#!/usr/bin/env python2# -*- coding: utf-8 -*-"""Created on Fri Aug 10 16:13:29 2018@author: myhaspl"""from mxnet import nd, gluon, init, autogradfrom mxnet.gluon import nnfrom mxnet.gluon.data.vision import datasets,transforms import matplotlib.pyplot as pltfrom time import timemnist_train = datasets.FashionMNIST(train=True)X, y = mnist_train[0]print (‘X shape: ‘, X.shape, ‘X dtype‘, X.dtype, ‘y:‘, y,‘Y dtype‘, y.dtype)#x:(height, width, channel)#y:numpy.scalar，标签text_labels = [ ???????????‘t-shirt‘, ‘trouser‘, ‘pullover‘, ‘dress‘, ‘coat‘, ???????????‘sandal‘, ‘shirt‘, ‘sneaker‘, ‘bag‘, ‘ankle boot‘]X, y = mnist_train[0:6]#取6个样本_, figs = plt.subplots(1, X.shape[0], figsize=(15, 15))for f,x,yi in zip(figs, X,y): ???# 3D->2D by removing the last channel dim ???f.imshow(x.reshape((28,28)).asnumpy()) ???ax = f.axes ???ax.set_title(text_labels[int(yi)]) ???ax.title.set_fontsize(20) ???ax.get_xaxis().set_visible(False) ???ax.get_yaxis().set_visible(False)plt.show()#转换图像为(channel, height, weight)格式，并且为floating数据类型，通过transforms.ToTensor。#另外，normalize所有像素值 使用 transforms.Normalize平均值0.13和标准差0.31. transformer = transforms.Compose([ ???????????transforms.ToTensor(), ???????????transforms.Normalize(0.13, 0.31)])#只转换第一个元素，图像部分。第二个元素为标签。mnist_train = mnist_train.transform_first(transformer)#加载批次数据batch_size = 200train_data = gluon.data.DataLoader(mnist_train, batch_size=batch_size, shuffle=True, num_workers=4)#读取本批数据i=1for data, label in train_data: ???print i ???print data,label ???break#没有这一行，会以每批次200个数据来读取。mnist_valid = gluon.data.vision.FashionMNIST(train=False)valid_data = gluon.data.DataLoader(mnist_valid.transform_first(transformer),batch_size=batch_size, num_workers=4)#定义网络net = nn.Sequential()net.add(nn.Conv2D(channels=6,kernel_size=5,activation="relu"), ???????nn.MaxPool2D(pool_size=2, strides=2), ???????nn.Conv2D(channels=16, kernel_size=3, activation="relu"), ???????nn.MaxPool2D(pool_size=2, strides=2), ???????nn.Flatten(), ???????nn.Dense(120, activation="relu"), ???????nn.Dense(84, activation="relu"), ???????nn.Dense(10))net.initialize(init=init.Xavier())print net#输出softmax与误差softmax_cross_entropy = gluon.loss.SoftmaxCrossEntropyLoss()#定义训练器trainer = gluon.Trainer(net.collect_params(), ‘sgd‘, {‘learning_rate‘: 0.1})-0.41935483
? ? -0.41935483]
? ?[-0.41935483 -0.41935483 -0.41935483 ... -0.41935483 -0.41935483
? ? -0.41935483]]]]
<NDArray 200x1x28x28 @cpu_shared(0)>?
[9 0 9 ... 3 8 5]
<NDArray 200 @cpu_shared(0)>
Sequential(
? (0): Conv2D(None -> 6, kernel_size=(5, 5), stride=(1, 1))
? (1): MaxPool2D(size=(2, 2), stride=(2, 2), padding=(0, 0), ceil_mode=False)
? (2): Conv2D(None -> 16, kernel_size=(3, 3), stride=(1, 1))
? (3): MaxPool2D(size=(2, 2), stride=(2, 2), padding=(0, 0), ceil_mode=False)
? (4): Flatten
? (5): Dense(None -> 120, Activation(relu))
? (6): Dense(None -> 84, Activation(relu))
? (7): Dense(None -> 10, linear)
)
mxnet-训练器与分批读取样本
原文地址：http://blog.51cto.com/13959448/2317239