在进行mnist识别时,https://www.charleychai.com/blogs/2018/ai/NN/lenet.html中,
X_train = X_train.reshape(-1, 28, 28, 1)
X_test = X_test.reshape(-1, 28, 28, 1)
为什么要设置最后一维为1呢?
可以查看Conv2D中对input_shape的说明,https://keras.io/layers/convolutional/
Input shape
4D tensor with shape: (batch, channels, rows, cols)
if data_format
is "channels_first"
or 4D tensor with shape: (batch, rows, cols, channels)
if data_format
is "channels_last"
.
对于代码中,-1是指batch,共有多少个样本,28分别指rows和cols,最后一个是指通道数,由于不是RGB,所以是1。