https://blog.csdn.net/houchaoqun_xmu/article/details/78492718
前言:
keras 源码中下载MNIST的方式是 path = get_file(path, origin='https://s3.amazonaws.com/img-datasets/mnist.npz'),数据源是通过 url = https://s3.amazonaws.com/img-datasets/mnist.npz 进行下载的。访问该 url 地址被墙了,导致 MNIST 相关的案例都卡在数据下载的环节。本文主要提供解决方案,让需要的读者可以跑案例的代码感受一下。
本文的贡献主要包括如下:
1)提供 mnist_npz 数据集;
2)分析了关于 mnist 几个相关的源代码;
3)提供了一种能够顺利运行 keras 源码中 example 下 mnist 的相关案例;
4)找到了另外几种解决方案,提供了相关的链接。
numpy.load(path)
numpy.load() 函数起到很重要的作用。它可以读取 .npy .npz 等文件类型,并返回对应的数据类型。
1)如果文件类型是 .pny 则返回一个1维数组。
2)如果文件类型是 .npz 则返回一个类似字典的数据类型,包含 {filename: array} 键值对。如,本例中的键值对如下所示:
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f = np.load(path)
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x_train, y_train = f['x_train'], f['y_train']
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x_test, y_test = f['x_test'], f['y_test']
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f.close()
详情请参考:https://docs.scipy.org/doc/numpy/reference/generated/numpy.load.html
原始 .\keras\examples\mnist_mlp.py
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# -*- coding: utf-8 -*-
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'''Trains a simple deep NN on the MNIST dataset.
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Gets to 98.40% test accuracy after 20 epochs
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(there is *a lot* of margin for parameter tuning).
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2 seconds per epoch on a K520 GPU.
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'''
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from __future__ import print_function
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import keras
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from keras.datasets import mnist
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from keras.models import Sequential
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from keras.layers import Dense, Dropout
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from keras.optimizers import RMSprop
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batch_size = 128
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num_classes = 10
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epochs = 20
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# the data, shuffled and split between train and test sets
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(x_train, y_train), (x_test, y_test) = mnist.load_data()
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x_train = x_train.reshape(60000, 784)
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x_test = x_test.reshape(10000, 784)
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x_train = x_train.astype('float32')
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x_test = x_test.astype('float32')
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x_train /= 255
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x_test /= 255
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print(x_train.shape[0], 'train samples')
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print(x_test.shape[0], 'test samples')
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# convert class vectors to binary class matrices
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y_train = keras.utils.to_categorical(y_train, num_classes)
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y_test = keras.utils.to_categorical(y_test, num_classes)
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model = Sequential()
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model.add(Dense(512, activation='relu', input_shape=(784,)))
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model.add(Dropout(0.2))
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model.add(Dense(512, activation='relu'))
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model.add(Dropout(0.2))
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model.add(Dense(10, activation='softmax'))
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model.summary()
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###
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# 1)categorical_crossentropy(output, target, from_logits=False):
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# 计算输出张量和目标张量的Categorical crossentropy(类别交叉熵),目标张量与输出张量必须shape相同。
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# 多分类的对数损失函数,与softmax分类器相对应的。
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#
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# 2)RMSprop()
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# AdaGrad算法的改进。鉴于神经网络都是非凸条件下的,RMSProp在非凸条件下结果更好,改变梯度累积为指数衰减的移动平均以丢弃遥远的过去历史。
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# reference:http://blog.csdn.net/bvl10101111/article/details/72616378
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#
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model.compile(loss='categorical_crossentropy',
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optimizer=RMSprop(),
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metrics=['accuracy'])
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history = model.fit(x_train, y_train,
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batch_size=batch_size,
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epochs=epochs,
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verbose=1,
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validation_data=(x_test, y_test))
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score = model.evaluate(x_test, y_test, verbose=0)
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print('Test loss:', score[0])
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print('Test accuracy:', score[1])
.\keras\keras\datasets\mnist.py - load_data()
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# -*- coding: utf-8 -*-
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from ..utils.data_utils import get_file
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import numpy as np
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def load_data(path='mnist.npz'):
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"""Loads the MNIST dataset.
