From d0d485c4aeea315bb6effc25334a0ab298229ca3 Mon Sep 17 00:00:00 2001
From: ArturoAmorQ <arturo.amor-quiroz@polytechnique.edu>
Date: Fri, 15 Oct 2021 12:07:58 +0200
Subject: [PATCH 01/15] Add validation on alpha

---
 sklearn/linear_model/_ridge.py | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/sklearn/linear_model/_ridge.py b/sklearn/linear_model/_ridge.py
index 1dcc81e3b988f..7bf2548de9ca3 100644
--- a/sklearn/linear_model/_ridge.py
+++ b/sklearn/linear_model/_ridge.py
@@ -13,6 +13,7 @@
 import warnings
 
 import numpy as np
+import numbers
 from scipy import linalg
 from scipy import sparse
 from scipy import optimize
@@ -26,6 +27,7 @@
 from ..utils.extmath import row_norms
 from ..utils import check_array
 from ..utils import check_consistent_length
+from ..utils import check_scalar
 from ..utils import compute_sample_weight
 from ..utils import column_or_1d
 from ..utils.validation import _check_sample_weight
@@ -564,8 +566,11 @@ def _ridge_regression(
             % (alpha.size, n_targets)
         )
 
-    if alpha.size == 1 and n_targets > 1:
-        alpha = np.repeat(alpha, n_targets)
+    if alpha.size == 1:
+        check_scalar(alpha, "alpha", target_type=numbers.Real,
+                     min_val=0.0, include_boundaries="left")
+        if n_targets > 1:
+            alpha = np.repeat(alpha, n_targets)
 
     n_iter = None
     if solver == "sparse_cg":

From 553143d6ea75b1700eada58e2fe2dfdb02664788 Mon Sep 17 00:00:00 2001
From: ArturoAmorQ <arturo.amor-quiroz@polytechnique.edu>
Date: Tue, 19 Oct 2021 11:36:48 +0200
Subject: [PATCH 02/15] Modify alpha inplace for validation

---
 sklearn/linear_model/_ridge.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/sklearn/linear_model/_ridge.py b/sklearn/linear_model/_ridge.py
index 7bf2548de9ca3..bf507f5b95d17 100644
--- a/sklearn/linear_model/_ridge.py
+++ b/sklearn/linear_model/_ridge.py
@@ -567,8 +567,8 @@ def _ridge_regression(
         )
 
     if alpha.size == 1:
-        check_scalar(alpha, "alpha", target_type=numbers.Real,
-                     min_val=0.0, include_boundaries="left")
+        alpha[0] = check_scalar(alpha[0], "alpha", target_type=numbers.Real,
+                   min_val=0.0, include_boundaries="left")
         if n_targets > 1:
             alpha = np.repeat(alpha, n_targets)
 

From eb77f3585202c17c7a2552cf2442274e7cbb6230 Mon Sep 17 00:00:00 2001
From: ArturoAmorQ <arturo.amor-quiroz@polytechnique.edu>
Date: Tue, 19 Oct 2021 13:42:27 +0200
Subject: [PATCH 03/15] Format code with pre-commit config

---
 sklearn/linear_model/_ridge.py | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/sklearn/linear_model/_ridge.py b/sklearn/linear_model/_ridge.py
index bf507f5b95d17..8410dd37a1e7c 100644
--- a/sklearn/linear_model/_ridge.py
+++ b/sklearn/linear_model/_ridge.py
@@ -567,8 +567,13 @@ def _ridge_regression(
         )
 
     if alpha.size == 1:
-        alpha[0] = check_scalar(alpha[0], "alpha", target_type=numbers.Real,
-                   min_val=0.0, include_boundaries="left")
+        alpha[0] = check_scalar(
+            alpha[0],
+            "alpha",
+            target_type=numbers.Real,
+            min_val=0.0,
+            include_boundaries="left",
+        )
         if n_targets > 1:
             alpha = np.repeat(alpha, n_targets)
 

From c55bb551ba3441d5288e74fc62a7963ef0ad3710 Mon Sep 17 00:00:00 2001
From: ArturoAmorQ <arturo.amor-quiroz@polytechnique.edu>
Date: Wed, 20 Oct 2021 11:13:17 +0200
Subject: [PATCH 04/15] Validate max_iter for Ridge

