parameter
Stable type · Document types
Tier: stable · Kind: type · Topic: Document types
| Julia | TypeScript | Python | Rust | Go |
|---|---|---|---|---|
Parameter | not exported | Parameter | not exported | Parameter |
Julia
struct Parameter
Parameter(name::String; ...)
Parameter(name::String, default::Union{Nothing, Real}; description, units, default_units, shape, distribution, update)
Parameter
A reaction system’s parameter (reaction_systems.*.parameters.*) — the
reaction-side twin of a ModelVariable
of ParameterVariable type,
and it carries the SAME value model (esm-spec §5.4, §6.3): a default, a
distribution, a shape, and an update rule set.
esm-schema.json’s Parameter declares NO required properties, so default
is optional: a parameter valued by a distribution — or one whose whole value
is supplied by an update binding to a data source — is a legal document with
no default at all. It is Union{Float64,Nothing} for exactly that reason.
shape / distribution / update are here for the same reason they are on
ModelVariable: the schema defines them and a field this struct does not hold
is a field load silently drops. update is the load-bearing one — an
update block is the only channel binding a parameter to a data source
(§5.4), so dropping it does not just lose annotation, it turns a data-driven
parameter into a constant.
TypeScript
TypeScript does not export this type.
Python
class Parameter
Parameter(name: str, value: float | Expr, units: str | None = None, default_units: str | None = None, description: str | None = None, uncertainty: float | None = None, shape: list[str] | None = None, distribution: Distribution | None = None, update: ParameterUpdate | list[ParameterUpdate] | None = None)
A parameter for reaction systems.
Carries the same value machinery as a model parameter (schema
$defs/Parameter): a fixed default (value here) OR a distribution,
plus an optional update saying when it refreshes and what from, and a
shape naming the index sets an arrayed parameter is declared over.
Rust
Rust does not export this type.
Go
type Parameter struct {
Units *string `json:"units,omitempty"`
Default any `json:"default,omitempty"`
// DefaultUnits declares the units the scalar `default` is expressed in when
// they differ from `units`. `omitempty`: optional, usually absent.
DefaultUnits *string `json:"default_units,omitempty"`
Description *string `json:"description,omitempty"`
// Shape lists index-set names for an arrayed parameter, exactly as
// ModelVariable.Shape does — and for the same reason it is a POINTER to a
// slice rather than a plain one. `omitempty` on a `*[]string` omits only the
// NIL pointer (the key was absent); a pointer to an EMPTY slice still emits
// `"shape": []`. That distinction is load-bearing here: esm-schema.json
// REQUIRES `shape` on a parameter whose `update` kind is `schedule`, `data`,
// or `remesh` (esm-spec §5.4), and every such parameter in the corpus is a
// scalar authored as `"shape": []`. A plain `[]string` would collapse the
// authored empty array into an omitted key and re-emit a schema-INVALID
// document. Read it through Dims().
Shape *[]string `json:"shape,omitempty"`
// Distribution draws the parameter's value from a closed-set distribution
// instead of fixing it at `default` (mutually exclusive with it).
Distribution *Distribution `json:"distribution,omitempty"`
// Update is the ParameterUpdateSpec union — one ParameterUpdate object or an
// ordered array of two or more — held as `any` for the same reason
// ModelVariable.Update is. Read it through UpdateRules().
Update any `json:"update,omitempty"`
}
func (p *Parameter) ClearDims()
func (p Parameter) Dims() []string
func (p Parameter) HasUpdate() bool
func (p *Parameter) SetDims(dims []string)
func (p *Parameter) SetUpdate(rules []ParameterUpdate)
func (p *Parameter) UnmarshalJSON(data []byte) error
func (p Parameter) UpdateRules() []ParameterUpdate
Parameter represents a reaction-system parameter — rate constant, temperature, photolysis rate.
It carries the SAME value machinery as a model parameter (esm-schema.json $defs/Parameter, whose own description says so): a fixed default or a distribution, an optional shape, and an optional update saying when it refreshes. Modelling only units/default/description made the type lossy in a way that changed MEANING rather than presentation: an update block is the only channel binding a parameter to a data_sources entry (esm-spec §5.4), so dropping it silently converted a data-driven parameter into a constant held at its default.
Methods
func (p *Parameter) ClearDims()
ClearDims removes the shape key entirely.
func (p Parameter) Dims() []string
Dims returns the parameter’s declared index-set axes, treating an absent shape and an authored empty one alike (both are scalar). Mirrors ModelVariable.Dims.
func (p Parameter) HasUpdate() bool
HasUpdate reports whether the parameter carries any update rule.
func (p *Parameter) SetDims(dims []string)
SetDims sets the parameter’s shape to the given axes, materializing the pointer. Passing a nil slice records an authored "shape": []; call ClearDims to drop the key entirely. Mirrors ModelVariable.SetDims.
func (p *Parameter) SetUpdate(rules []ParameterUpdate)
SetUpdate stores the given rules in the canonical spelling of the union: a lone rule as the OBJECT form (a one-element array is invalid per esm-spec §5.4) and two or more as the array form. No rules clears the field.
func (p *Parameter) UnmarshalJSON(data []byte) error
Custom JSON unmarshaling for Parameter. Decodes default through UnmarshalExpression so an integer-valued default keeps its int wire shape (RFC §5.4.1); a plain decode would coerce it to float64 and re-emit “1.0”. shape and update are decoded exactly as ModelVariable decodes them — the pointer-to-slice keeps an authored "shape": [] distinguishable from an absent key, and unmarshalParameterUpdateSpec normalizes the §5.4 union.
func (p Parameter) UpdateRules() []ParameterUpdate
UpdateRules returns the parameter’s update rules in declaration order, flattening both spellings of the ParameterUpdateSpec union (esm-spec §5.4). Mirrors ModelVariable.UpdateRules.