From 96c68703c510a695751072bd6a35a5add50aaf1d Mon Sep 17 00:00:00 2001
From: Julien Jerphanion <git@jjerphan.xyz>
Date: Mon, 12 Dec 2022 10:53:30 +0100
Subject: [PATCH 01/12] FIX Make `cd_fast` use cnp.ndarray to support readonly
 buffers

Follow-up of #23147.
---
 sklearn/linear_model/_cd_fast.pyx | 23 +++++++++++++----------
 1 file changed, 13 insertions(+), 10 deletions(-)

diff --git a/sklearn/linear_model/_cd_fast.pyx b/sklearn/linear_model/_cd_fast.pyx
index 0c28d9929be63..72d2466593dab 100644
--- a/sklearn/linear_model/_cd_fast.pyx
+++ b/sklearn/linear_model/_cd_fast.pyx
@@ -92,11 +92,12 @@ cdef floating diff_abs_max(int n, floating* a, floating* b) nogil:
 
 
 def enet_coordinate_descent(
-    floating[::1] w,
+    # TODO: const-qualify fused typed memoryview when Cython 3 is used (#23147)
+    cnp.ndarray[floating, ndim=1, mode='c']  w,
     floating alpha,
     floating beta,
     floating[::1, :] X,
-    floating[::1] y,
+    cnp.ndarray[floating, ndim=1, mode='c'] y,
     unsigned int max_iter,
     floating tol,
     object rng,
@@ -274,15 +275,16 @@ def enet_coordinate_descent(
 
 
 def sparse_enet_coordinate_descent(
-    floating [::1] w,
+    # TODO: const-qualify fused typed memoryview when Cython 3 is used (#23147)
+    cnp.ndarray[floating, ndim=1, mode='c'] w,
     floating alpha,
     floating beta,
-    floating[::1] X_data, # TODO: Make const after release of Cython 3 (#23147)
+    cnp.ndarray[floating, ndim=1, mode='c'] X_data,
     const int[::1] X_indices,
     const int[::1] X_indptr,
-    floating[::1] y,
-    floating[::1] sample_weight,
-    floating[::1] X_mean,
+    cnp.ndarray[floating, ndim=1, mode='c'] y,
+    cnp.ndarray[floating, ndim=1, mode='c'] sample_weight,
+    cnp.ndarray[floating, ndim=1, mode='c'] X_mean,
     unsigned int max_iter,
     floating tol,
     object rng,
@@ -565,7 +567,8 @@ def sparse_enet_coordinate_descent(
 
 
 def enet_coordinate_descent_gram(
-    floating[::1] w,
+    # TODO: const-qualify fused typed memoryview when Cython 3 is used (#23147)
+    cnp.ndarray[floating, ndim=1, mode='c'] w,
     floating alpha,
     floating beta,
     cnp.ndarray[floating, ndim=2, mode='c'] Q,
@@ -736,10 +739,10 @@ def enet_coordinate_descent_gram(
 
 
 def enet_coordinate_descent_multi_task(
-    floating[::1, :] W,
+    # TODO: const-qualify fused typed memoryview when Cython 3 is used (#23147)
+    cnp.ndarray[floating, ndim=2, mode='fortran'] W,
     floating l1_reg,
     floating l2_reg,
-    # TODO: use const qualified fused-typed memoryview when Cython 3.0 is used.
     cnp.ndarray[floating, ndim=2, mode='fortran'] X,
     cnp.ndarray[floating, ndim=2, mode='fortran'] Y,
     unsigned int max_iter,

From 73fa2437b2867398c68750c41c8c9af378b20d66 Mon Sep 17 00:00:00 2001
From: Julien Jerphanion <git@jjerphan.xyz>
Date: Thu, 15 Dec 2022 14:19:23 +0100
Subject: [PATCH 02/12] MAINT Remove ReadonlyArrayWrapper

---
 sklearn/linear_model/_coordinate_descent.py | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/sklearn/linear_model/_coordinate_descent.py b/sklearn/linear_model/_coordinate_descent.py
index da4b82b19ede4..9ecfd1c2740a5 100644
--- a/sklearn/linear_model/_coordinate_descent.py
+++ b/sklearn/linear_model/_coordinate_descent.py
@@ -30,7 +30,6 @@
     check_is_fitted,
     column_or_1d,
 )
-from ..utils._readonly_array_wrapper import ReadonlyArrayWrapper
 from ..utils.fixes import delayed
 
