WARNING:tensorflow:A checkpoint was restored (e.g. tf.train.Checkpoint.restore or tf.keras.Model.load_weights) but not all checkpointed values were used. See above for specific issues. Use expect_partial() on the load status object, e.g. tf.train.Checkpoint.restore(...).expect_partial(), to silence these warnings, or use assert_consumed() to make the check explicit. See https://www.tensorflow.org/guide/checkpoint#loading_mechanics for details.
Model: "sequential_3"
_________________________________________________________________
 Layer (type)                Output Shape              Param #   
=================================================================
 quantize_layer_1 (QuantizeL  (None, 20)               3         
 ayer)                                                           
                                                                 
 quant_dense_3 (QuantizeWrap  (None, 20)               425       
 perV2)                                                          
                                                                 
 flatten_3 (Flatten)         (None, 20)                0         
                                                                 
=================================================================
Total params: 428
Trainable params: 420
Non-trainable params: 8
_________________________________________________________________

この例では、量子化するかを決定する層の種類を使用しますが、最も簡単な方法は、特定の層は、その設定することで量子化するためにnameプロパティを、とでその名前を探しclone_function

print(base_model.layers[0].name)
dense_3

読みやすくなりますが、モデルの精度が低下する可能性があります

これは、量子化対応トレーニングによる微調整と互換性がないため、上記の例よりも精度が低くなる可能性があります。

機能例

# Use `quantize_annotate_layer` to annotate that the `Dense` layer
# should be quantized.
i = tf.keras.Input(shape=(20,))
x = tfmot.quantization.keras.quantize_annotate_layer(tf.keras.layers.Dense(10))(i)
o = tf.keras.layers.Flatten()(x)
annotated_model = tf.keras.Model(inputs=i, outputs=o)

# Use `quantize_apply` to actually make the model quantization aware.
quant_aware_model = tfmot.quantization.keras.quantize_apply(annotated_model)

# For deployment purposes, the tool adds `QuantizeLayer` after `InputLayer` so that the
# quantized model can take in float inputs instead of only uint8.
quant_aware_model.summary()
Model: "model"
_________________________________________________________________
 Layer (type)                Output Shape              Param #   
=================================================================
 input_1 (InputLayer)        [(None, 20)]              0         
                                                                 
 quantize_layer_2 (QuantizeL  (None, 20)               3         
 ayer)                                                           
                                                                 
 quant_dense_4 (QuantizeWrap  (None, 10)               215       
 perV2)                                                          
                                                                 
 flatten_4 (Flatten)         (None, 10)                0         
                                                                 
=================================================================
Total params: 218
Trainable params: 210
Non-trainable params: 8
_________________________________________________________________

順次例

# Use `quantize_annotate_layer` to annotate that the `Dense` layer
# should be quantized.
annotated_model = tf.keras.Sequential([
  tfmot.quantization.keras.quantize_annotate_layer(tf.keras.layers.Dense(20, input_shape=input_shape)),
  tf.keras.layers.Flatten()
])

# Use `quantize_apply` to actually make the model quantization aware.
quant_aware_model = tfmot.quantization.keras.quantize_apply(annotated_model)

quant_aware_model.summary()
Model: "sequential_4"
_________________________________________________________________
 Layer (type)                Output Shape              Param #   
=================================================================
 quantize_layer_3 (QuantizeL  (None, 20)               3         
 ayer)                                                           
                                                                 
 quant_dense_5 (QuantizeWrap  (None, 20)               425       
 perV2)                                                          
                                                                 
 flatten_5 (Flatten)         (None, 20)                0         
                                                                 
=================================================================
Total params: 428
Trainable params: 420
Non-trainable params: 8
_________________________________________________________________

チェックポイントと逆シリアル化

ご利用の場合:このコードは、唯一のHDF5モデル形式(ないHDF5重みや他のフォーマット)のために必要とされます。

# Define the model.
base_model = setup_model()
base_model.load_weights(pretrained_weights) # optional but recommended for model accuracy
quant_aware_model = tfmot.quantization.keras.quantize_model(base_model)

