如何将Scikit-Learn-Keras模型保存到持久性文件中(pickle/hd5/json/yaml)

Question

我有以下代码,使用Keras Scikit-Learn Wrapper:

from keras.models import Sequential
from sklearn import datasets
from keras.layers import Dense
from sklearn.model_selection import train_test_split
from keras.wrappers.scikit_learn import KerasClassifier
from sklearn.model_selection import StratifiedKFold
from sklearn.model_selection import cross_val_score
from sklearn import preprocessing
import pickle
import numpy as np
import json

def classifier(X, y):
    """
    Description of classifier
    """
    NOF_ROW, NOF_COL =  X.shape

    def create_model():
        # create model
        model = Sequential()
        model.add(Dense(12, input_dim=NOF_COL, init='uniform', activation='relu'))
        model.add(Dense(6, init='uniform', activation='relu'))
        model.add(Dense(1, init='uniform', activation='sigmoid'))
        # Compile model
        model.compile(loss='binary_crossentropy', optimizer='adam', metrics=['accuracy'])
        return model

    # evaluate using 10-fold cross validation
    seed = 7
    np.random.seed(seed)
    model = KerasClassifier(build_fn=create_model, nb_epoch=150, batch_size=10, verbose=0)
    return model


def main():
    """
    Description of main
    """

    iris = datasets.load_iris()
    X, y = iris.data, iris.target
    X = preprocessing.scale(X)

    X_train, X_test, y_train, y_test = train_test_split(X, y, test_size=0.4, random_state=0)
    model_tt = classifier(X_train, y_train)
    model_tt.fit(X_train,y_train)

    #--------------------------------------------------
    # This fail
    #-------------------------------------------------- 
    filename = 'finalized_model.sav'
    pickle.dump(model_tt, open(filename, 'wb'))
    # load the model from disk
    loaded_model = pickle.load(open(filename, 'rb'))
    result = loaded_model.score(X_test, Y_test)
    print(result)

    #--------------------------------------------------
    # This also fail
    #--------------------------------------------------
    # from keras.models import load_model       
    # model_tt.save('test_model.h5')


    #--------------------------------------------------
    # This works OK 
    #-------------------------------------------------- 
    # print model_tt.score(X_test, y_test)
    # print model_tt.predict_proba(X_test)
    # print model_tt.predict(X_test)


# Output of predict_proba
# 2nd column is the probability that the prediction is 1
# this value is used as final score, which can be used
# with other method as comparison
# [   [ 0.25311464  0.74688536]
#     [ 0.84401423  0.15598579]
#     [ 0.96047372  0.03952631]
#     ...,
#     [ 0.25518912  0.74481088]
#     [ 0.91467732  0.08532269]
#     [ 0.25473493  0.74526507]]

# Output of predict
# [[1]
# [0]
# [0]
# ...,
# [1]
# [0]
# [1]]


if __name__ == '__main__':
    main()

如代码中所述,它在此行失败:

pickle.dump(model_tt, open(filename, 'wb'))

出现此错误:

pickle.PicklingError: Can't pickle <function create_model at 0x101c09320>: it's not found as __main__.create_model

我怎么能绕过它呢？

Answer 1

编辑1:关于保存模型的原始答案

使用HDF5:

# saving model
json_model = model_tt.model.to_json()
open('model_architecture.json', 'w').write(json_model)
# saving weights
model_tt.model.save_weights('model_weights.h5', overwrite=True)


# loading model
from keras.models import model_from_json

model = model_from_json(open('model_architecture.json').read())
model.load_weights('model_weights.h5')

# dont forget to compile your model
model.compile(loss='binary_crossentropy', optimizer='adam')

编辑2:使用虹膜数据集的完整代码示例

# Train model and make predictions
import numpy
import pandas
from keras.models import Sequential, model_from_json
from keras.layers import Dense
from keras.utils import np_utils
from sklearn import datasets
from sklearn import preprocessing
from sklearn.model_selection import train_test_split
from sklearn.preprocessing import LabelEncoder

# fix random seed for reproducibility
seed = 7
numpy.random.seed(seed)

# load dataset
iris = datasets.load_iris()
X, Y, labels = iris.data, iris.target, iris.target_names
X = preprocessing.scale(X)