 # mypy error: Module 'sklearn.linear_model' has no attribute '_cd_fast'
@@ -594,9 +593,7 @@ def enet_path(
                 w=coef_,
                 alpha=l1_reg,
                 beta=l2_reg,
-                X_data=ReadonlyArrayWrapper(
-                    X.data
-                ),  # TODO: Remove after release of Cython 3 (#23147)
+                X_data=X.data,
                 X_indices=X.indices,
                 X_indptr=X.indptr,
                 y=y,

From 8d1ce0e5d4795bf2b98c9690495ba80560123fd3 Mon Sep 17 00:00:00 2001
From: Julien Jerphanion <git@jjerphan.xyz>
Date: Fri, 16 Dec 2022 09:28:44 +0100
Subject: [PATCH 03/12] TST Add non-regression test for #25165
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

This test is built based on Loïc's reproducer:
https://github.com/scikit-learn/scikit-learn/issues/25165#issuecomment-1348588230

Co-authored-by: Loïc Esteve <loic.esteve@ymail.com>
---
 .../decomposition/tests/test_dict_learning.py | 24 +++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/sklearn/decomposition/tests/test_dict_learning.py b/sklearn/decomposition/tests/test_dict_learning.py
index 67d464b3f2884..5105062355fa2 100644
--- a/sklearn/decomposition/tests/test_dict_learning.py
+++ b/sklearn/decomposition/tests/test_dict_learning.py
@@ -1038,6 +1038,30 @@ def test_get_feature_names_out(estimator):
     )
 
 
+def test_cd_work_on_joblib_memmapped_data():
+    # Non-regression test for:
+    # https://github.com/scikit-learn/scikit-learn/issues/25165
+    # The Cython implementation of coordinate descent must work
+    # on readonly data.
+
+    rng = np.random.RandomState(0)
+    # This dataset is sufficient large to be memmapped by joblib
+    # and thus becomes readonly even if it originally isn't.
+    X_train = rng.randn(5000, 3072)
+
+    dict_learner = DictionaryLearning(
+        n_components=56,
+        random_state=0,
+        n_jobs=2,
+        fit_algorithm="cd",
+        verbose=True,
+        max_iter=50,
+    )
+
+    # This must run and complete without error.
+    dict_learner.fit(X_train)
+
+
 # TODO(1.4) remove
 def test_minibatch_dictionary_learning_warns_and_ignore_n_iter():
     """Check that we always raise a warning when `n_iter` is set even if it is

From c2234811785a06306fd732b8a4007d43dbc4d9c4 Mon Sep 17 00:00:00 2001
From: Julien Jerphanion <git@jjerphan.xyz>
Date: Fri, 16 Dec 2022 13:52:23 +0100
Subject: [PATCH 04/12] DEBUG Use ReadonlyArrayWrapper to support const
 qualification

Reverting to use cnp.ndarray does not solve the problem.
This is a tentative workaround using ReadonlyArrayWrapper.

This solves the problem, but there is now a segmentation fault.
---
 sklearn/linear_model/_cd_fast.pyx           | 12 ++++++------
 sklearn/linear_model/_coordinate_descent.py | 15 ++++++++++-----
 2 files changed, 16 insertions(+), 11 deletions(-)

diff --git a/sklearn/linear_model/_cd_fast.pyx b/sklearn/linear_model/_cd_fast.pyx
index 72d2466593dab..dc1c374d61f62 100644
--- a/sklearn/linear_model/_cd_fast.pyx
+++ b/sklearn/linear_model/_cd_fast.pyx
@@ -568,12 +568,12 @@ def sparse_enet_coordinate_descent(
 
