params

Docs: GoDoc

See Wiki Params page for detailed docs.

Package params provides general-purpose parameter management functionality for organizing multiple sets of parameters efficiently, and basic IO for saving / loading from JSON files and generating Go code to embed into applications, and a basic GUI for viewing and editing.

IMPORTANT: as of July, 2023, params has been deprecated in favor of netparams which is focused only on Network params, for which the styling and structure of this params system makes the most sense. Use econfig for setting params on standard struct objects such as Config structs.

The main overall unit that is generally operated upon at run-time is the params.Set, which is a collection of params.Sheet's (akin to CSS style sheets) that constitute a coherent set of parameters. Here's the structure:

Sets {
    Set: "Base" {
        Sheets {
            "Network": {
                Sel: "Layer" {
                    Params: {
                        "Layer.Inhib.Layer.Gi": "1.1",
                        ...
                    }
                },
                Sel: ".Back" {
                    Params: {
                        "Path.PathScale.Rel": "0.2",
                        ...
                    }
                }
            },
            "Sim": {
                ...
            }
        }
    },
    Set: "Option1" {
        ...
    }
}        

A good strategy is to have a "Base" Set that has all the best parameters so far, and then other sets can modify specific params relative to that one. Order of application is critical, as subsequent params applications overwrite earlier ones, and the typical order is:

• Defaults() method called that establishes the hard-coded default parameters.
• Then apply "Base" params.Set for any changes relative to those.
• Then optionally apply one or more additional params.Set's with current experimental parameters.

Critically, all of this is entirely up to the particular model program(s) to determine and control -- this package just provides the basic data structures for holding all of the parameters, and the IO / and Apply infrastructure.

Within a params.Set, multiple different params.Sheet's can be organized, with each CSS-style sheet achieving a relatively complete parameter styling of a given element of the overal model, e.g., "Network", "Sim", "Env". Or Network could be further broken down into "Learn" vs. "Act" etc, or according to different brain areas ("Hippo", "PFC", "BG", etc). Again, this is entirely at the discretion of the modeler and must be performed under explict program control, especially because order is so critical.

Each params.Sheet consists of a collection of params.Sel elements which actually finally contain the parameters. The Sel field specifies a CSS-style selector determining over what scope the parameters should be applied:

• Type (no prefix) = name of a type -- anything having this type name will get these params.

• .Class = anything with a given class label (each object can have multiple Class labels and thus receive multiple parameter settings, but again, order matters!)

• #Name = a specific named object.

The order of application within a given Sheet is also critical -- typically put the most general Type params first, then .Class, then the most specific #Name cases, to achieve within a given Sheet the same logic of establishing Base params for all types and then more specific overrides for special cases (e.g., an overall learning rate that appplies across all pathways, but maybe a faster or slower one for a .Class or specific #Name'd pathway).

There is a params.Styler interface with methods that any Go type can implement to provide these different labels. The emer.Network, .Layer, and .Path interfaces each implement this interface.

Otherwise, the Apply method will just directly apply params to a given struct type if it does not implement the Styler interface.

Parameter values are stored as strings, which can represent any value.

Finally, there are methods to show where params.Set's set the same parameter differently, and to compare with the default settings on a given object type using go struct field tags of the form def:"val1[,val2...]".

Providing direct access to specific params

The best way to provide the user direct access to specific parameter values through the Params mechanisms is to put the relevant params in the Sim object, where they will be editable fields, and then call SetFloat or SetString as appropriate with the path to the parameter in question, followed by a call to apply the params.

The current value can be obtained by the ParamVal methods.