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# Arguments
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path: path where to cache the dataset locally
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(relative to ~/.keras/datasets).
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# Returns
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Tuple of Numpy arrays: `(x_train, y_train), (x_test, y_test)`.
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# numpy.load()
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# numpy.load(file, mmap_mode=None, allow_pickle=True, fix_imports=True, encoding='ASCII')
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# 1) Load arrays or pickled objects from .npy, .npz or pickled files
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# 2)
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# reference: https://docs.scipy.org/doc/numpy/reference/generated/numpy.load.html
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"""
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path = get_file(path, origin='https://s3.amazonaws.com/img-datasets/mnist.npz')
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f = np.load(path)
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x_train, y_train = f['x_train'], f['y_train']
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x_test, y_test = f['x_test'], f['y_test']
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f.close()
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return (x_train, y_train), (x_test, y_test)
下载 mnist.npz 数据集
本文使用的 mnist.npz 数据集是通过一个 japan 的服务器下载得到的,在此免费分享给大家。如果下载有问题的话,可以留言哈。
下载链接:https://pan.baidu.com/s/1jH6uFFC 密码: dw3d
改造 mnist_mlp.py
方法1:
mnist_mlp.py 源码是使用如下命令获取数据集:
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# the data, shuffled and split between train and test sets
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(x_train, y_train), (x_test, y_test) = mnist.load_data()
调用的是 .\keras\keras\datasets\mnist.py 脚本中的 def load_data(path='mnist.npz') 函数,也就是因为网址被墙了导致不能正常运行的原因。本文事先下好了 mnist.npz 数据集,然后改动了一些代码使之正常运行。换句话说,本文使用的是“读取本地数据集”的方法,步骤如下:
1)下载好 mnist_npz 数据集,并将其放于 .\keras\examples 目录下。
2)改动后的 mnist_mlp.py 代码如下:
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# -*- coding: utf-8 -*-
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'''Trains a simple deep NN on the MNIST dataset.
-
-
Gets to 98.40% test accuracy after 20 epochs
-
(there is *a lot* of margin for parameter tuning).
-
2 seconds per epoch on a K520 GPU.
-
'''
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from __future__ import print_function
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import keras
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from keras.datasets import mnist
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from keras.models import Sequential
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from keras.layers import Dense, Dropout
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from keras.optimizers import RMSprop
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batch_size = 128
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num_classes = 10
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epochs = 20
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# the data, shuffled and split between train and test sets
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# (x_train, y_train), (x_test, y_test) = mnist.load_data()
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import numpy as np
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path='./mnist.npz'
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f = np.load(path)
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x_train, y_train = f['x_train'], f['y_train']
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x_test, y_test = f['x_test'], f['y_test']
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f.close()
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x_train = x_train.reshape(60000, 784).astype('float32')
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x_test = x_test.reshape(10000, 784).astype('float32')
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x_train /= 255
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x_test /= 255
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print(x_train.shape[0], 'train samples')
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print(x_test.shape[0], 'test samples')
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# convert class vectors to binary class matrices
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# label为0~9共10个类别,keras要求格式为binary class matrices
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y_train = keras.utils.to_categorical(y_train, num_classes)
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y_test = keras.utils.to_categorical(y_test, num_classes)
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# add by hcq-20171106
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# Dense of keras is full-connection.
