Generic interface

All schedules must inherit from AbstractSchedule. Any concrete subtype must implement the iteration interface and Base.getindex. Below we reimplement Lambda to illustrate what is required for another generic custom schedule.

To avoid a name conflict, we will call our custom schedule FooSchedule. Let’s start with defining the struct.

using ParameterSchedulers

struct FooSchedule{T} <: ParameterSchedulers.AbstractSchedule
    f::T
end

Next we implement the necessary interfaces. The easiest implementation to define Base.getindex, then rely on that to define the iteration behavior.

Base.getindex(schedule::FooSchedule, t::Integer) = schedule.f(t)

Base.iterate(schedule::FooSchedule, t = 1) = (schedule[t], t + 1)

Info

By default, Base.firstindex(s::AbstractSchedule) == 1. This behavior is expected across ParameterSchedulers.jl, so your definition of Base.getindex should conform to that.

Tip

Sometimes, it might be more efficient to define Base.iterate separately from Base.getindex. See Step for an example what this might look like.

Apart to the behavioral methods, there are some additional functions in the iteration interface left to define.

Base.IteratorEltype(::Type{<:FooSchedule}) = Base.EltypeUnknown()
Base.IteratorSize(::Type{<:FooSchedule}) = Base.SizeUnkown()

In this case, the element type and length of the iterator is unknown, since f is unknown. But you can define more restricted return values for your iterator.

Once you are done defining the above interfaces, you can start using FooSchedule like any other schedule. For example, below we create a Loop where the interval is defined as a FooSchedule

using UnicodePlots

s = Loop(f = FooSchedule(log), period = 4)
t = 1:10 |> collect
lineplot(t, map(t -> s[t], t); border = :none)

 
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Tutorials

Interfaces

Generic interface