Also corrects validation for alpha
---
 sklearn/linear_model/_ridge.py | 26 ++++++++++++++++----------
 1 file changed, 16 insertions(+), 10 deletions(-)

diff --git a/sklearn/linear_model/_ridge.py b/sklearn/linear_model/_ridge.py
index 8410dd37a1e7c..d055c91193f89 100644
--- a/sklearn/linear_model/_ridge.py
+++ b/sklearn/linear_model/_ridge.py
@@ -558,6 +558,15 @@ def _ridge_regression(
             # we implement sample_weight via a simple rescaling.
             X, y = _rescale_data(X, y, sample_weight)
 
+    if not isinstance(alpha, (np.ndarray, type(None), tuple)):
+        alpha = check_scalar(
+            alpha,
+            "alpha",
+            target_type=numbers.Real,
+            min_val=0.0,
+            include_boundaries="left",
+        )
+
     # There should be either 1 or n_targets penalties
     alpha = np.asarray(alpha, dtype=X.dtype).ravel()
     if alpha.size not in [1, n_targets]:
@@ -566,16 +575,8 @@ def _ridge_regression(
             % (alpha.size, n_targets)
         )
 
-    if alpha.size == 1:
-        alpha[0] = check_scalar(
-            alpha[0],
-            "alpha",
-            target_type=numbers.Real,
-            min_val=0.0,
-            include_boundaries="left",
-        )
-        if n_targets > 1:
-            alpha = np.repeat(alpha, n_targets)
+    if alpha.size == 1 and n_targets > 1:
+        alpha = np.repeat(alpha, n_targets)
 
     n_iter = None
     if solver == "sparse_cg":
@@ -761,6 +762,11 @@ def fit(self, X, y, sample_weight=None):
         if sample_weight is not None:
             sample_weight = _check_sample_weight(sample_weight, X, dtype=X.dtype)
 
+        if self.max_iter is not None:
+            self.max_iter = check_scalar(
+                self.max_iter, "max_iter", target_type=numbers.Integral, min_val=1
+            )
+
         # when X is sparse we only remove offset from y
         X, y, X_offset, y_offset, X_scale = self._preprocess_data(
             X,

From 88a22442f87a2c03c4fee9f1c8c3b75a79b90433 Mon Sep 17 00:00:00 2001
From: ArturoAmorQ <arturo.amor-quiroz@polytechnique.edu>
Date: Wed, 20 Oct 2021 12:01:55 +0200
Subject: [PATCH 05/15] Add tests for alpha and max_iter validation

---
 sklearn/linear_model/tests/test_ridge.py | 30 ++++++++++++++++++++++++
 1 file changed, 30 insertions(+)

diff --git a/sklearn/linear_model/tests/test_ridge.py b/sklearn/linear_model/tests/test_ridge.py
index bfc6722737bd8..a24d3c222cace 100644
--- a/sklearn/linear_model/tests/test_ridge.py
+++ b/sklearn/linear_model/tests/test_ridge.py
@@ -335,6 +335,36 @@ def test_ridge_individual_penalties():
         ridge.fit(X, y)
 
 
+@pytest.mark.parametrize(
+    "params, err_type, err_msg",
+    [
+        ({"alpha": -1}, ValueError, "alpha == -1, must be >= 0.0"),
+        (
+            {"alpha": "1"},
+            TypeError,
+            "alpha must be an instance of <class 'numbers.Real'>, not <class 'str'>",
+        ),
+        ({"max_iter": 0}, ValueError, "max_iter == 0, must be >= 1."),
+        (
+            {"max_iter": "1"},
+            TypeError,
+            "max_iter must be an instance of <class 'numbers.Integral'>, not <class"
+            " 'str'>",
+        ),
+    ],
+)
+def test_Ridge_params_validation(params, err_type, err_msg):
+    """Check the parameters validation in `Ridge`."""
+
+    rng = np.random.RandomState(42)
+    n_samples, n_features, n_targets = 20, 10, 5
+    X = rng.randn(n_samples, n_features)
+    y = rng.randn(n_samples, n_targets)
+
+    with pytest.raises(err_type, match=err_msg):
+        Ridge(**params).fit(X, y)
+
+
 @pytest.mark.parametrize("n_col", [(), (1,), (3,)])
 def test_X_CenterStackOp(n_col):
     rng = np.random.RandomState(0)