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model = Sequential()
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model.add(Dense(512, activation='relu', input_shape=(784,)))
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model.add(Dropout(0.2))
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model.add(Dense(512, activation='relu'))
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model.add(Dropout(0.2))
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model.add(Dense(num_classes, activation='softmax'))
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model.summary()
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model.compile(loss='categorical_crossentropy',
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optimizer=RMSprop(),
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metrics=['accuracy'])
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history = model.fit(x_train, y_train,
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batch_size=batch_size,
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epochs=epochs,
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verbose=1,
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validation_data=(x_test, y_test))
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score = model.evaluate(x_test, y_test, verbose=0)
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print('Test loss:', score[0])
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print('Test accuracy:', score[1])
运行效果如下所示:
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60000 train samples
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10000 test samples
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_________________________________________________________________
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Layer (type) Output Shape Param #
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=================================================================
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dense_1 (Dense) (None, 512) 401920
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_________________________________________________________________
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dropout_1 (Dropout) (None, 512) 0
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_________________________________________________________________
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dense_2 (Dense) (None, 512) 262656
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_________________________________________________________________
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dropout_2 (Dropout) (None, 512) 0
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_________________________________________________________________
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dense_3 (Dense) (None, 10) 5130
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=================================================================
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Total params: 669,706
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Trainable params: 669,706
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Non-trainable params: 0
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_________________________________________________________________
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Train on 60000 samples, validate on 10000 samples
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Epoch 1/20
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2017-11-09 23:06:16.881800: I tensorflow/core/common_runtime/gpu/gpu_device.cc:977] Creating TensorFlow device (/gpu:0) -> (device: 0, name: GeForce GTX 1080 Ti, pci bus id: 0000:01:00.0)
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60000/60000 [==============================] - 1s 23us/step - loss: 0.0387 - acc: 0.9888 - val_loss: 0.0706 - val_acc: 0.9814
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Epoch 8/20
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60000/60000 [==============================] - 1s 23us/step - loss: 0.0341 - acc: 0.9899 - val_loss: 0.0789 - val_acc: 0.9827
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Epoch 9/20
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60000/60000 [==============================] - 1s 23us/step - loss: 0.0304 - acc: 0.9911 - val_loss: 0.0851 - val_acc: 0.9833
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Epoch 10/20
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60000/60000 [==============================] - 1s 23us/step - loss: 0.0290 - acc: 0.9918 - val_loss: 0.0867 - val_acc: 0.9818
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Epoch 11/20
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60000/60000 [==============================] - 1s 23us/step - loss: 0.0264 - acc: 0.9924 - val_loss: 0.0881 - val_acc: 0.9833
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Epoch 12/20
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60000/60000 [==============================] - 1s 23us/step - loss: 0.0261 - acc: 0.9928 - val_loss: 0.1095 - val_acc: 0.9801
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Epoch 13/20
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60000/60000 [==============================] - 1s 23us/step - loss: 0.0246 - acc: 0.9931 - val_loss: 0.1012 - val_acc: 0.9830
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Epoch 14/20
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60000/60000 [==============================] - 1s 23us/step - loss: 0.0233 - acc: 0.9935 - val_loss: 0.1116 - val_acc: 0.9812
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Epoch 15/20
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60000/60000 [==============================] - 1s 23us/step - loss: 0.0223 - acc: 0.9942 - val_loss: 0.1016 - val_acc: 0.9832
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Epoch 16/20
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60000/60000 [==============================] - 1s 23us/step - loss: 0.0214 - acc: 0.9943 - val_loss: 0.1053 - val_acc: 0.9832
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Epoch 17/20
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60000/60000 [==============================] - 1s 23us/step - loss: 0.0178 - acc: 0.9950 - val_loss: 0.1095 - val_acc: 0.9838
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Epoch 18/20
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60000/60000 [==============================] - 1s 23us/step - loss: 0.0212 - acc: 0.9949 - val_loss: 0.1158 - val_acc: 0.9822
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Epoch 19/20
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60000/60000 [==============================] - 1s 23us/step - loss: 0.0197 - acc: 0.9951 - val_loss: 0.1112 - val_acc: 0.9831
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Epoch 20/20
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60000/60000 [==============================] - 1s 23us/step - loss: 0.0203 - acc: 0.9951 - val_loss: 0.1097 - val_acc: 0.9833
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Test loss: 0.109655842465
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Test accuracy: 0.9833
方法2:参考该【博文】
(x_train, y_train), (x_test, y_test) = mnist.load_data(path='/home/duchao/下载/mnist.npz')
Reference:
keras 中文文档:http://keras-cn.readthedocs.io/en/latest/
阅读源码遇到的一些TF、keras函数及问题:http://blog.csdn.net/jsliuqun/article/details/64444302
python读取mnist数据集:https://blog.mythsman.com/2016/01/25/1/
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