Modules

Module perform a single transformation in the modelspec functional cascade. They should contain only string and numerical values (not functions themselves) so that they can be converted to JSON format for saving.

Each module is described by a dictionary with several key/value pairs. Some are required:

Required

• fn: pathspec to function that performs the transformation (e.g., nems.modules.fir.basic) This function should accept a Recording object and return a dictionary of signals, typically only signals that were modified or created by fn. These signals will be merged into the recording and passed to the next module in the modelspec cascade.

• fn_kwargs: dictionary of fixed args passed to fn. Can be empty, but typically contains:

  • i: name of input signal

  • o: name of output signal

  • s name of state signal

• phi: dictionary of free parameters, concatenated with fn_kwargs and passed to fn for evaluation. These parameters are updated during fitting.

Optional

• plot_fns

• plot_fn_idx

• priors

The only mandatory field in each module dict is fn. All other fields are optional. Presently, we have reserved the following fields for specific uses:

Field	Type	Description
id	str	Name of the module keyword that created this dict.
fn	str	The pure transformation function.
fn_kwargs	dict	Non-fittable arguments that are passed to fn.
meta	dict	A dictionary of metadata, descriptions, benchmarks, etc
phi	dict	Like fn, but fittable. The “parameters” of the module.
prior	dict	Defines a prior distribution from which bounds or
		samples may be drawn by the fitter during optimization.

You may place whatever information at all you like in meta without consulting anyone – “description”, “date”, “notes”, or information on fitters and data files are all good types of things to put in the meta dict. However, in the interests of forcing helpful design discussions, if you wish to establish a convention for another top-level field for modules, please bring it up in the NEMS Gitter channel

Making your own module

TODO