81 lines
1.7 KiB
Julia
81 lines
1.7 KiB
Julia
"""
|
||
Chain(layers...)
|
||
|
||
Chain multiple layers / functions together, so that they are called in sequence
|
||
on a given input.
|
||
|
||
```julia
|
||
m = Chain(x -> x^2, x -> x+1)
|
||
m(5) == 26
|
||
|
||
m = Chain(Dense(10, 5), Dense(5, 2))
|
||
x = rand(10)
|
||
m(x) == m[2](m[1](x))
|
||
```
|
||
|
||
`Chain` also supports indexing and slicing, e.g. `m[2]` or `m[1:end-1]`.
|
||
`m[1:3](x)` will calculate the output of the first three layers.
|
||
"""
|
||
type Chain
|
||
layers::Vector{Any}
|
||
Chain(xs...) = new([xs...])
|
||
end
|
||
|
||
@forward Chain.layers Base.getindex, Base.first, Base.last, Base.endof, Base.push!
|
||
@forward Chain.layers Base.start, Base.next, Base.done
|
||
|
||
children(c::Chain) = c.layers
|
||
mapchildren(f, c::Chain) = Chain(f.(c.layers)...)
|
||
|
||
(s::Chain)(x) = foldl((x, m) -> m(x), x, s.layers)
|
||
|
||
Base.getindex(c::Chain, i::AbstractArray) = Chain(c.layers[i]...)
|
||
|
||
function Base.show(io::IO, c::Chain)
|
||
print(io, "Chain(")
|
||
join(io, c.layers, ", ")
|
||
print(io, ")")
|
||
end
|
||
|
||
"""
|
||
Dense(in::Integer, out::Integer, σ = identity)
|
||
|
||
Creates a traditional `Dense` layer with parameters `W` and `b`.
|
||
|
||
y = σ.(W * x .+ b)
|
||
|
||
The input `x` must be a vector of length `in`, or a batch of vectors represented
|
||
as an `in × N` matrix. The out `y` will be a vector or batch of length `out`.
|
||
|
||
```julia
|
||
julia> d = Dense(5, 2)
|
||
Dense(5, 2)
|
||
|
||
julia> d(rand(5))
|
||
Tracked 2-element Array{Float64,1}:
|
||
0.00257447
|
||
-0.00449443
|
||
```
|
||
"""
|
||
struct Dense{F,S,T}
|
||
σ::F
|
||
W::S
|
||
b::T
|
||
end
|
||
|
||
Dense(in::Integer, out::Integer, σ = identity; init = initn) =
|
||
Dense(σ, param(init(out, in)), param(init(out)))
|
||
|
||
treelike(Dense)
|
||
|
||
function (a::Dense)(x)
|
||
W, b, σ = a.W, a.b, a.σ
|
||
σ.(W*x .+ b)
|
||
end
|
||
|
||
function Base.show(io::IO, l::Dense)
|
||
print(io, "Dense(", size(l.W, 2), ", ", size(l.W, 1))
|
||
l.σ == identity || print(io, ", ", l.σ)
|
||
print(io, ")")
|
||
end
|