neural_network_mnist.jl

# this is from https://github.com/FluxML/model-zoo/blob/master/vision/mnist/mlp.jl

# This is pretty slow so run at own risk


using Flux, Flux.Data.MNIST, Statistics
using Flux: onehotbatch, onecold, crossentropy, throttle
using Base.Iterators: repeated
# using CuArrays

# Classify MNIST digits with a simple multi-layer-perceptron

imgs = MNIST.images()
# Stack images into one large batch
X = hcat(float.(reshape.(imgs, :))...)

labels = MNIST.labels()
# One-hot-encode the labels
Y = onehotbatch(labels, 0:9)

m = Chain(
  Dense(28^2, 32, relu),
  Dense(32, 10),
  softmax)

loss(x, y) = crossentropy(m(x), y)

accuracy(x, y) = mean(onecold(m(x)) .== onecold(y))

dataset = repeated((X, Y), 200)
evalcb = () -> @show(loss(X, Y))
opt = ADAM()


Flux.train!(loss, Flux.params(m), dataset, opt, cb = throttle(evalcb, 10))

accuracy(X, Y)

# Test set accuracy
tX = hcat(float.(reshape.(MNIST.images(:test), :))...)
tY = onehotbatch(MNIST.labels(:test), 0:9)

accuracy(tX, tY)