 def enet_coordinate_descent_gram(
     # TODO: const-qualify fused typed memoryview when Cython 3 is used (#23147)
-    cnp.ndarray[floating, ndim=1, mode='c'] w,
+    floating[::1] w,
     floating alpha,
     floating beta,
-    cnp.ndarray[floating, ndim=2, mode='c'] Q,
-    cnp.ndarray[floating, ndim=1, mode='c'] q,
-    cnp.ndarray[floating, ndim=1] y,
+    floating[:, ::1] Q,
+    floating[::1] q,
+    floating[:] y,
     unsigned int max_iter,
     floating tol,
     object rng,
@@ -633,9 +633,9 @@ def enet_coordinate_descent_gram(
     cdef UINT32_t* rand_r_state = &rand_r_state_seed
 
     cdef floating y_norm2 = np.dot(y, y)
-    cdef floating* w_ptr = <floating*>&w[0]
+    cdef floating* w_ptr = &w[0]
     cdef floating* Q_ptr = &Q[0, 0]
-    cdef floating* q_ptr = <floating*>q.data
+    cdef floating* q_ptr = &q[0]
     cdef floating* H_ptr = &H[0]
     cdef floating* XtA_ptr = &XtA[0]
     tol = tol * y_norm2
diff --git a/sklearn/linear_model/_coordinate_descent.py b/sklearn/linear_model/_coordinate_descent.py
index 9ecfd1c2740a5..54bb9072c12f4 100644
--- a/sklearn/linear_model/_coordinate_descent.py
+++ b/sklearn/linear_model/_coordinate_descent.py
@@ -30,6 +30,7 @@
     check_is_fitted,
     column_or_1d,
 )
+from ..utils._readonly_array_wrapper import ReadonlyArrayWrapper
 from ..utils.fixes import delayed
 
 # mypy error: Module 'sklearn.linear_model' has no attribute '_cd_fast'
@@ -593,7 +594,9 @@ def enet_path(
                 w=coef_,
                 alpha=l1_reg,
                 beta=l2_reg,
-                X_data=X.data,
+                # TODO: remove ReadonlyArrayWrapper when const-qualify fused typed
+                # memoryviews are used (this necessiates Cython 3).
+                X_data=ReadonlyArrayWrapper(X.data),
                 X_indices=X.indices,
                 X_indptr=X.indptr,
                 y=y,
@@ -615,12 +618,14 @@ def enet_path(
             if check_input:
                 precompute = check_array(precompute, dtype=X.dtype.type, order="C")
             model = cd_fast.enet_coordinate_descent_gram(
-                coef_,
+                # TODO: remove ReadonlyArrayWrappers when const-qualify fused typed
+                # memoryviews are used (this necessiates Cython 3).
+                ReadonlyArrayWrapper(coef_),
                 l1_reg,
                 l2_reg,
-                precompute,
-                Xy,
-                y,
+                ReadonlyArrayWrapper(precompute),
+                ReadonlyArrayWrapper(Xy),
+                ReadonlyArrayWrapper(y),
                 max_iter,
                 tol,
                 rng,

From c1a4d96a6f1a09abd16c6f4fb47d40fc946dc0b3 Mon Sep 17 00:00:00 2001
From: Julien Jerphanion <git@jjerphan.xyz>
Date: Thu, 5 Jan 2023 14:15:11 +0100
Subject: [PATCH 05/12] MAINT Simplify and make copy of chunks of w

Co-authored-by: Thomas J. Fan <thomasjpfan@gmail.com>
---
 sklearn/decomposition/_dict_learning.py       |  2 ++
 .../decomposition/tests/test_dict_learning.py | 23 ++++++++-------
 sklearn/linear_model/_cd_fast.pyx             | 29 +++++++++----------
 sklearn/linear_model/_coordinate_descent.py   | 23 ++++++++-------
 4 files changed, 41 insertions(+), 36 deletions(-)

diff --git a/sklearn/decomposition/_dict_learning.py b/sklearn/decomposition/_dict_learning.py
index b0c252fc31698..e99465ada3b73 100644
--- a/sklearn/decomposition/_dict_learning.py
+++ b/sklearn/decomposition/_dict_learning.py
@@ -174,6 +174,8 @@ def _sparse_encode(
         )
 
         if init is not None:
+            if not init.flags["WRITEABLE"]:
+                init = np.array(init)
             clf.coef_ = init
 
         clf.fit(dictionary.T, X.T, check_input=check_input)
diff --git a/sklearn/decomposition/tests/test_dict_learning.py b/sklearn/decomposition/tests/test_dict_learning.py
index 5105062355fa2..24b73622c418a 100644
--- a/sklearn/decomposition/tests/test_dict_learning.py
+++ b/sklearn/decomposition/tests/test_dict_learning.py
@@ -5,6 +5,10 @@
 from functools import partial
 import itertools
 
