This notebook tutorial explains the basics of spaces, by taking a closer look at spaces defined in the simplelife model as an example.
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A new simplelife model is created and returned by build
function in lifelib project. Import simplelife in your working folder.
Nextime you create the same model, you can give load_saved
parameter True
, to save time to load input data.
import modelx as mx
model = mx.read_model("model")
The previously created model is renamed automatically to avoid name conflict. To get all existing models, get_models
modelx API function can be used. get_models
returns a dict of all the existing models associated with their names.
import modelx as mx
mx.get_models()
In the model, there are child spaces and other objects referenced in the model. spaces
property holds pairs of child space names and objects as a dict-like view.
model.spaces
To just get all the names of the spaces, use the idiomatic expression below. To get all the space objects, values
method can be used instead of keys
.
list(model.spaces.keys())
To get a specific space, simply type its name as model's attribute, or pass the name as a key to spaces property. For example, to get Projection
space:
model.Projection
or
model.spaces['Projection']
A space can in turn contain other spaces, forming a space tree. To access child spaces of a space, the spaces
property and attribute access by name as we used on models can be used.
model.Projection.spaces
model.Projection.Assumptions
model.Projection.spaces['Assumptions']
Below is the list of the names of the spaces in the simplelife model.
list(model.spaces.keys())
Below is a brief explanation of each space directly under the model.
Input
: Parent space containing spaces and cells hoding data read from the input file.LifeTable
: Space containing cells related to commutation functions and actuarial notations.Policy
: Parametric space whose dynamic child spaces hold attribute data of each policy read from the input file.Assumption
: Parametric space whose dynamic child spaces hold assumptions for each policy.Economic
: Parametric space whose dynamic child spaces hold economic assumptions for each scenario.BaseProj
: Base space of Projection
space, which contains cells to carry out projections.PV
: Mixin space to Projection
space, which contains cells to calculate present values of cashflows.Projection
: Parametric space, whose dynamic child spaces carry out projection for each policy.BaseProj
and PV
are base spaces of Projection
, and cells defined in those cells are copied into Projection
space.
model.Projection.bases
Among the spaces listed above, parametric spaces along with their parameters are listed below.
LifeTable[Sex, IntRate, TableID]
Policy[PolicyID]
Assumption[PolicyID]
Economic[ScenID]
Projection[PolicyID, ScenID=1]
To check parameters of a parametric space, call its parameters
property.
model.LifeTable.parameters
A space becomes parametric when it has the formula
property. By calling the formula
property, the source code of the function the formula is created from is printed.
The paramters of a parametric space, and their default values if any, are taken from the signature of its associated function.
model.LifeTable.formula
Parameter spaces serve as factories to create their child spaces dynamically.
When a parametric space is called with specific arguments being passed to the parameters, a dynamic child space associated with the arguments is created if it's not yet created, and returned. This can be achieved either by the call operation ()
or by subscription []
on the parametric space. If a parameter has its default value, and the arguments to the parameter is omitted, the default value is passed.
model.Projection[1]
Space formulas have 2 roles relating to dynamic element spaces.
When the user tries to access the element space of a space, such as model.Projection[1]
, for the first time, the formula of the space is called in order to pass a dictionary of pairs of parameters and arguments used for constructing and initializing the element space.
The parameters include:
bases
: a list of base spaces of the element space. If not specified, the space itself becomes the direct base space of the element space.refs
: a dictionary of references to be defined in the element space.Both of the parameters are optional. As we have seen in the above, space formulas are created from function definitions.
model.Projection.formula
The formula code is executed in the namespace associated with the space. Note that the global scope of the function underlying the formula has nothing to do with the formula's scope. So, names such as Policy
, Assumption
, Economic
that appear in the formula above are defined in the namespace of model.Projection
.
The names defined in the namespace consists of child cells, child spaces and references in the space,
i.e. the namespace is the union of cells
, spaces
, refs
properties.
dir
function on a space lists all the names defined in the namespace associated with the space.
dir(model.Projection)