# encode class values as integers
encoder = LabelEncoder()
encoder.fit(Y)
encoded_Y = encoder.transform(Y)

# convert integers to dummy variables (i.e. one hot encoded)
y = np_utils.to_categorical(encoded_Y)

def build_model():
    # create model
    model = Sequential()
    model.add(Dense(4, input_dim=4, init='normal', activation='relu'))
    model.add(Dense(3, init='normal', activation='sigmoid'))
    model.compile(loss='categorical_crossentropy', optimizer='adam', metrics=['accuracy'])
    return model

def save_model(model):
    # saving model
    json_model = model.to_json()
    open('model_architecture.json', 'w').write(json_model)
    # saving weights
    model.save_weights('model_weights.h5', overwrite=True)

def load_model():
    # loading model
    model = model_from_json(open('model_architecture.json').read())
    model.load_weights('model_weights.h5')
    model.compile(loss='categorical_crossentropy', optimizer='adam')
    return model


X_train, X_test, Y_train, Y_test = train_test_split(X, y, test_size=0.3, random_state=seed)

# build
model = build_model()
model.fit(X_train, Y_train, nb_epoch=200, batch_size=5, verbose=0)

# save
save_model(model)

# load
model = load_model()

# predictions
predictions = model.predict_classes(X_test, verbose=0)
print(predictions)
# reverse encoding
for pred in predictions:
    print(labels[pred])

请注意,我只使用了Keras,而不是包装器.它只会增加一些简单的复杂性.代码也是volontary没有因素,所以你可以拥有整个画面.

此外,你说你要输出1或0.这个数据集是不可能的,因为你有3个输出dims和类(Iris-setosa,Iris-versicolor,Iris-virginica).如果你只有2个类,那么你的输出变暗,使用sigmoid输出功能,类将为0或1.

Answer 2

只需添加gaarv的答案-如果您不需要模型结构（model.to_json()）和权重（model.save_weights()）之间的分隔，则可以使用以下选项之一：

• 使用keras.models.save_model将所有内容一起存储在hdf5文件中的内置和'keras.models.load_model`。
• 使用pickle将Model对象（或包含对其的引用的任何类）序列化到文件/网络/任何文件中。
  不幸的是，Keras默认情况下不支持pickle。您可以使用添加了此缺失功能的补丁解决方案。工作代码在这里：http: //zachmoshe.com/2017/04/03/pickling-keras-models.html

Answer 3

接受的答案太复杂了。您可以在.h5文件中完全保存和恢复模型的各个方面。直接来自Keras 常见问题解答：

您可以使用model.save(filepath)将 Keras 模型保存到单个 HDF5 文件中，该文件将包含：

• 模型的架构，允许重新创建模型
• 模型的权重
• 训练配置（损失，优化器）
• 优化器的状态，允许从您停止的地方恢复训练。

然后您可以使用它keras.models.load_model(filepath)来重新实例化您的模型。load_model还将负责使用保存的训练配置编译模型（除非模型从未编译过）。

以及相应的代码：

from keras.models import load_model

model.save('my_model.h5')  # creates a HDF5 file 'my_model.h5'
del model  # deletes the existing model

# returns a compiled model identical to the previous one
model = load_model('my_model.h5')

Answer 4

另一个很好的选择是在模型时使用回调fit。特别是ModelCheckpoint回调，如下所示：

from keras.callbacks import ModelCheckpoint
#Create instance of ModelCheckpoint
chk = ModelCheckpoint("myModel.h5", monitor='val_loss', save_best_only=False)
#add that callback to the list of callbacks to pass
callbacks_list = [chk]
#create your model
model_tt = KerasClassifier(build_fn=create_model, nb_epoch=150, batch_size=10)
#fit your model with your data. Pass the callback(s) here
model_tt.fit(X_train,y_train, callbacks=callbacks_list)

这会将您的训练每个纪元保存到myModel.h5文件中。这提供了很大的好处，因为您可以在需要时停止训练（例如，当您看到训练开始过度适应时），并且仍然保留以前的训练。

请注意，这会将结构和权重都保存在同一hdf5文件中（如Zach所示），因此您可以使用加载模型keras.models.load_model。

如果只想单独保存权重，则可以save_weights_only=True在实例化时使用参数ModelCheckpoint，从而使您能够按照Gaarv的说明加载模型。从文档中提取：

save_weights_only：如果为True，则仅保存模型的权重（model.save_weights（filepath）），否则保存完整模型（model.save（filepath））。