# Save or checkpoint the model.
_, keras_model_file = tempfile.mkstemp('.h5')
quant_aware_model.save(keras_model_file)

# `quantize_scope` is needed for deserializing HDF5 models.
with tfmot.quantization.keras.quantize_scope():
  loaded_model = tf.keras.models.load_model(keras_model_file)

loaded_model.summary()
WARNING:tensorflow:Unresolved object in checkpoint: (root).optimizer
WARNING:tensorflow:Unresolved object in checkpoint: (root).optimizer.iter
WARNING:tensorflow:Unresolved object in checkpoint: (root).optimizer.beta_1
WARNING:tensorflow:Unresolved object in checkpoint: (root).optimizer.beta_2
WARNING:tensorflow:Unresolved object in checkpoint: (root).optimizer.decay
WARNING:tensorflow:Unresolved object in checkpoint: (root).optimizer.learning_rate
WARNING:tensorflow:Unresolved object in checkpoint: (root).optimizer's state 'm' for (root).layer_with_weights-0.kernel
WARNING:tensorflow:Unresolved object in checkpoint: (root).optimizer's state 'm' for (root).layer_with_weights-0.bias
WARNING:tensorflow:Unresolved object in checkpoint: (root).optimizer's state 'v' for (root).layer_with_weights-0.kernel
WARNING:tensorflow:Unresolved object in checkpoint: (root).optimizer's state 'v' for (root).layer_with_weights-0.bias
WARNING:tensorflow:A checkpoint was restored (e.g. tf.train.Checkpoint.restore or tf.keras.Model.load_weights) but not all checkpointed values were used. See above for specific issues. Use expect_partial() on the load status object, e.g. tf.train.Checkpoint.restore(...).expect_partial(), to silence these warnings, or use assert_consumed() to make the check explicit. See https://www.tensorflow.org/guide/checkpoint#loading_mechanics for details.
WARNING:tensorflow:Compiled the loaded model, but the compiled metrics have yet to be built. `model.compile_metrics` will be empty until you train or evaluate the model.
WARNING:tensorflow:No training configuration found in the save file, so the model was *not* compiled. Compile it manually.
Model: "sequential_5"
_________________________________________________________________
 Layer (type)                Output Shape              Param #   
=================================================================
 quantize_layer_4 (QuantizeL  (None, 20)               3         
 ayer)                                                           
                                                                 
 quant_dense_6 (QuantizeWrap  (None, 20)               425       
 perV2)                                                          
                                                                 
 quant_flatten_6 (QuantizeWr  (None, 20)               1         
 apperV2)                                                        
                                                                 
=================================================================
Total params: 429
Trainable params: 420
Non-trainable params: 9
_________________________________________________________________

量子化モデルを作成して展開する

一般に、使用するデプロイメントバックエンドのドキュメントを参照してください。

これはTFLiteバックエンドの例です。

base_model = setup_pretrained_model()
quant_aware_model = tfmot.quantization.keras.quantize_model(base_model)

# Typically you train the model here.

converter = tf.lite.TFLiteConverter.from_keras_model(quant_aware_model)
converter.optimizations = [tf.lite.Optimize.DEFAULT]