From 1475fd098df4b7c54380808a86e654c916e64225 Mon Sep 17 00:00:00 2001
From: ArturoAmorQ <arturo.amor-quiroz@polytechnique.edu>
Date: Wed, 20 Oct 2021 16:20:36 +0200
Subject: [PATCH 06/15] Validate tol for Ridge

---
 sklearn/linear_model/_ridge.py | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/sklearn/linear_model/_ridge.py b/sklearn/linear_model/_ridge.py
index d055c91193f89..5c4f15525f355 100644
--- a/sklearn/linear_model/_ridge.py
+++ b/sklearn/linear_model/_ridge.py
@@ -767,6 +767,8 @@ def fit(self, X, y, sample_weight=None):
                 self.max_iter, "max_iter", target_type=numbers.Integral, min_val=1
             )
 
+        self.tol = check_scalar(self.tol, "tol", target_type=float, min_val=0.0)
+
         # when X is sparse we only remove offset from y
         X, y, X_offset, y_offset, X_scale = self._preprocess_data(
             X,

From fe56c15a7130db03e4bd5ca9f2db9edc9e66ce39 Mon Sep 17 00:00:00 2001
From: ArturoAmorQ <arturo.amor-quiroz@polytechnique.edu>
Date: Wed, 20 Oct 2021 16:23:01 +0200
Subject: [PATCH 07/15] Add tests for tol validation

---
 sklearn/linear_model/tests/test_ridge.py | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/sklearn/linear_model/tests/test_ridge.py b/sklearn/linear_model/tests/test_ridge.py
index a24d3c222cace..7a438af3afab3 100644
--- a/sklearn/linear_model/tests/test_ridge.py
+++ b/sklearn/linear_model/tests/test_ridge.py
@@ -351,6 +351,17 @@ def test_ridge_individual_penalties():
             "max_iter must be an instance of <class 'numbers.Integral'>, not <class"
             " 'str'>",
         ),
+        ({"tol": -1.0}, ValueError, "tol == -1.0, must be >= 0."),
+        (
+            {"tol": 1},
+            TypeError,
+            "tol must be an instance of <class 'float'>, not <class 'int'>",
+        ),
+        (
+            {"tol": "1"},
+            TypeError,
+            "tol must be an instance of <class 'float'>, not <class 'str'>",
+        ),
     ],
 )
 def test_Ridge_params_validation(params, err_type, err_msg):

From f427dc257483f52260c49837da3488069e9133fd Mon Sep 17 00:00:00 2001
From: ArturoAmor <86408019+ArturoAmorQ@users.noreply.github.com>
Date: Wed, 10 Nov 2021 15:35:33 +0100
Subject: [PATCH 08/15] Update sklearn/linear_model/_ridge.py

This change is indeed independent of `RidgeCV`. This commit adds an explanation on the need for a conditional statement during validation.

Co-authored-by: Julien Jerphanion <git@jjerphan.xyz>
---
 sklearn/linear_model/_ridge.py | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/sklearn/linear_model/_ridge.py b/sklearn/linear_model/_ridge.py
index 5c4f15525f355..cf95eb9c31dbc 100644
--- a/sklearn/linear_model/_ridge.py
+++ b/sklearn/linear_model/_ridge.py
@@ -558,6 +558,8 @@ def _ridge_regression(
             # we implement sample_weight via a simple rescaling.
             X, y = _rescale_data(X, y, sample_weight)
 
+    # Some callers of this method might pass alpha as single
+    # element array which already has been validated.
     if not isinstance(alpha, (np.ndarray, type(None), tuple)):
         alpha = check_scalar(
             alpha,

From 4c0bce27a640c9faf80fc3ea2a22afe8883c2b65 Mon Sep 17 00:00:00 2001
From: ArturoAmor <86408019+ArturoAmorQ@users.noreply.github.com>
Date: Wed, 10 Nov 2021 15:36:41 +0100
Subject: [PATCH 09/15] Update sklearn/linear_model/tests/test_ridge.py

