I’m trying to understand parametric types and parametric methods with a simple example.
I have some discrete data w with some metadata t.
All I want to show is how many times different metadata values pop up for various values of w.
struct myunit{W<:Integer,T<:Integer}
w::W
t::T
end
function getNWK(d::AbstractArray{T},l::AbstractArray{U},k::Integer) where {T<:myunit,U<:Integer}
nwk = zeros(k,length(l))
for i in 1:length(d)
nwk[d[i].t,d[i].w] += 1
end
nwk
end
@code_warntype
l = [1:100;]
x = rand(1:100,1000)
y = rand(1:3,1000)
arr = myunit.(x,y)
@code_warntype getNWK(arr,l)
Variables
#self#::Core.Compiler.Const(getNWK, false)
d::Array{myunit{Int64,Int64},1}
l::Array{Int64,1}
nwk::Array{Float64,1}
@_5::Union{Nothing, Tuple{Int64,Int64}}
i::Int64
Body::Array{Float64,1}
1 ─ %1 = Main.length(l)::Int64
│ (nwk = Main.zeros(%1))
│ %3 = Main.length(d)::Int64
│ %4 = (1:%3)::Core.Compiler.PartialStruct(UnitRange{Int64}, Any[Core.Compiler.Const(1, false), Int64])
│ (@_5 = Base.iterate(%4))
│ %6 = (@_5 === nothing)::Bool
│ %7 = Base.not_int(%6)::Bool
└── goto #4 if not %7
2 ┄ %9 = @_5::Tuple{Int64,Int64}::Tuple{Int64,Int64}
│ (i = Core.getfield(%9, 1))
│ %11 = Core.getfield(%9, 2)::Int64
│ %12 = Base.getindex(d, i)::myunit{Int64,Int64}
│ %13 = Base.getproperty(%12, :t)::Int64
│ %14 = Base.getindex(d, i)::myunit{Int64,Int64}
│ %15 = Base.getproperty(%14, :w)::Int64
│ %16 = Base.getindex(nwk, %13, %15)::Float64
│ %17 = (%16 + 1)::Float64
│ Base.setindex!(nwk, %17, %13, %15)
│ (@_5 = Base.iterate(%4, %11))
│ %20 = (@_5 === nothing)::Bool
│ %21 = Base.not_int(%20)::Bool
└── goto #4 if not %21
3 ─ goto #2
4 ┄ return nwk
Line 5 of the @code_warntype output was highlighted in yellow:
@_5::Union{Nothing, Tuple{Int64,Int64}}
I’m still getting the hang of @code_warntype but it appears to be concerned that if k is 0 then the output array will have no rows, how do I tell the compiler that this will never happen?