refactor: remove get_u0_p, modernize get_u0 and add get_p

Author: AayushSabharwal

src/systems/problem_utils.jl

@@ -1700,97 +1700,45 @@ function maybe_codegen_scimlproblem(::Type{Val{false}}, T, args::NamedTuple; kwa
     remake(T(args...; kwargs...))
 end
 
-##############
-# Legacy functions for backward compatibility
-##############
-
 """
-    u0, p, defs = get_u0_p(sys, u0map, parammap; use_union=true, tofloat=true)
+    $(TYPEDSIGNATURES)
 
-Take dictionaries with initial conditions and parameters and convert them to numeric arrays `u0` and `p`. Also return the merged dictionary `defs` containing the entire operating point.
+Return the `u0` vector for the given system `sys` and variable-value mapping `varmap`. All
+keyword arguments are forwarded to [`varmap_to_vars`](@ref).
 """
-function get_u0_p(sys,
-        u0map,
-        parammap = nothing;
-        t0 = nothing,
-        tofloat = true,
-        use_union = true,
-        symbolic_u0 = false)
+function get_u0(sys::AbstractSystem, varmap; kwargs...)
     dvs = unknowns(sys)
     ps = parameters(sys; initial_parameters = true)
+    op = to_varmap(varmap, dvs)
+    add_observed!(sys, op)
+    add_parameter_dependencies!(sys, op)
+    missing_dvs, _ = build_operating_point!(sys, op, Dict(), defaults(sys), dvs, ps)
 
-    defs = defaults(sys)
-    if t0 !== nothing
-        defs[get_iv(sys)] = t0
-    end
-    if parammap !== nothing
-        defs = mergedefaults(defs, parammap, ps)
-    end
-    if u0map isa Vector && eltype(u0map) <: Pair
-        u0map = Dict(u0map)
-    end
-    if u0map isa Dict
-        allobs = Set(observables(sys))
-        if any(in(allobs), keys(u0map))
-            u0s_in_obs = filter(in(allobs), keys(u0map))
-            @warn "Observed variables cannot be assigned initial values. Initial values for $u0s_in_obs will be ignored."
-        end
-    end
-    obs = filter!(x -> !(x[1] isa Number), map(x -> x.rhs => x.lhs, observed(sys)))
-    observedmap = isempty(obs) ? Dict() : todict(obs)
-    defs = mergedefaults(defs, observedmap, u0map, dvs)
-    for (k, v) in defs
-        if Symbolics.isarraysymbolic(k)
-            ks = scalarize(k)
-            length(ks) == length(v) || error("$k has default value $v with unmatched size")
-            for (kk, vv) in zip(ks, v)
-                if !haskey(defs, kk)
-                    defs[kk] = vv
-                end
-            end
-        end
-    end
+    isempty(missing_dvs) || throw(MissingVariablesError(collect(missing_dvs)))
 
-    if symbolic_u0
-        u0 = varmap_to_vars(u0map, dvs; defaults = defs, tofloat = false, use_union = false)
-    else
-        u0 = varmap_to_vars(u0map, dvs; defaults = defs, tofloat, use_union)
-    end
-    p = varmap_to_vars(parammap, ps; defaults = defs, tofloat, use_union)
-    p = p === nothing ? SciMLBase.NullParameters() : p
-    t0 !== nothing && delete!(defs, get_iv(sys))
-    u0, p, defs
+    return varmap_to_vars(op, dvs; kwargs...)
 end
 
-function get_u0(
-        sys, u0map, parammap = nothing; symbolic_u0 = false,
-        toterm = default_toterm, t0 = nothing, use_union = true)
+"""
+    $(TYPEDSIGNATURES)
+
+Return the `u0` vector for the given system `sys` and variable-value mapping `varmap`. All
+keyword arguments are forwarded to [`MTKParameters`](@ref) for split systems and
+[`varmap_to_vars`](@ref) for non-split systems.
+"""
+function get_p(sys::AbstractSystem, varmap; kwargs...)
     dvs = unknowns(sys)
-    ps = parameters(sys)
-    defs = defaults(sys)
-    if t0 !== nothing
-        defs[get_iv(sys)] = t0
-    end
-    if parammap !== nothing
-        defs = mergedefaults(defs, parammap, ps)
-    end
-
-    # Convert observed equations "lhs ~ rhs" into defaults.
-    # Use the order "lhs => rhs" by default, but flip it to "rhs => lhs"
-    # if "lhs" is known by other means (parameter, another default, ...)
-    # TODO: Is there a better way to determine which equations to flip?
-    obs = map(x -> x.lhs => x.rhs, observed(sys))
-    obs = map(x -> x[1] in keys(defs) ? reverse(x) : x, obs)
-    obs = filter!(x -> !(x[1] isa Number), obs) # exclude e.g. "0 => x^2 + y^2 - 25"
-    obsmap = isempty(obs) ? Dict() : todict(obs)
-
-    defs = mergedefaults(defs, obsmap, u0map, dvs)
-    if symbolic_u0
-        u0 = varmap_to_vars(
-            u0map, dvs; defaults = defs, tofloat = false, use_union = false, toterm)
+    ps = parameters(sys; initial_parameters = true)
+    op = to_varmap(varmap, dvs)
+    add_observed!(sys, op)
+    add_parameter_dependencies!(sys, op)
+    _, missing_ps = build_operating_point!(sys, op, Dict(), defaults(sys), dvs, ps)
+
+    isempty(missing_ps) || throw(MissingParametersError(collect(missing_ps)))
+
+    if is_split(sys)
+        MTKParameters(sys, op; kwargs...)
     else
-        u0 = varmap_to_vars(u0map, dvs; defaults = defs, tofloat = true, use_union, toterm)
+        varmap_to_vars(op, ps; kwargs...)
     end
-    t0 !== nothing && delete!(defs, get_iv(sys))
-    return u0, defs
 end