quantized_tflite_model = converter.convert()
1/1 [==============================] - 0s 269ms/step - loss: 16.1181 - accuracy: 0.0000e+00
WARNING:tensorflow:Unresolved object in checkpoint: (root).optimizer
WARNING:tensorflow:Unresolved object in checkpoint: (root).optimizer.iter
WARNING:tensorflow:Unresolved object in checkpoint: (root).optimizer.beta_1
WARNING:tensorflow:Unresolved object in checkpoint: (root).optimizer.beta_2
WARNING:tensorflow:Unresolved object in checkpoint: (root).optimizer.decay
WARNING:tensorflow:Unresolved object in checkpoint: (root).optimizer.learning_rate
WARNING:tensorflow:Unresolved object in checkpoint: (root).optimizer's state 'm' for (root).layer_with_weights-0.kernel
WARNING:tensorflow:Unresolved object in checkpoint: (root).optimizer's state 'm' for (root).layer_with_weights-0.bias
WARNING:tensorflow:Unresolved object in checkpoint: (root).optimizer's state 'v' for (root).layer_with_weights-0.kernel
WARNING:tensorflow:Unresolved object in checkpoint: (root).optimizer's state 'v' for (root).layer_with_weights-0.bias
WARNING:tensorflow:A checkpoint was restored (e.g. tf.train.Checkpoint.restore or tf.keras.Model.load_weights) but not all checkpointed values were used. See above for specific issues. Use expect_partial() on the load status object, e.g. tf.train.Checkpoint.restore(...).expect_partial(), to silence these warnings, or use assert_consumed() to make the check explicit. See https://www.tensorflow.org/guide/checkpoint#loading_mechanics for details.
2021-10-01 11:29:28.281011: W tensorflow/python/util/util.cc:368] Sets are not currently considered sequences, but this may change in the future, so consider avoiding using them.
WARNING:absl:Found untraced functions such as dense_7_layer_call_fn, dense_7_layer_call_and_return_conditional_losses, flatten_7_layer_call_fn, flatten_7_layer_call_and_return_conditional_losses, dense_7_layer_call_fn while saving (showing 5 of 10). These functions will not be directly callable after loading.
INFO:tensorflow:Assets written to: /tmp/tmps5i7uwfh/assets
INFO:tensorflow:Assets written to: /tmp/tmps5i7uwfh/assets
2021-10-01 11:29:29.254470: W tensorflow/compiler/mlir/lite/python/tf_tfl_flatbuffer_helpers.cc:363] Ignored output_format.
2021-10-01 11:29:29.254516: W tensorflow/compiler/mlir/lite/python/tf_tfl_flatbuffer_helpers.cc:366] Ignored drop_control_dependency.
WARNING:absl:Buffer deduplication procedure will be skipped when flatbuffer library is not properly loaded
2021-10-01 11:29:29.360670: W tensorflow/compiler/mlir/lite/flatbuffer_export.cc:704] Cannot get mac count for %2 = "tfl.fully_connected"(%0, %1, %cst_0) {fused_activation_function = "NONE", keep_num_dims = false, weights_format = "DEFAULT"} : (tensor<?x20x!quant.uniform<i8:f32, 3.9215686274509805E-9:-1>>, tensor<*x!quant.uniform<i8<-127:127>:f32, 0.047244094488188976>>, none) -> tensor<?x20x!quant.uniform<i8:f32, 0.047058823529411764>>

量子化を試す

ご利用の場合:なし展開へのパスがサポートされている次のAPIの手段を用いて。たとえば、TFLite変換とカーネルの実装は、8ビットの量子化のみをサポートします。これらの機能も実験的なものであり、下位互換性の影響を受けません。

セットアップ:DefaultDenseQuantizeConfig

実験は使用する必要がtfmot.quantization.keras.QuantizeConfig層の重み、アクティベーション、および出力を量子化する方法について説明し、。

以下同じ定義する例であるQuantizeConfigために使用されるDense APIデフォルトで層。

この例では、順方向伝搬中、 LastValueQuantizerで返さget_weights_and_quantizersと呼ばれるlayer.kernel出力を生成する、入力として。出力置き換えはlayer.kernelの元の順方向伝搬にDenseで定義されたロジックを介して、層set_quantize_weights 。同じ考え方がアクティベーションと出力にも当てはまります。

LastValueQuantizer = tfmot.quantization.keras.quantizers.LastValueQuantizer
MovingAverageQuantizer = tfmot.quantization.keras.quantizers.MovingAverageQuantizer

class DefaultDenseQuantizeConfig(tfmot.quantization.keras.QuantizeConfig):
    # Configure how to quantize weights.
    def get_weights_and_quantizers(self, layer):
      return [(layer.kernel, LastValueQuantizer(num_bits=8, symmetric=True, narrow_range=False, per_axis=False))]

    # Configure how to quantize activations.
    def get_activations_and_quantizers(self, layer):
      return [(layer.activation, MovingAverageQuantizer(num_bits=8, symmetric=False, narrow_range=False, per_axis=False))]

    def set_quantize_weights(self, layer, quantize_weights):
      # Add this line for each item returned in `get_weights_and_quantizers`
      # , in the same order
      layer.kernel = quantize_weights[0]

    def set_quantize_activations(self, layer, quantize_activations):
      # Add this line for each item returned in `get_activations_and_quantizers`
      # , in the same order.
      layer.activation = quantize_activations[0]

    # Configure how to quantize outputs (may be equivalent to activations).
    def get_output_quantizers(self, layer):
      return []

    def get_config(self):
      return {}

カスタムKerasレイヤーを定量化する

この例では使用していますDefaultDenseQuantizeConfig量子化するためにCustomLayer

構成の適用は、「量子化を使用した実験」のユースケース全体で同じです。

quantize_annotate_layer = tfmot.quantization.keras.quantize_annotate_layer
quantize_annotate_model = tfmot.quantization.keras.quantize_annotate_model
quantize_scope = tfmot.quantization.keras.quantize_scope

class CustomLayer(tf.keras.layers.Dense):
  pass

model = quantize_annotate_model(tf.keras.Sequential([
   quantize_annotate_layer(CustomLayer(20, input_shape=(20,)), DefaultDenseQuantizeConfig()),
   tf.keras.layers.Flatten()
]))