+from joblib import Parallel
+
+import sklearn
+
 from sklearn.base import clone
 
 from sklearn.exceptions import ConvergenceWarning
@@ -1038,24 +1042,23 @@ def test_get_feature_names_out(estimator):
     )
 
 
-def test_cd_work_on_joblib_memmapped_data():
-    # Non-regression test for:
-    # https://github.com/scikit-learn/scikit-learn/issues/25165
-    # The Cython implementation of coordinate descent must work
-    # on readonly data.
+def test_cd_work_on_joblib_memmapped_data(monkeypatch):
+    monkeypatch.setattr(
+        sklearn.decomposition._dict_learning,
+        "Parallel",
+        partial(Parallel, max_nbytes=1000),
+    )
 
     rng = np.random.RandomState(0)
-    # This dataset is sufficient large to be memmapped by joblib
-    # and thus becomes readonly even if it originally isn't.
-    X_train = rng.randn(5000, 3072)
+    X_train = rng.randn(100, 10)
 
     dict_learner = DictionaryLearning(
-        n_components=56,
+        n_components=5,
         random_state=0,
         n_jobs=2,
         fit_algorithm="cd",
-        verbose=True,
         max_iter=50,
+        verbose=True,
     )
 
     # This must run and complete without error.
diff --git a/sklearn/linear_model/_cd_fast.pyx b/sklearn/linear_model/_cd_fast.pyx
index dc1c374d61f62..4ffa70161e602 100644
--- a/sklearn/linear_model/_cd_fast.pyx
+++ b/sklearn/linear_model/_cd_fast.pyx
@@ -92,12 +92,11 @@ cdef floating diff_abs_max(int n, floating* a, floating* b) nogil:
 
 
 def enet_coordinate_descent(
-    # TODO: const-qualify fused typed memoryview when Cython 3 is used (#23147)
-    cnp.ndarray[floating, ndim=1, mode='c']  w,
+    floating[::1] w,
     floating alpha,
     floating beta,
     floating[::1, :] X,
-    cnp.ndarray[floating, ndim=1, mode='c'] y,
+    floating[::1] y,
     unsigned int max_iter,
     floating tol,
     object rng,
@@ -275,16 +274,15 @@ def enet_coordinate_descent(
 
 
 def sparse_enet_coordinate_descent(
-    # TODO: const-qualify fused typed memoryview when Cython 3 is used (#23147)
-    cnp.ndarray[floating, ndim=1, mode='c'] w,
+    floating [::1] w,
     floating alpha,
     floating beta,
-    cnp.ndarray[floating, ndim=1, mode='c'] X_data,
+    floating[::1] X_data, # TODO: Make const after release of Cython 3 (#23147)
     const int[::1] X_indices,
     const int[::1] X_indptr,
-    cnp.ndarray[floating, ndim=1, mode='c'] y,
-    cnp.ndarray[floating, ndim=1, mode='c'] sample_weight,
-    cnp.ndarray[floating, ndim=1, mode='c'] X_mean,
+    floating[::1] y,
+    floating[::1] sample_weight,
+    floating[::1] X_mean,
     unsigned int max_iter,
     floating tol,
     object rng,
@@ -567,13 +565,12 @@ def sparse_enet_coordinate_descent(
 
 
 def enet_coordinate_descent_gram(
-    # TODO: const-qualify fused typed memoryview when Cython 3 is used (#23147)
-    floating[::1] w,
+    cnp.ndarray[floating, ndim=1, mode='c'] w,
     floating alpha,
     floating beta,
-    floating[:, ::1] Q,
-    floating[::1] q,
-    floating[:] y,
+    cnp.ndarray[floating, ndim=2, mode='c'] Q,
+    cnp.ndarray[floating, ndim=1, mode='c'] q,
+    cnp.ndarray[floating, ndim=1] y,
     unsigned int max_iter,
     floating tol,
     object rng,
@@ -739,10 +736,10 @@ def enet_coordinate_descent_gram(
 
