From 77d070a26a23318e8ff1fd89bfc735bf109668b5 Mon Sep 17 00:00:00 2001
From: Bru <a.bruno@aluno.ufabc.edu.br>
Date: Fri, 5 Jan 2024 07:23:02 -0300
Subject: [PATCH] Creating K-Subjects out evaluations (#470)

* Creating K-Subjects out

* Fixing the tqdm

* [pre-commit.ci] auto fixes from pre-commit.com hooks

* Removing code not use

* Updating whats_new.rst

* Fixing whats new

* fixing again

---------

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
---
 docs/source/whats_new.rst        |  1 +
 moabb/evaluations/base.py        |  2 ++
 moabb/evaluations/evaluations.py | 11 ++++++++++-
 3 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/docs/source/whats_new.rst b/docs/source/whats_new.rst
index b361f18c5..6a322032b 100644
--- a/docs/source/whats_new.rst
+++ b/docs/source/whats_new.rst
@@ -20,6 +20,7 @@ Enhancements
 
 - Adding cache option to the evaluation (:gh:`517` by `Bruno Aristimunha`_)
 - Option to interpolate channel in paradigms' `match_all` method (:gh:`480` by `Gregoire Cattan`_)
+- Adding leave k-Subjects out evaluations (:gh:`470` by `Bruno Aristimunha`_)
 
 Bugs
 ~~~~
diff --git a/moabb/evaluations/base.py b/moabb/evaluations/base.py
index b9aafc5f4..b99eefaaa 100644
--- a/moabb/evaluations/base.py
+++ b/moabb/evaluations/base.py
@@ -66,6 +66,7 @@ def __init__(
         return_epochs=False,
         return_raws=False,
         mne_labels=False,
+        n_splits=None,
         save_model=False,
         cache_config=None,
     ):
@@ -77,6 +78,7 @@ def __init__(
         self.return_epochs = return_epochs
         self.return_raws = return_raws
         self.mne_labels = mne_labels
+        self.n_splits = n_splits
         self.save_model = save_model
         self.cache_config = cache_config
         # check paradigm
diff --git a/moabb/evaluations/evaluations.py b/moabb/evaluations/evaluations.py
index b3fce6b64..fc11fb7b0 100644
--- a/moabb/evaluations/evaluations.py
+++ b/moabb/evaluations/evaluations.py
@@ -8,6 +8,7 @@
 from sklearn.base import clone
 from sklearn.metrics import get_scorer
 from sklearn.model_selection import (
+    GroupKFold,
     LeaveOneGroupOut,
     StratifiedKFold,
     StratifiedShuffleSplit,
@@ -632,6 +633,9 @@ class CrossSubjectEvaluation(BaseEvaluation):
         use MNE raw to train pipelines.
     mne_labels: bool, default=False
         if returning MNE epoch, use original dataset label if True
+    n_splits: int, default=None
+        Number of splits for cross-validation. If None, the number of splits
+        is equal to the number of subjects.
     """
 
     # flake8: noqa: C901
@@ -675,7 +679,12 @@ def evaluate(
         scorer = get_scorer(self.paradigm.scoring)
 
         # perform leave one subject out CV
-        cv = LeaveOneGroupOut()
+        if self.n_splits is None:
+            cv = LeaveOneGroupOut()
+        else:
+            cv = GroupKFold(n_splits=self.n_splits)
+            n_subjects = self.n_splits
+
         inner_cv = StratifiedKFold(3, shuffle=True, random_state=self.random_state)
 
         # Implement Grid Search