Tweak to adopt conventions

Co-authored-by: Julien Jerphanion <git@jjerphan.xyz>
---
 sklearn/linear_model/tests/test_ridge.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/sklearn/linear_model/tests/test_ridge.py b/sklearn/linear_model/tests/test_ridge.py
index 7a438af3afab3..45d24bc87c045 100644
--- a/sklearn/linear_model/tests/test_ridge.py
+++ b/sklearn/linear_model/tests/test_ridge.py
@@ -364,8 +364,8 @@ def test_ridge_individual_penalties():
         ),
     ],
 )
-def test_Ridge_params_validation(params, err_type, err_msg):
-    """Check the parameters validation in `Ridge`."""
+def test_ridge_params_validation(params, err_type, err_msg):
+    """Check the parameters validation in Ridge."""
 
     rng = np.random.RandomState(42)
     n_samples, n_features, n_targets = 20, 10, 5

From d397336670547d1363a0b821598285ae6c62b14f Mon Sep 17 00:00:00 2001
From: ArturoAmor <86408019+ArturoAmorQ@users.noreply.github.com>
Date: Mon, 22 Nov 2021 15:22:55 +0100
Subject: [PATCH 10/15] Improve readability

Co-authored-by: Olivier Grisel <olivier.grisel@ensta.org>
---
 sklearn/linear_model/_ridge.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/sklearn/linear_model/_ridge.py b/sklearn/linear_model/_ridge.py
index cf95eb9c31dbc..015734d7a51c1 100644
--- a/sklearn/linear_model/_ridge.py
+++ b/sklearn/linear_model/_ridge.py
@@ -560,7 +560,7 @@ def _ridge_regression(
 
     # Some callers of this method might pass alpha as single
     # element array which already has been validated.
-    if not isinstance(alpha, (np.ndarray, type(None), tuple)):
+    if alpha is not None and not isinstance(alpha, (np.ndarray, tuple)):
         alpha = check_scalar(
             alpha,
             "alpha",

From 113bdf2982c65609c9c42e1acfa4f835e408bb77 Mon Sep 17 00:00:00 2001
From: ArturoAmorQ <arturo.amor-quiroz@polytechnique.edu>
Date: Mon, 22 Nov 2021 16:02:51 +0100
Subject: [PATCH 11/15] Change `tol` from <class 'float'> to <class
 'numbers.Real'>

---
 sklearn/linear_model/_ridge.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/sklearn/linear_model/_ridge.py b/sklearn/linear_model/_ridge.py
index 015734d7a51c1..7b12f7f972668 100644
--- a/sklearn/linear_model/_ridge.py
+++ b/sklearn/linear_model/_ridge.py
@@ -769,7 +769,7 @@ def fit(self, X, y, sample_weight=None):
                 self.max_iter, "max_iter", target_type=numbers.Integral, min_val=1
             )
 
-        self.tol = check_scalar(self.tol, "tol", target_type=float, min_val=0.0)
+        self.tol = check_scalar(self.tol, "tol", target_type=numbers.Real, min_val=0.0)
 
         # when X is sparse we only remove offset from y
         X, y, X_offset, y_offset, X_scale = self._preprocess_data(

From 16a52f1d683d2966ebe852b55d29553a4b288de1 Mon Sep 17 00:00:00 2001
From: ArturoAmorQ <arturo.amor-quiroz@polytechnique.edu>
Date: Mon, 22 Nov 2021 16:05:37 +0100
Subject: [PATCH 12/15] Edit tests to accept `tol` in <class 'float'>