 
 def enet_coordinate_descent_multi_task(
-    # TODO: const-qualify fused typed memoryview when Cython 3 is used (#23147)
-    cnp.ndarray[floating, ndim=2, mode='fortran'] W,
+    floating[::1, :] W,
     floating l1_reg,
     floating l2_reg,
+    # TODO: use const qualified fused-typed memoryview when Cython 3.0 is used.
     cnp.ndarray[floating, ndim=2, mode='fortran'] X,
     cnp.ndarray[floating, ndim=2, mode='fortran'] Y,
     unsigned int max_iter,
diff --git a/sklearn/linear_model/_coordinate_descent.py b/sklearn/linear_model/_coordinate_descent.py
index 54bb9072c12f4..67fffac39d466 100644
--- a/sklearn/linear_model/_coordinate_descent.py
+++ b/sklearn/linear_model/_coordinate_descent.py
@@ -30,7 +30,6 @@
     check_is_fitted,
     column_or_1d,
 )
-from ..utils._readonly_array_wrapper import ReadonlyArrayWrapper
 from ..utils.fixes import delayed
 
 # mypy error: Module 'sklearn.linear_model' has no attribute '_cd_fast'
@@ -594,9 +593,7 @@ def enet_path(
                 w=coef_,
                 alpha=l1_reg,
                 beta=l2_reg,
-                # TODO: remove ReadonlyArrayWrapper when const-qualify fused typed
-                # memoryviews are used (this necessiates Cython 3).
-                X_data=ReadonlyArrayWrapper(X.data),
+                X_data=X.data,
                 X_indices=X.indices,
                 X_indptr=X.indptr,
                 y=y,
@@ -618,14 +615,12 @@ def enet_path(
             if check_input:
                 precompute = check_array(precompute, dtype=X.dtype.type, order="C")
             model = cd_fast.enet_coordinate_descent_gram(
-                # TODO: remove ReadonlyArrayWrappers when const-qualify fused typed
-                # memoryviews are used (this necessiates Cython 3).
-                ReadonlyArrayWrapper(coef_),
+                coef_,
                 l1_reg,
                 l2_reg,
-                ReadonlyArrayWrapper(precompute),
-                ReadonlyArrayWrapper(Xy),
-                ReadonlyArrayWrapper(y),
+                precompute,
+                Xy,
+                y,
                 max_iter,
                 tol,
                 rng,
@@ -1886,6 +1881,14 @@ class LassoCV(RegressorMixin, LinearModelCV):
      :ref:`examples/linear_model/plot_lasso_model_selection.py
      <sphx_glr_auto_examples_linear_model_plot_lasso_model_selection.py>`.
 
+    :class:`LassoCV` leads to different results than a hyperparameter
+    search using :class:`~sklearn.model_selection.GridSearchCV` with a
+    :class:`Lasso` model. In :class:`LassoCV`, a model for a given
+    penalty `alpha` is warm started using the coefficients of the
+    closest model (trained at the previous iteration) on the
+    regularization path. It tends to speed up the hyperparameter
+    search.
+
     Examples
     --------
     >>> from sklearn.linear_model import LassoCV

From ad6058d041c4416f85c8e225be96396fcbcbde50 Mon Sep 17 00:00:00 2001
From: Julien Jerphanion <git@jjerphan.xyz>
Date: Thu, 5 Jan 2023 16:30:38 +0100
Subject: [PATCH 06/12] TST Make test_cd_work_on_joblib_memmapped_data faster
 to run

