如何使用 KFold 交叉验证输出作为 CNN 输入进行图像处理？

Question

我正在尝试使用卷积神经网络（CNN）进行图像分类。我想使用 KFold 交叉验证进行数据训练和测试。我是新手，我真的不明白该怎么做。

我已经在单独的代码中尝试过 KFold 交叉验证和 CNN。而且我不知道如何将其结合起来。

我使用 iris_data.csv 和 3 个类作为输入示例。

import pandas as pd
import numpy as np
from sklearn.model_selection import KFold
from sklearn.preprocessing import MinMaxScaler
from sklearn.svm import SVR

dataset = pd.read_csv('iris_data.csv')

x = dataset.iloc[:,0:3]
y = dataset.iloc[:, 4]

scaler = MinMaxScaler(feature_range=(0, 1))
x = scaler.fit_transform(x)

cv = KFold(n_splits=10, shuffle=False)
for train_index, test_index in cv.split(x):
    print("Train Index: ", train_index, "\n")
    print("Test Index: ", test_index)

    x_train, x_test, y_train, y_test = x[train_index], x[test_index], y[train_index], y[test_index]

这里是 CNN 代码示例。

import numpy as np
import tensorflow as tf
from keras.models import Model
from keras.layers import Input, Activation, Dense, Conv2D, MaxPooling2D, Flatten
from keras.preprocessing.image import ImageDataGenerator
from keras.optimizers import Adam
from keras.callbacks import TensorBoard

# Images Dimensions
img_width, img_height = 200, 200

# Data Path
train_data_dir = 'data/train'
validation_data_dir = 'data/validation'

# Parameters
nb_train_samples = 100
nb_validation_samples = 50
epochs = 50
batch_size = 10

# TensorBoard Callbacks
callbacks = TensorBoard(log_dir='./Graph')

# Training Data Augmentation
train_datagen = ImageDataGenerator(
    rescale=1. / 255,
    shear_range=0.2,
    zoom_range=0.2,
    horizontal_flip=True)

# Rescale Testing Data
test_datagen = ImageDataGenerator(rescale=1. / 255)

# Train Data Generator
train_generator = train_datagen.flow_from_directory(
    train_data_dir,
    target_size=(img_width, img_height),
    batch_size=batch_size,
    class_mode='categorical')

# Testing Data Generator
validation_generator = test_datagen.flow_from_directory(
    validation_data_dir,
    target_size=(img_width, img_height),
    batch_size=batch_size,
    class_mode='categorical')

# Feature Extraction Layer KorNet
inputs = Input(shape=(img_width, img_height, 3))
conv_layer = Conv2D(16, (5, 5), strides=(3,3), activation='relu')(inputs) 
conv_layer = MaxPooling2D((2, 2))(conv_layer) 
conv_layer = Conv2D(32, (5, 5), strides=(3,3), activation='relu')(conv_layer) 
conv_layer = MaxPooling2D((2, 2))(conv_layer) 

# Flatten Layer
flatten = Flatten()(conv_layer) 

# Fully Connected Layer
fc_layer = Dense(32, activation='relu')(flatten)
outputs = Dense(3, activation='softmax')(fc_layer)

model = Model(inputs=inputs, outputs=outputs)

# Adam Optimizer and Cross Entropy Loss
adam = Adam(lr=0.0001)
model.compile(optimizer=adam, loss='categorical_crossentropy', metrics=['accuracy'])

# Print Model Summary
print(model.summary())

model.fit_generator(
    train_generator,
    steps_per_epoch=nb_train_samples // batch_size,
    epochs=epochs,
    validation_data=validation_generator,
    validation_steps=nb_validation_samples // batch_size, 
    callbacks=[callbacks])

model.save('./models/model.h5')
model.save_weights('./models/weights.h5')

我希望将 KFold 交叉验证的结果用作 CNN 的训练和测试数据。

Answer 1

就做这样的事情

from keras.models import Sequential
from sklearn.model_selection import KFold
import numpy

dataset = numpy.loadtxt("iris_data.csv", delimiter=",")
# split into input (X) and output (Y) variables
X = dataset[:,0:3]
Y = dataset[:,4]
# define 10-fold cross validation test harness
kfold = KFold(n_splits=10, shuffle=True, random_state=seed)
cvscores = []
for train, test in kfold.split(X, Y):
  # create model
    model = Sequential()
    model.add(Dense(12, input_dim=8, activation='relu'))
    .
    .
    .
    # Compile model
    model.compile(loss='categorical_crossentropy', optimizer='adam', metrics=['accuracy'])
    # Fit the model
    model.fit(X[train], Y[train], epochs=150, batch_size=10, verbose=0)
    # evaluate the model
    scores = model.evaluate(X[test], Y[test], verbose=0)
    print("%s: %.2f%%" % (model.metrics_names[1], scores[1]*100))
    cvscores.append(scores[1] * 100)
print("%.2f%% (+/- %.2f%%)" % (numpy.mean(cvscores), numpy.std(cvscores)))

看到这个https://machinelearningmastery.com/evaluate-performance-deep-learning-models-keras/