# `quantize_apply` requires mentioning `DefaultDenseQuantizeConfig` with `quantize_scope`
# as well as the custom Keras layer.
with quantize_scope(
  {'DefaultDenseQuantizeConfig': DefaultDenseQuantizeConfig,
   'CustomLayer': CustomLayer}):
  # Use `quantize_apply` to actually make the model quantization aware.
  quant_aware_model = tfmot.quantization.keras.quantize_apply(model)

quant_aware_model.summary()
Model: "sequential_8"
_________________________________________________________________
 Layer (type)                Output Shape              Param #   
=================================================================
 quantize_layer_6 (QuantizeL  (None, 20)               3         
 ayer)                                                           
                                                                 
 quant_custom_layer (Quantiz  (None, 20)               425       
 eWrapperV2)                                                     
                                                                 
 quant_flatten_9 (QuantizeWr  (None, 20)               1         
 apperV2)                                                        
                                                                 
=================================================================
Total params: 429
Trainable params: 420
Non-trainable params: 9
_________________________________________________________________

量子化パラメータを変更する

一般的な誤り:未満の32ビットにバイアスを量子化は、通常、あまりにも多くのモデルの精度を損ないます。

この例では、修正Denseその重みの代わりにデフォルトの8ビットに対して4ビットを使用する層。モデルの残りの部分は、引き続きAPIのデフォルトを使用します。

quantize_annotate_layer = tfmot.quantization.keras.quantize_annotate_layer
quantize_annotate_model = tfmot.quantization.keras.quantize_annotate_model
quantize_scope = tfmot.quantization.keras.quantize_scope

class ModifiedDenseQuantizeConfig(DefaultDenseQuantizeConfig):
    # Configure weights to quantize with 4-bit instead of 8-bits.
    def get_weights_and_quantizers(self, layer):
      return [(layer.kernel, LastValueQuantizer(num_bits=4, symmetric=True, narrow_range=False, per_axis=False))]

構成の適用は、「量子化を使用した実験」のユースケース全体で同じです。

model = quantize_annotate_model(tf.keras.Sequential([
   # Pass in modified `QuantizeConfig` to modify this Dense layer.
   quantize_annotate_layer(tf.keras.layers.Dense(20, input_shape=(20,)), ModifiedDenseQuantizeConfig()),
   tf.keras.layers.Flatten()
]))

# `quantize_apply` requires mentioning `ModifiedDenseQuantizeConfig` with `quantize_scope`:
with quantize_scope(
  {'ModifiedDenseQuantizeConfig': ModifiedDenseQuantizeConfig}):
  # Use `quantize_apply` to actually make the model quantization aware.
  quant_aware_model = tfmot.quantization.keras.quantize_apply(model)

quant_aware_model.summary()
Model: "sequential_9"
_________________________________________________________________
 Layer (type)                Output Shape              Param #   
=================================================================
 quantize_layer_7 (QuantizeL  (None, 20)               3         
 ayer)                                                           
                                                                 
 quant_dense_9 (QuantizeWrap  (None, 20)               425       
 perV2)                                                          
                                                                 
 quant_flatten_10 (QuantizeW  (None, 20)               1         
 rapperV2)                                                       
                                                                 
=================================================================
Total params: 429
Trainable params: 420
Non-trainable params: 9
_________________________________________________________________

レイヤーの一部を変更してクオンタイズします

この例では、修正Denseの活性化を量子化スキップする層を。モデルの残りの部分は、引き続きAPIのデフォルトを使用します。

quantize_annotate_layer = tfmot.quantization.keras.quantize_annotate_layer
quantize_annotate_model = tfmot.quantization.keras.quantize_annotate_model
quantize_scope = tfmot.quantization.keras.quantize_scope

class ModifiedDenseQuantizeConfig(DefaultDenseQuantizeConfig):
    def get_activations_and_quantizers(self, layer):
      # Skip quantizing activations.
      return []

    def set_quantize_activations(self, layer, quantize_activations):
      # Empty since `get_activaations_and_quantizers` returns
      # an empty list.
      return

