Identification of sub time structures

[JulStraus]

Problem statement

In the current stage, we do not know what time structures are within the top time structure, even when considering the parametric input.

Consider the following example:

using TimeStruct
# Creation of the time structure
day = SimpleTimes(24, 1);
opscen_summer = OperationalScenarios(2, [day, day], [0.5, 0.5]);
opscen_winter = OperationalScenarios(2, [day, day], [0.5, 0.5])
rep = RepresentativePeriods(2, 8760.0, [25, 25]/50, [opscen_summer, opscen_winter]);
ts = TwoLevel(n_sp, dur_sp, rep, op_per_strat=8760.0);

The time structure is in this case of type TwoLevel{Int64, Int64, RepresentativePeriods{Float64, Int64, OperationalScenarios{Int64, SimpleTimes{Int64}}}}. If we change it a bit to

rep = RepresentativePeriods(2, 8760.0, [25, 25]/50, [opscen_summer, day]);
ts = TwoLevel(n_sp, dur_sp, rep, op_per_strat=8760.0);

we lost the knowledge as it is not of type TwoLevel{Int64, Int64, RepresentativePeriods{Float64, Int64, TimeStructure{Int64}}}. It can however be beneficial to have an understanding of whether a time structure has representative periods and operational scenarios for only declaring variables when these are required. A current (crude) implementation in EnergyModelsBase is rather limited and does not allow for a TwoLevelTree.

Potential solutions

We can create an iterative procedure which identifies whether operational scenarios are required:

function has_opscenarios(ts::TwoLevelTree, tmp::Bool = false)
    for strat_node ∈ ts.nodes
        tmp = has_opscenarios(strat_node.operational, tmp)
        tmp && break
    end
    return tmp
end
function has_opscenarios(ts::TwoLevel, tmp::Bool = false)
    for sub_ts ∈ ts.operational
        tmp = has_opscenarios(sub_ts, tmp)
        tmp && break
    end
    return tmp
end
function has_opscenarios(ts::RepresentativePeriods, tmp::Bool = false)
    for sub_ts ∈ ts.rep_periods
        tmp = has_opscenarios(sub_ts, tmp)
        tmp && break
    end
    return tmp
end
has_opscenarios(ts::OperationalScenarios, tmp::Bool = false) = true
has_opscenarios(ts::SimpleTimes, tmp::Bool = false) = false
has_opscenarios(ts::CalendarTimes, tmp::Bool = false) = false

A similar procedure could also be declared for RepresentativePeriods. There may still be potential problems in a model if a mixed time structure is created and these implications are not considered, but I think that it would be a good support for external users when creating models.

Note

I would hope that we get this through before 1.0. It should however be included at latest 1.0