---
 sklearn/linear_model/tests/test_ridge.py | 7 +------
 1 file changed, 1 insertion(+), 6 deletions(-)

diff --git a/sklearn/linear_model/tests/test_ridge.py b/sklearn/linear_model/tests/test_ridge.py
index 45d24bc87c045..e73c3e82321f9 100644
--- a/sklearn/linear_model/tests/test_ridge.py
+++ b/sklearn/linear_model/tests/test_ridge.py
@@ -352,15 +352,10 @@ def test_ridge_individual_penalties():
             " 'str'>",
         ),
         ({"tol": -1.0}, ValueError, "tol == -1.0, must be >= 0."),
-        (
-            {"tol": 1},
-            TypeError,
-            "tol must be an instance of <class 'float'>, not <class 'int'>",
-        ),
         (
             {"tol": "1"},
             TypeError,
-            "tol must be an instance of <class 'float'>, not <class 'str'>",
+            "tol must be an instance of <class 'numbers.Real'>, not <class 'str'>",
         ),
     ],
 )

From 91bec921e80ae5e91d49a9322e495e00cc0566cd Mon Sep 17 00:00:00 2001
From: ArturoAmorQ <arturo.amor-quiroz@polytechnique.edu>
Date: Mon, 22 Nov 2021 16:08:17 +0100
Subject: [PATCH 13/15] Add changelog entry in `doc/whats_new/v1.1.rst`

---
 doc/whats_new/v1.1.rst | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/doc/whats_new/v1.1.rst b/doc/whats_new/v1.1.rst
index a473908d8f1e7..621d9331e70da 100644
--- a/doc/whats_new/v1.1.rst
+++ b/doc/whats_new/v1.1.rst
@@ -68,6 +68,12 @@ Changelog
   message when the solver does not support sparse matrices with int64 indices.
   :pr:`21093` by `Tom Dupre la Tour`_.
 
+- |Enhancement| :class:`linear_model.Ridge` and :class:`linear_model.RidgeClassifier`
+  now raise consistent error message when passed invalid values for `alpha`,
+  `max_iter` and `tol`.
+  :pr:`21341` by :user:`Arturo Amor <ArturoAmorQ>`
+  and :user:`Julien Jerphanion <jjerphan>`.
+
 :mod:`sklearn.metrics`
 ......................
 

From c4659e588dd43cfc58c51d47b313270305f5ebdd Mon Sep 17 00:00:00 2001
From: Arturo Amor <86408019+ArturoAmorQ@users.noreply.github.com>
Date: Wed, 1 Dec 2021 09:43:51 +0100
Subject: [PATCH 14/15] Update doc/whats_new/v1.1.rst

Co-authored-by: Julien Jerphanion <git@jjerphan.xyz>
---
 doc/whats_new/v1.1.rst | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/doc/whats_new/v1.1.rst b/doc/whats_new/v1.1.rst
index 6b83b7b95d7a8..2973213bb8e96 100644
--- a/doc/whats_new/v1.1.rst
+++ b/doc/whats_new/v1.1.rst
@@ -144,8 +144,7 @@ Changelog
 - |Enhancement| :class:`linear_model.Ridge` and :class:`linear_model.RidgeClassifier`
   now raise consistent error message when passed invalid values for `alpha`,
   `max_iter` and `tol`.
-  :pr:`21341` by :user:`Arturo Amor <ArturoAmorQ>`
-  and :user:`Julien Jerphanion <jjerphan>`.
+  :pr:`21341` by :user:`Arturo Amor <ArturoAmorQ>`.
 
 :mod:`sklearn.metrics`
 ......................

From 47fd0bd5268529c028341b6fd7443744f97fcce9 Mon Sep 17 00:00:00 2001
From: ArturoAmorQ <arturo.amor-quiroz@polytechnique.edu>
Date: Wed, 1 Dec 2021 09:55:27 +0100
Subject: [PATCH 15/15] tweak

---
 doc/whats_new/v1.1.rst | 1 +
 1 file changed, 1 insertion(+)

diff --git a/doc/whats_new/v1.1.rst b/doc/whats_new/v1.1.rst
index c1270d28bf80f..b9651a1e1b6f8 100644
--- a/doc/whats_new/v1.1.rst
+++ b/doc/whats_new/v1.1.rst
@@ -191,6 +191,7 @@ Changelog
   now raise consistent error message when passed invalid values for `alpha`,
   `max_iter` and `tol`.
   :pr:`21341` by :user:`Arturo Amor <ArturoAmorQ>`.
+
 :mod:`sklearn.linear_model`
 ...........................