Added outdims for some basic layers

src/layers/basic.jl

@@ -39,6 +39,17 @@ function Base.show(io::IO, c::Chain)
   print(io, ")")
 end
 
+"""
+    outdims(c::Chain, isize::Tuple)
+
+Calculate the output dimensions given the input dimensions, `isize`.
+
+```julia
+m = Chain(Conv((3, 3), 3 => 16), Conv((3, 3), 16 => 32))
+outdims(m, (10, 10)) == (6, 6)
+```
+"""
+outdims(c::Chain, isize::Tuple) = foldl(∘, map(l -> (x -> outdims(l, x)), c.layers))
 
 # This is a temporary and naive implementation
 # it might be replaced in the future for better performance
@@ -116,6 +127,19 @@ end
 (a::Dense{<:Any,W})(x::AbstractArray{<:AbstractFloat}) where {T <: Union{Float32,Float64}, W <: AbstractArray{T}} =
   a(T.(x))
 
+"""
+    outdims(l::Dense, isize)
+
+Calculate the output dimensions given the input dimensions, `isize`.
+
+```julia
+m = Dense(10, 5)
+outdims(m, (5, 2)) == (5,)
+outdims(m, (10,)) == (5,)
+```
+"""
+outdims(l::Dense, isize) = (size(l.W)[2],)
+
 """
     Diagonal(in::Integer)
 
@@ -145,6 +169,17 @@ function Base.show(io::IO, l::Diagonal)
   print(io, "Diagonal(", length(l.α), ")")
 end
 
+"""
+    outdims(l::Diagonal, isize)
+
+Calculate the output dimensions given the input dimensions, `isize`.
+
+```julia
+m = Diagonal(10)
+outdims(m, (10,)) == (10,)
+```
+"""
+outdims(l::Diagonal, isize) = (length(l.α),)
 
 """
     Maxout(over)

src/layers/conv.jl

@@ -1,5 +1,7 @@
 using NNlib: conv, ∇conv_data, depthwiseconv
 
+_convoutdims(isize, ksize, ssize, pad) = Int.(floor.((isize .- ksize .+ 2 .* pad) ./ ssize .+ 1))
+
 expand(N, i::Tuple) = i
 expand(N, i::Integer) = ntuple(_ -> i, N)
 """
@@ -68,6 +70,18 @@ end
 (a::Conv{<:Any,<:Any,W})(x::AbstractArray{<:Real}) where {T <: Union{Float32,Float64}, W <: AbstractArray{T}} =
   a(T.(x))
 
+"""
+    outdims(l::Conv, isize::Tuple)
+
+Calculate the output dimensions given the input dimensions, `isize`.
+
+```julia
+m = Conv((3, 3), 3 => 16)
+outdims(m, (10, 10)) == (8, 8)
+```
+"""
+outdims(l::Conv{N}, isize) where N = _convoutdims(isize, size(l.weight)[1:N], l.stride, l.pad[1:N])
+
 """
     ConvTranspose(size, in=>out)
     ConvTranspose(size, in=>out, relu)
@@ -140,6 +154,7 @@ end
 
 (a::ConvTranspose{<:Any,<:Any,W})(x::AbstractArray{<:Real}) where {T <: Union{Float32,Float64}, W <: AbstractArray{T}} =
   a(T.(x))
+
 """
     DepthwiseConv(size, in=>out)
     DepthwiseConv(size, in=>out, relu)
@@ -204,6 +219,18 @@ end
 (a::DepthwiseConv{<:Any,<:Any,W})(x::AbstractArray{<:Real}) where {T <: Union{Float32,Float64}, W <: AbstractArray{T}} =
   a(T.(x))
 
+"""
+    outdims(l::DepthwiseConv, isize::Tuple)
+
+Calculate the output dimensions given the input dimensions, `isize`.
+
+```julia
+m = DepthwiseConv((3, 3), 3 => 16)
+outdims(m, (10, 10)) == (8, 8)
+```
+"""
+outdims(l::DepthwiseConv{N}, isize) where N = _convoutdims(isize, size(l.weight)[1:N], l.stride, l.pad[1:N])
+
 """
     CrossCor(size, in=>out)
     CrossCor(size, in=>out, relu)
@@ -304,6 +331,18 @@ function Base.show(io::IO, m::MaxPool)
   print(io, "MaxPool(", m.k, ", pad = ", m.pad, ", stride = ", m.stride, ")")
 end
 
+"""
+    outdims(l::MaxPool, isize::Tuple)
+
+Calculate the output dimensions given the input dimensions, `isize`.
+
+```julia
+m = MaxPool((2, 2))
+outdims(m, (10, 10)) == (5, 5)
+```
+"""
+outdims(l::MaxPool{N}, isize) where N = _convoutdims(isize, l.weight, l.stride, l.pad[1:N])
+
 """
     MeanPool(k)
 
@@ -331,3 +370,15 @@ end
 function Base.show(io::IO, m::MeanPool)
   print(io, "MeanPool(", m.k, ", pad = ", m.pad, ", stride = ", m.stride, ")")
 end
+
+"""
+    outdims(l::MeanPool, isize::Tuple)
+
+Calculate the output dimensions given the input dimensions, `isize`.
+
+```julia
+m = MeanPool((2, 2))
+outdims(m, (10, 10)) == (5, 5)
+```
+"""
+outdims(l::MeanPool{N}, isize) where N = _convoutdims(isize, l.weight, l.stride, l.pad[1:N])