---
 sklearn/decomposition/tests/test_dict_learning.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/sklearn/decomposition/tests/test_dict_learning.py b/sklearn/decomposition/tests/test_dict_learning.py
index 24b73622c418a..16a695d1189ab 100644
--- a/sklearn/decomposition/tests/test_dict_learning.py
+++ b/sklearn/decomposition/tests/test_dict_learning.py
@@ -1046,11 +1046,11 @@ def test_cd_work_on_joblib_memmapped_data(monkeypatch):
     monkeypatch.setattr(
         sklearn.decomposition._dict_learning,
         "Parallel",
-        partial(Parallel, max_nbytes=1000),
+        partial(Parallel, max_nbytes=100),
     )
 
     rng = np.random.RandomState(0)
-    X_train = rng.randn(100, 10)
+    X_train = rng.randn(10, 10)
 
     dict_learner = DictionaryLearning(
         n_components=5,

From 160d6d5f31310bb4f40f00ddd4945b93970d4476 Mon Sep 17 00:00:00 2001
From: Julien Jerphanion <git@jjerphan.xyz>
Date: Thu, 5 Jan 2023 16:33:16 +0100
Subject: [PATCH 07/12] fixup! MAINT Simplify and make copy of chunks of w

---
 sklearn/linear_model/_coordinate_descent.py | 8 --------
 1 file changed, 8 deletions(-)

diff --git a/sklearn/linear_model/_coordinate_descent.py b/sklearn/linear_model/_coordinate_descent.py
index 67fffac39d466..9ecfd1c2740a5 100644
--- a/sklearn/linear_model/_coordinate_descent.py
+++ b/sklearn/linear_model/_coordinate_descent.py
@@ -1881,14 +1881,6 @@ class LassoCV(RegressorMixin, LinearModelCV):
      :ref:`examples/linear_model/plot_lasso_model_selection.py
      <sphx_glr_auto_examples_linear_model_plot_lasso_model_selection.py>`.
 
-    :class:`LassoCV` leads to different results than a hyperparameter
-    search using :class:`~sklearn.model_selection.GridSearchCV` with a
-    :class:`Lasso` model. In :class:`LassoCV`, a model for a given
-    penalty `alpha` is warm started using the coefficients of the
-    closest model (trained at the previous iteration) on the
-    regularization path. It tends to speed up the hyperparameter
-    search.
-
     Examples
     --------
     >>> from sklearn.linear_model import LassoCV

From 1200183c568e5f640007f8efbc5f878a8a847bec Mon Sep 17 00:00:00 2001
From: Julien Jerphanion <git@jjerphan.xyz>
Date: Thu, 5 Jan 2023 16:34:52 +0100
Subject: [PATCH 08/12] [scipy-dev] Trigger CI


From 5ad7565b25130392c4f5a10a38ced09a90bab4f3 Mon Sep 17 00:00:00 2001
From: Julien Jerphanion <git@jjerphan.xyz>
Date: Thu, 5 Jan 2023 17:22:38 +0100
Subject: [PATCH 09/12] [scipy-dev] TST cnp.ndarray all the way!

---
 sklearn/linear_model/_cd_fast.pyx | 24 +++++++++++++-----------
 1 file changed, 13 insertions(+), 11 deletions(-)

diff --git a/sklearn/linear_model/_cd_fast.pyx b/sklearn/linear_model/_cd_fast.pyx
index 4ffa70161e602..ba9b922461775 100644
--- a/sklearn/linear_model/_cd_fast.pyx
+++ b/sklearn/linear_model/_cd_fast.pyx
@@ -90,13 +90,13 @@ cdef floating diff_abs_max(int n, floating* a, floating* b) nogil:
             m = d
     return m
 
-
+# TODO: use const fused typed memoryview where possible when Cython 0.29.33 is used.
 def enet_coordinate_descent(
-    floating[::1] w,
+    cnp.ndarray[floating, ndim=1, mode='c'] w,
     floating alpha,
     floating beta,
-    floating[::1, :] X,
-    floating[::1] y,
+    cnp.ndarray[floating, ndim=2, mode='fortran'] X,
+    cnp.ndarray[floating, ndim=1, mode='c'] y,
     unsigned int max_iter,
     floating tol,
     object rng,
@@ -273,16 +273,17 @@ def enet_coordinate_descent(
     return np.asarray(w), gap, tol, n_iter + 1
 
