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    Python使用gluon/mxnet模块实现的mnist手写数字识别功能完整示例

    栏目:代码类 时间:2019-12-18 15:07

    本文实例讲述了Python使用gluon/mxnet模块实现的mnist手写数字识别功能。分享给大家供大家参考,具体如下:

    import gluonbook as gb
    from mxnet import autograd,nd,init,gluon
    from mxnet.gluon import loss as gloss,data as gdata,nn,utils as gutils
    import mxnet as mx
    net = nn.Sequential()
    with net.name_scope():
      net.add(
        nn.Conv2D(channels=32, kernel_size=5, activation='relu'),
        nn.MaxPool2D(pool_size=2, strides=2),
        nn.Flatten(),
        nn.Dense(128, activation='sigmoid'),
        nn.Dense(10, activation='sigmoid')
      )
    lr = 0.5
    batch_size=256
    ctx = mx.gpu()
    net.initialize(init=init.Xavier(), ctx=ctx)
    train_data, test_data = gb.load_data_fashion_mnist(batch_size)
    trainer = gluon.Trainer(net.collect_params(),'sgd',{'learning_rate' : lr})
    loss = gloss.SoftmaxCrossEntropyLoss()
    num_epochs = 30
    def train(train_data, test_data, net, loss, trainer,num_epochs):
      for epoch in range(num_epochs):
        total_loss = 0
        for x,y in train_data:
          with autograd.record():
            x = x.as_in_context(ctx)
            y = y.as_in_context(ctx)
            y_hat=net(x)
            l = loss(y_hat,y)
          l.backward()
          total_loss += l
          trainer.step(batch_size)
        mx.nd.waitall()
        print("Epoch [{}]: Loss {}".format(epoch, total_loss.sum().asnumpy()[0]/(batch_size*len(train_data))))
    if __name__ == '__main__':
      try:
        ctx = mx.gpu()
        _ = nd.zeros((1,), ctx=ctx)
      except:
        ctx = mx.cpu()
      ctx
      gb.train(train_data,test_data,net,loss,trainer,ctx,num_epochs)
    
    

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