skfolio.model_selection
.CombinatorialPurgedCV#
- class skfolio.model_selection.CombinatorialPurgedCV(n_folds=10, n_test_folds=8, purged_size=0, embargo_size=0)[source]#
Combinatorial Purged Cross-Validation.
Provides train/test indices to split time series data samples based on Combinatorial Purged Cross-Validation [1].
Compared to
KFold
, which splits the data intok
folds with1
fold for the test set andk - 1
folds for the training set,CombinatorialPurgedCV
usesk - p
folds for the training set withp > 1
being the number of test folds.KFold
can recombine one single testing path whileCombinatorialPurgedCV
can recombine multiple testing paths from the combinations of the train/test sets.To avoid data leakage, purging and embargoing can be performed.
Purging consist of removing from the training set all observations whose labels overlapped in time with those labels included in the testing set.
Embargoing consist of removing from the training set all observations that immediately follow an observation in the testing set, since financial features often incorporate series that exhibit serial correlation (like ARMA processes).
- Parameters:
- n_foldsint, default=10
Number of folds. Must be at least 3.
- n_test_foldsint, default=8
Number of test folds. Must be at least 2. For only one test fold, use
sklearn.model_validation.KFold
.- purged_sizeint, default=0
Number of observations to exclude from the start of each train set that are after a test set and the number of observations to exclude from the end of each training set that are before a test set.
- embargo_sizeint, default=0
Number of observations to exclude from the start of each training set that are after a test set.
- Attributes:
- index_train_test_ndarray of shape (n_observations, n_splits)
References
[1]“Advances in Financial Machine Learning”, Marcos López de Prado (2018)
Examples
>>> import numpy as np >>> from skfolio.model_selection import CombinatorialPurgedCV >>> X = np.random.randn(12, 2) >>> cv = CombinatorialPurgedCV(n_folds=3, n_test_folds=2) >>> for i, (train_index, tests) in enumerate(cv.split(X)): ... print(f"Split {i}:") ... print(f" Train: index={train_index}") ... for j, test_index in enumerate(tests): ... print(f" Test {j}: index={test_index}") Split 0: Train: index=[ 8 9 10 11] Test 0: index=[0 1 2 3] Test 1: index=[4 5 6 7] Split 1: Train: index=[4 5 6 7] Test 0: index=[0 1 2 3] Test 1: index=[ 8 9 10 11] Split 2: Train: index=[0 1 2 3] Test 0: index=[4 5 6 7] Test 1: index=[ 8 9 10 11] >>> cv = CombinatorialPurgedCV(n_folds=3, n_test_folds=2, purged_size=1) >>> for i, (train_index, tests) in enumerate(cv.split(X)): ... print(f"Split {i}:") ... print(f" Train: index={train_index}") ... for j, test_index in enumerate(tests): ... print(f" Test {j}: index={test_index}") Split 0: Train: index=[ 9 10 11] Test 0: index=[0 1 2 3] Test 1: index=[4 5 6 7] Split 1: Train: index=[5 6] Test 0: index=[0 1 2 3] Test 1: index=[ 8 9 10 11] Split 2: Train: index=[0 1 2] Test 0: index=[4 5 6 7] Test 1: index=[ 8 9 10 11] >>> cv = CombinatorialPurgedCV(n_folds=3, n_test_folds=2, embargo_size=1) >>> for i, (train_index, tests) in enumerate(cv.split(X)): ... print(f"Split {i}:") ... print(f" Train: index={train_index}") ... for j, test_index in enumerate(tests): ... print(f" Test {j}: index={test_index}") Split 0: Train: index=[ 9 10 11] Test 0: index=[0 1 2 3] Test 1: index=[4 5 6 7] Split 1: Train: index=[5 6 7] Test 0: index=[0 1 2 3] Test 1: index=[ 8 9 10 11] Split 2: Train: index=[0 1 2 3] Test 0: index=[4 5 6 7] Test 1: index=[ 8 9 10 11]
Methods
Return the path id of each test sets in each split
Plot the train/test fold locations
Plot the training and test indices for each combinations by assigning
0
to training,1
to test and-1
to both purge and embargo indices.split
(X[, y, groups])Generate indices to split data into training and test set.
summary
- property binary_train_test_sets#
Identify training and test folds for each combinations by assigning
0
to training folds and1
to test folds
- property n_splits#
Number of splits
- property n_test_paths#
Number of test paths that can be reconstructed from the train/test combinations
- plot_train_test_index(X)[source]#
Plot the training and test indices for each combinations by assigning
0
to training,1
to test and-1
to both purge and embargo indices.
- property recombined_paths#
Recombine each test path by returning the test set location in each split.
- split(X, y=None, groups=None)[source]#
Generate indices to split data into training and test set.
- Parameters:
- Xarray-like of shape (n_samples, n_features)
Training data, where
n_samples
is the number of samples andn_features
is the number of features.- yarray-like of shape (n_samples,), optional
The (multi-)target variable
- groupsarray-like of shape (n_samples,), optional
Group labels for the samples used while splitting the dataset into train/test set.
- Yields:
- trainndarray
The training set indices for that split.
- testndarray
The testing set indices for that split.
- property test_set_index#
Location of each test set