構成の適用は、「量子化を使用した実験」のユースケース全体で同じです。

model = quantize_annotate_model(tf.keras.Sequential([
   # Pass in modified `QuantizeConfig` to modify this Dense layer.
   quantize_annotate_layer(tf.keras.layers.Dense(20, input_shape=(20,)), ModifiedDenseQuantizeConfig()),
   tf.keras.layers.Flatten()
]))

# `quantize_apply` requires mentioning `ModifiedDenseQuantizeConfig` with `quantize_scope`:
with quantize_scope(
  {'ModifiedDenseQuantizeConfig': ModifiedDenseQuantizeConfig}):
  # Use `quantize_apply` to actually make the model quantization aware.
  quant_aware_model = tfmot.quantization.keras.quantize_apply(model)

quant_aware_model.summary()
Model: "sequential_10"
_________________________________________________________________
 Layer (type)                Output Shape              Param #   
=================================================================
 quantize_layer_8 (QuantizeL  (None, 20)               3         
 ayer)                                                           
                                                                 
 quant_dense_10 (QuantizeWra  (None, 20)               423       
 pperV2)                                                         
                                                                 
 quant_flatten_11 (QuantizeW  (None, 20)               1         
 rapperV2)                                                       
                                                                 
=================================================================
Total params: 427
Trainable params: 420
Non-trainable params: 7
_________________________________________________________________

カスタム量子化アルゴリズムを使用する

tfmot.quantization.keras.quantizers.Quantizerクラスは、その入力に任意のアルゴリズムを適用することができます呼び出し可能です。

この例では、入力が重みである、と私たちは中に数学を適用FixedRangeQuantizer重みに__call__機能。代わりに、元の重み値を、出力のFixedRangeQuantizer今の重みを使用しているだろう何に渡されます。

quantize_annotate_layer = tfmot.quantization.keras.quantize_annotate_layer
quantize_annotate_model = tfmot.quantization.keras.quantize_annotate_model
quantize_scope = tfmot.quantization.keras.quantize_scope

class FixedRangeQuantizer(tfmot.quantization.keras.quantizers.Quantizer):
  """Quantizer which forces outputs to be between -1 and 1."""

  def build(self, tensor_shape, name, layer):
    # Not needed. No new TensorFlow variables needed.
    return {}

  def __call__(self, inputs, training, weights, **kwargs):
    return tf.keras.backend.clip(inputs, -1.0, 1.0)

  def get_config(self):
    # Not needed. No __init__ parameters to serialize.
    return {}


class ModifiedDenseQuantizeConfig(DefaultDenseQuantizeConfig):
    # Configure weights to quantize with 4-bit instead of 8-bits.
    def get_weights_and_quantizers(self, layer):
      # Use custom algorithm defined in `FixedRangeQuantizer` instead of default Quantizer.
      return [(layer.kernel, FixedRangeQuantizer())]

構成の適用は、「量子化を使用した実験」のユースケース全体で同じです。

model = quantize_annotate_model(tf.keras.Sequential([
   # Pass in modified `QuantizeConfig` to modify this `Dense` layer.
   quantize_annotate_layer(tf.keras.layers.Dense(20, input_shape=(20,)), ModifiedDenseQuantizeConfig()),
   tf.keras.layers.Flatten()
]))

# `quantize_apply` requires mentioning `ModifiedDenseQuantizeConfig` with `quantize_scope`:
with quantize_scope(
  {'ModifiedDenseQuantizeConfig': ModifiedDenseQuantizeConfig}):
  # Use `quantize_apply` to actually make the model quantization aware.
  quant_aware_model = tfmot.quantization.keras.quantize_apply(model)

quant_aware_model.summary()
Model: "sequential_11"
_________________________________________________________________
 Layer (type)                Output Shape              Param #   
=================================================================
 quantize_layer_9 (QuantizeL  (None, 20)               3         
 ayer)                                                           
                                                                 
 quant_dense_11 (QuantizeWra  (None, 20)               423       
 pperV2)                                                         
                                                                 
 quant_flatten_12 (QuantizeW  (None, 20)               1         
 rapperV2)                                                       
                                                                 
=================================================================
Total params: 427
Trainable params: 420
Non-trainable params: 7
_________________________________________________________________