Keras fit_generator给出尺寸不匹配错误 [英] Keras fit_generator gives a dimension mismatch error
问题描述
我正在研究MNIST数据集,其中X_train = (42000,28,28,1)
是训练集. y_train = (42000,10)
是相应的标签集.现在,我使用Keras从图像生成器创建一个迭代器,如下所示;
I am working on MNIST dataset, in which X_train = (42000,28,28,1)
is the training set. y_train = (42000,10)
is the corresponding label set. Now I create an iterator from the image generator using Keras as follows;
iter=datagen.flow(X_train,y_train,batch_size=32)
效果很好.
然后我使用训练模型;
Then I train the model using;
model.fit_generator(iter,steps_per_epoch=len(X_train)/32,epochs=1)
此处显示以下错误;
ValueError: Error when checking input: expected dense_9_input to have 2 dimensions, but got array with shape (32, 28, 28, 1)
我尝试过但未能找到错误.我也在这里搜索,但没有答案:
I tried but failed to find the mistake. Also I searched here but there was no answer:
预计density_218_input具有2维,但数组的形状为(512,28,28,1)
顺便说一下,这是我的模型摘要
BTW this is the summary of my model
请帮助我.
更新:
model=Sequential()
model.add(Dense(256,activation='relu',kernel_initializer='he_normal',input_shape=(28,28,1)))
model.add(Flatten())
model.add(Dense(10,activation='softmax',kernel_initializer='he_normal'))
推荐答案
形状不匹配是根本原因.输入形状与ImageDataGenetor
的预期不匹配.请检查以下示例中的mnist
数据.我用过Tensorflow 2.1
.
Shape mismatch was the root-cause. Input shape was not matching with what ImageDataGenetor
expects. Please check the following example with mnist
data. I have used Tensorflow 2.1
.
import tensorflow as tf
from tensorflow.keras.preprocessing.image import ImageDataGenerator
mnist = tf.keras.datasets.mnist
(x_train, y_train),(x_test, y_test) = mnist.load_data()
x_train, x_test = x_train / 255.0, x_test / 255.0
x_train = tf.expand_dims(x_train,axis=-1)
x_test = tf.expand_dims(x_test,axis=-1)
datagen = ImageDataGenerator(
rotation_range=40,
width_shift_range=0.2,
height_shift_range=0.2,
shear_range=0.2,
zoom_range=0.2)
iter=datagen.flow(x_train,y_train,batch_size=32)
model = tf.keras.models.Sequential([
tf.keras.layers.Flatten(input_shape=(28, 28,1)),
tf.keras.layers.Dense(128, activation='relu'),
tf.keras.layers.Dropout(0.2),
tf.keras.layers.Dense(10, activation='softmax')
])
model.compile(optimizer='adam',
loss='sparse_categorical_crossentropy',
metrics=['accuracy'])
#model.fit_generator(iter,steps_per_epoch=len(X_train)/32,epochs=1) # deprecated in TF2.1
model.fit_generator(iter,steps_per_epoch=len(iter),epochs=1)
model.evaluate(x_test, y_test)
完整代码为此处
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