PortfolioOptimisers.jl

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Base search cross validation ​

PortfolioOptimisers.SearchCV Type
julia
const SearchCV = Union{<:KFold, <:KFoldResult, <:WalkForwardEstimator, <:WalkForwardResult}

Cross-validations compatible with search-based hyperparameter tuning.

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PortfolioOptimisers.AbstractSearchCrossValidationEstimator Type
julia
abstract type AbstractSearchCrossValidationEstimator <: AbstractEstimator

Abstract supertype for all search-based cross-validation estimators in PortfolioOptimisers.jl.

Subtypes implement hyperparameter search strategies (e.g. grid search, randomised search) that use cross-validation to select the best estimator configuration.

Related

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PortfolioOptimisers.CrossValidationSearchScorer Type
julia
abstract type CrossValidationSearchScorer <: AbstractEstimator

Defines the interface for scoring strategies used in search cross-validation. Implementations select the optimal parameter set based on cross-validation scores.

Interfaces

  • (::CrossValidationSearchScorer)(scores::AbstractMatrix): Returns the index of the optimal parameter set.

Arguments

  • scores: Matrix of scores, where each column corresponds to a parameter set and each row to a cross-validation split.

Returns

  • Int: Index of the optimal parameter set.

Examples

julia
julia> struct MyScore <: PortfolioOptimisers.CrossValidationSearchScorer end

julia> (s::MyScore)(X::Matrix{Float64}) = argmin(dropdims(mean(X; dims = 1); dims = 1))

julia> scores = [0.5 0.6; 0.7 0.8];

julia> scorer = MyScore()
MyScore()

julia> scorer(scores)
1

Related Types

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PortfolioOptimisers.CrossValSearchScorer Type
julia
const CrossValSearchScorer = Union{<:CrossValidationSearchScorer, <:Function}

Union type for search cross-validation scoring strategies. Accepts either a subtype of CrossValidationSearchScorer or a plain function that accepts a matrix and returns an integer.

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PortfolioOptimisers.HighestMeanScore Type
julia
struct HighestMeanScore <: CrossValidationSearchScorer

A CrossValidationSearchScorer that selects the parameter set with the highest mean score across cross-validation splits.

When called with a score matrix (rows = CV splits, columns = parameter sets), it returns the column index with the largest mean score.

Examples

julia
julia> scorer = PortfolioOptimisers.HighestMeanScore();

julia> scores = [0.5 0.8; 0.6 0.7];

julia> scorer(scores)
2

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PortfolioOptimisers.AbstractSearchCrossValidationResult Type
julia
abstract type AbstractSearchCrossValidationResult <: AbstractResult

Abstract result type for search-based cross-validation routines. Serves as the parent for all result types produced by search cross-validation algorithms, encapsulating optimal estimator, score matrices, parameter grid, and selected index.

Interfaces

  • Subtypes must store the optimal estimator, test and train scores, parameter grid, and selected index.
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PortfolioOptimisers.AbstractSearchCrossValidationAlgorithm Type
julia
abstract type AbstractSearchCrossValidationAlgorithm <: AbstractAlgorithm

Abstract supertype for all search-based cross-validation algorithm types.

Subtypes define the strategy used to select the best hyperparameter combination from the search results (e.g. selecting by highest mean score).

Related

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PortfolioOptimisers.SearchCrossValidationResult Type
julia
struct SearchCrossValidationResult{__T_opt, __T_test_scores, __T_train_scores, __T_lens_grid, __T_val_grid, __T_idx} <: AbstractSearchCrossValidationResult

Result type for search-based cross-validation routines. Stores the optimal estimator, score matrices, parameter grid, and selected index for hyperparameter search.

Fields

  • opt: Optimal estimator instance after search.

  • test_scores: Matrix of test scores for each parameter set and CV split.

  • train_scores: Matrix of training scores for each parameter set and CV split (or nothing if not recorded).

  • lens_grid: Vector of lens objects for parameter access.

  • val_grid: Vector of parameter values for each configuration.

  • idx: Index of the selected optimal parameter set.

Examples

Related

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PortfolioOptimisers.fit_and_score Function
julia
fit_and_score(opt::NonFiniteAllocationOptimisationEstimator,
              scv::AbstractSearchCrossValidationEstimator,
              rd::ReturnsResult,
              train_idx::VecInt,
              test_idx::VecInt)

Fits a portfolio optimisation estimator on training data, scores it on test and train splits, and returns the scores for search-based cross-validation routines.

Arguments

  • opt: Portfolio optimisation estimator to fit.

  • scv: Search cross-validation estimator specifying risk measure and options.

  • rd: Returns result containing asset returns data.

  • train_idx: Indices for training split.

  • test_idx: Indices for test split.

Returns

  • test_score::Number: Test score.

  • train_score::Option{<:Number}: Train score.

Details

  • Fits the estimator on training data.

  • Predicts on test data using the fitted estimator.

  • Computes risk scores for test and train splits.

  • Applies sign convention based on risk measure direction.

  • Returns scores for use in search cross-validation.

Related

Examples

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PortfolioOptimisers.parse_lens Function
julia
parse_lens(key::AbstractString)

Parse a hyperparameter key string into an Accessors.jl lens.

Converts a dotted string path (e.g., "opt.pe.ce") into a composable lens for getting and setting nested fields of an estimator object.

Arguments

  • key: Dotted field path string.

Returns

  • Composed Accessors.jl lens.

Related

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PortfolioOptimisers._expr_to_lens Function
julia
_expr_to_lens(ex::Symbol)

Convert a bare symbol into a PropertyLens for field access.

Base case for the lens-building recursion: a bare symbol maps directly to an Accessors.PropertyLens.

Arguments

  • ex::Symbol: A field name symbol.

Returns

  • Accessors.PropertyLens for the symbol.

Related

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PortfolioOptimisers._eval_index Function
julia
_eval_index(x)

Evaluate a literal index node in the AST without runtime eval.

Converts integer, symbol, or vector expression AST nodes to concrete index values for use in Accessors.IndexLens.

Arguments

  • x::Integer: An integer index.

  • x::Symbol: A symbolic index.

  • ex::Expr: A vector expression (:vect head).

Returns

  • The evaluated index value.

Related

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PortfolioOptimisers._expr_to_lens_chain Function
julia
_expr_to_lens_chain(ex)

Convert a Julia expression to a chain of lens accessors.

Internal helper for parsing hyperparameter key strings into composable Accessors.jl lenses.

Arguments

  • ex: Julia expression representing a field access chain.

Returns

  • Composed lens.

Related

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