 
+# TODO: use const fused typed memoryview where possible when Cython 0.29.33 is used.
 def sparse_enet_coordinate_descent(
-    floating [::1] w,
+    cnp.ndarray[floating, ndim=1, mode='c'] w,
     floating alpha,
     floating beta,
-    floating[::1] X_data, # TODO: Make const after release of Cython 3 (#23147)
+    cnp.ndarray[floating, ndim=1, mode='c'] X_data,
     const int[::1] X_indices,
     const int[::1] X_indptr,
-    floating[::1] y,
-    floating[::1] sample_weight,
-    floating[::1] X_mean,
+    cnp.ndarray[floating, ndim=1, mode='c'] y,
+    cnp.ndarray[floating, ndim=1, mode='c'] sample_weight,
+    cnp.ndarray[floating, ndim=1, mode='c'] X_mean,
     unsigned int max_iter,
     floating tol,
     object rng,
@@ -564,6 +565,7 @@ def sparse_enet_coordinate_descent(
     return np.asarray(w), gap, tol, n_iter + 1
 
 
+# TODO: use const fused typed memoryview where possible when Cython 0.29.33 is used.
 def enet_coordinate_descent_gram(
     cnp.ndarray[floating, ndim=1, mode='c'] w,
     floating alpha,
@@ -734,9 +736,9 @@ def enet_coordinate_descent_gram(
 
     return np.asarray(w), gap, tol, n_iter + 1
 
-
+# TODO: use const fused typed memoryview where possible when Cython 0.29.33 is used.
 def enet_coordinate_descent_multi_task(
-    floating[::1, :] W,
+    cnp.ndarray[floating, ndim=2, mode='fortran'] W,
     floating l1_reg,
     floating l2_reg,
     # TODO: use const qualified fused-typed memoryview when Cython 3.0 is used.

From bb4246f519e555d47de19e6ac0aac5dd91da2ac6 Mon Sep 17 00:00:00 2001
From: Julien Jerphanion <git@jjerphan.xyz>
Date: Fri, 6 Jan 2023 17:51:04 +0100
Subject: [PATCH 10/12] CI Trigger CI


From 4697e74fa59c78a74771b796bb5d89575e364105 Mon Sep 17 00:00:00 2001
From: Julien Jerphanion <git@jjerphan.xyz>
Date: Fri, 13 Jan 2023 10:39:56 +0100
Subject: [PATCH 11/12] DOC Document workaround

---
 sklearn/decomposition/_dict_learning.py | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/sklearn/decomposition/_dict_learning.py b/sklearn/decomposition/_dict_learning.py
index f497a4f8bcb80..34bc9cd63a4be 100644
--- a/sklearn/decomposition/_dict_learning.py
+++ b/sklearn/decomposition/_dict_learning.py
@@ -174,6 +174,11 @@ def _sparse_encode(
         )
 
         if init is not None:
+            # In some workflows using coordinate descent algorithms:
+            #  - users might provide NumPy arrays with read-only buffers
+            #  - `joblib` might memmap arrays making their buffer read-only
+            # TODO: move this handling (which is currently too broad)
+            # closer to the actual private function which need buffers to be writable.
             if not init.flags["WRITEABLE"]:
                 init = np.array(init)
             clf.coef_ = init

From 5595f7fc8f79779f5637f2747aa9ebb38b819e12 Mon Sep 17 00:00:00 2001
From: Julien Jerphanion <git@jjerphan.xyz>
Date: Fri, 13 Jan 2023 10:41:30 +0100
Subject: [PATCH 12/12] DOC Add a whats_new entry for 1.2.1

---
 doc/whats_new/v1.2.rst | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/doc/whats_new/v1.2.rst b/doc/whats_new/v1.2.rst
index 2795b21231779..e7db3c71d7fb5 100644
--- a/doc/whats_new/v1.2.rst
+++ b/doc/whats_new/v1.2.rst
@@ -22,6 +22,14 @@ Changelog
 - |Fix| Inheriting from :class:`base.TransformerMixin` will only wrap the `transform`
   method if the class defines `transform` itself. :pr:`25295` by `Thomas Fan`_.
 
+:mod:`sklearn.decomposition`
+............................
+
+- |Fix| :class:`decomposition.DictionaryLearning` better supports readonly NumPy
+  arrays. In particular, it better supports large datasets which are memory-mapped
+  when it is used with coordinate descent algorithms (i.e. when `fit_algorithm='cd'`).
+  :pr:`25172` by :user:`Julien Jerphanion <jjerphan>`.
+
 :mod:`sklearn.ensemble`
 .......................