如何用数据集拟合 keras 模型？

Question

我尝试用一组 csv 文件来拟合我的 keras 模型（我不想在内存中加载文件并连接它们）。我试图用“tf.data.experimental.make_csv_dataset”构建一个数据集（我认为它像 matlab 数据存储一样工作？）并用“next”和“iter”为我的模型提供数据，但我无法解决输入大小 and/or 的问题输入类型。我将不胜感激任何帮助。提前致谢。

import tensorflow as tf
from tensorflow import keras
from tensorflow.keras.models import Sequential
from tensorflow.keras.layers import Dense


dataset = tf.data.experimental.make_csv_dataset(
    "data/Testdata/*.csv",
    batch_size=128,
    field_delim=",",
    num_epochs=1,
    select_columns=['A', 'B', 'C'],
    label_name='C')

# MLP Model
model = Sequential()
model.add(Dense(1, input_dim=5))  
model.add(Dense(5, activation='relu'))
model.add(Dense(1, activation='linear'))
model.summary()

model.compile(loss='mean_absolute_error', optimizer="adam", metrics=['mean_squared_error'])

# for batch in dataset:
X, y = next(iter(dataset))

res = model.fit(X, y, epochs=5)

Answer 1

您可以将数据集直接提供给 model.fit，并进行一些更改：

创建虚拟数据：

import pandas as pd
import tensorflow as tf
from tensorflow import keras
from tensorflow.keras.models import Sequential
from tensorflow.keras.layers import Dense


df = pd.DataFrame(data={'A': [50.1, 1.23, 4.5, 4.3, 3.2], 'B':[50.1, 1.23, 4.5, 4.3, 3.2], 'C':[5.2, 3.1, 2.2, 1., 3.]})

df.to_csv('data1.csv', index=False)
df.to_csv('data2.csv', index=False)

预处理数据：

dataset = tf.data.experimental.make_csv_dataset(
    "/content/*.csv",
    batch_size=2,
    field_delim=",",
    num_epochs=1,
    select_columns=['A', 'B', 'C'],
    label_name='C')

处理前：

for x in dataset:
  print(x)

OrderedDict([('A', <tf.Tensor: shape=(2,), dtype=float32, numpy=array([4.5 , 1.23], dtype=float32)>), ('B', <tf.Tensor: shape=(2,), dtype=float32, numpy=array([4.5 , 1.23], dtype=float32)>)]), <tf.Tensor: shape=(2,), dtype=float32, numpy=array([2.2, 3.1], dtype=float32)>)
(OrderedDict([('A', <tf.Tensor: shape=(2,), dtype=float32, numpy=array([50.1,  4.5], dtype=float32)>), ('B', <tf.Tensor: shape=(2,), dtype=float32, numpy=array([50.1,  4.5], dtype=float32)>)]), <tf.Tensor: shape=(2,), dtype=float32, numpy=array([5.2, 2.2], dtype=float32)>)
(OrderedDict([('A', <tf.Tensor: shape=(2,), dtype=float32, numpy=array([ 4.3, 50.1], dtype=float32)>), ('B', <tf.Tensor: shape=(2,), dtype=float32, numpy=array([ 4.3, 50.1], dtype=float32)>)]), <tf.Tensor: shape=(2,), dtype=float32, numpy=array([1. , 5.2], dtype=float32)>)
(OrderedDict([('A', <tf.Tensor: shape=(2,), dtype=float32, numpy=array([1.23, 4.3 ], dtype=float32)>), ('B', <tf.Tensor: shape=(2,), dtype=float32, numpy=array([1.23, 4.3 ], dtype=float32)>)]), <tf.Tensor: shape=(2,), dtype=float32, numpy=array([3.1, 1. ], dtype=float32)>)
(OrderedDict([('A', <tf.Tensor: shape=(2,), dtype=float32, numpy=array([3.2, 3.2], dtype=float32)>), ('B', <tf.Tensor: shape=(2,), dtype=float32, numpy=array([3.2, 3.2], dtype=float32)>)]), <tf.Tensor: shape=(2,), dtype=float32, numpy=array([3., 3.], dtype=float32)>)

请注意，make_csv_dataset 的参数 shuffle 默认设置为 True。这就是您可能会看到混合输出的原因。

预处理后输入数据具有来自 A 和 B 的 2 个特征：

dataset = dataset.map(lambda x, y: (tf.concat([tf.expand_dims(x['A'], axis=-1), tf.expand_dims(x['B'], axis=-1)], axis=-1), y))
for x in dataset:
  print(x)

(<tf.Tensor: shape=(2, 2), dtype=float32, numpy=
array([[4.5 , 4.5 ],
       [1.23, 1.23]], dtype=float32)>, <tf.Tensor: shape=(2,), dtype=float32, numpy=array([2.2, 3.1], dtype=float32)>)
(<tf.Tensor: shape=(2, 2), dtype=float32, numpy=
array([[4.3, 4.3],
       [4.3, 4.3]], dtype=float32)>, <tf.Tensor: shape=(2,), dtype=float32, numpy=array([1., 1.], dtype=float32)>)
(<tf.Tensor: shape=(2, 2), dtype=float32, numpy=
array([[ 1.23,  1.23],
       [50.1 , 50.1 ]], dtype=float32)>, <tf.Tensor: shape=(2,), dtype=float32, numpy=array([3.1, 5.2], dtype=float32)>)
(<tf.Tensor: shape=(2, 2), dtype=float32, numpy=
array([[50.1, 50.1],
       [ 3.2,  3.2]], dtype=float32)>, <tf.Tensor: shape=(2,), dtype=float32, numpy=array([5.2, 3. ], dtype=float32)>)
(<tf.Tensor: shape=(2, 2), dtype=float32, numpy=
array([[4.5, 4.5],
       [3.2, 3.2]], dtype=float32)>, <tf.Tensor: shape=(2,), dtype=float32, numpy=array([2.2, 3. ], dtype=float32)>)

训练您的模型：

model = Sequential()
model.add(Dense(1, input_dim=2))  
model.add(Dense(5, activation='relu'))
model.add(Dense(1, activation='linear'))
model.summary()

model.compile(loss='mean_absolute_error', optimizer="adam", metrics=['mean_squared_error'])

res = model.fit(dataset, epochs=5)

Model: "sequential_7"
_________________________________________________________________
 Layer (type)                Output Shape              Param #   
=================================================================
 dense_21 (Dense)            (None, 1)                 3         
                                                                 
 dense_22 (Dense)            (None, 5)                 10        
                                                                 
 dense_23 (Dense)            (None, 1)                 6         
                                                                 
=================================================================
Total params: 19
Trainable params: 19
Non-trainable params: 0
_________________________________________________________________
Epoch 1/5
5/5 [==============================] - 1s 21ms/step - loss: 10.2060 - mean_squared_error: 247.2872
Epoch 2/5
5/5 [==============================] - 0s 10ms/step - loss: 10.0791 - mean_squared_error: 241.0892
Epoch 3/5
5/5 [==============================] - 0s 8ms/step - loss: 9.9328 - mean_squared_error: 233.3316
Epoch 4/5
5/5 [==============================] - 0s 6ms/step - loss: 9.7714 - mean_squared_error: 224.4764
Epoch 5/5
5/5 [==============================] - 0s 8ms/step - loss: 9.6863 - mean_squared_error: 221.0282

如何用数据集拟合 keras 模型？

How to fit a keras model with a dataset?

python

dataset

keras

tensorflow

tensorflow-datasets

创建虚拟数据：

预处理数据：

处理前：

预处理后输入数据具有来自 A 和 B 的 2 个特征：

训练您的模型：