From 9ee9f3dc92ceb803eaf89c4504600f39e5e9f38d Mon Sep 17 00:00:00 2001
From: Dimitri Papadopoulos
 <3234522+DimitriPapadopoulos@users.noreply.github.com>
Date: Sat, 28 Jun 2025 10:10:43 +0200
Subject: [PATCH 1/3] Ignore ruff/Pylint rule PLR0124

PLR0124 Name compared with itself
---
 pyproject.toml                | 2 ++
 xarray/core/duck_array_ops.py | 2 +-
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/pyproject.toml b/pyproject.toml
index 36170540135..a18161e88ee 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -293,6 +293,8 @@ ignore = [
 [tool.ruff.lint.per-file-ignores]
 # don't enforce absolute imports
 "asv_bench/**" = ["TID252"]
+# comparison with itself in tests
+"xarray/tests/**" = ["PLR0124"]
 # looks like ruff bugs
 "xarray/core/_typed_ops.py" = ["PYI034"]
 "xarray/namedarray/_typing.py" = ["PYI018", "PYI046"]
diff --git a/xarray/core/duck_array_ops.py b/xarray/core/duck_array_ops.py
index e98ac0f36a1..35f3b425697 100644
--- a/xarray/core/duck_array_ops.py
+++ b/xarray/core/duck_array_ops.py
@@ -193,7 +193,7 @@ def isnull(data):
         # types. For full consistency with pandas, we should accept None as
         # a null value as well as NaN, but it isn't clear how to do this
         # with duck typing.
-        return data != data
+        return data != data  # noqa: PLR0124
 
 
 def notnull(data):

From b34c22a9eafc9348e967a6ea16df0616c6ebfe8e Mon Sep 17 00:00:00 2001
From: Dimitri Papadopoulos
 <3234522+DimitriPapadopoulos@users.noreply.github.com>
Date: Sat, 28 Jun 2025 10:14:00 +0200
Subject: [PATCH 2/3] Apply ruff/Pylint rule PLR5501

PLR5501 Use `elif` instead of `else` then `if`, to reduce indentation
---
 xarray/coding/strings.py | 17 ++++++++---------
 1 file changed, 8 insertions(+), 9 deletions(-)

diff --git a/xarray/coding/strings.py b/xarray/coding/strings.py
index c917faaf383..8fba967240c 100644
--- a/xarray/coding/strings.py
+++ b/xarray/coding/strings.py
@@ -129,15 +129,14 @@ def validate_char_dim_name(strlen, encoding, name) -> str:
                     "To silence this warning either remove 'char_dim_name' from encoding or provide a fitting name."
                 )
             char_dim_name = f"{new_dim_name}{strlen}"
-        else:
-            if (
-                original_shape := encoding.get("original_shape", [-1])[-1]
-            ) != -1 and original_shape != strlen:
-                emit_user_level_warning(
-                    f"String dimension length mismatch on variable {name!r}. '{original_shape}' provided by encoding, but data has length of '{strlen}'. Using '{char_dim_name}{strlen}' instead of {char_dim_name!r} to prevent possible naming clash.\n"
-                    f"To silence this warning remove 'original_shape' from encoding."
-                )
-                char_dim_name = f"{char_dim_name}{strlen}"
+        elif (
+            original_shape := encoding.get("original_shape", [-1])[-1]
+        ) != -1 and original_shape != strlen:
+            emit_user_level_warning(
+                f"String dimension length mismatch on variable {name!r}. '{original_shape}' provided by encoding, but data has length of '{strlen}'. Using '{char_dim_name}{strlen}' instead of {char_dim_name!r} to prevent possible naming clash.\n"
+                f"To silence this warning remove 'original_shape' from encoding."
+            )
+            char_dim_name = f"{char_dim_name}{strlen}"
     else:
         char_dim_name = f"string{strlen}"
 

From 927ff721dac37914c87572f9bc10b21282e35425 Mon Sep 17 00:00:00 2001
From: Dimitri Papadopoulos
 <3234522+DimitriPapadopoulos@users.noreply.github.com>
Date: Sat, 28 Jun 2025 10:17:15 +0200
Subject: [PATCH 3/3] Enforce ruff/Pylint Refactor rules (PLR)

---
 pyproject.toml | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/pyproject.toml b/pyproject.toml
index a18161e88ee..f303623d553 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -261,6 +261,7 @@ extend-select = [
   "W",    # pycodestyle warnings
   "PGH",  # pygrep-hooks
   "PLE",  # Pylint Errors
+  "PLR",  # Pylint Refactor
   "PLW",  # Pylint Warnings
   "UP",   # pyupgrade
   "FURB", # refurb
@@ -277,6 +278,8 @@ ignore = [
   "PERF203", # try-except within a loop incurs performance overhead
   "E402",    # module level import not at top of file
   "E731",    # do not assign a lambda expression, use a def
+  "PLR091",  # too many arguments / branches / statements
+  "PLR2004", # magic value used in comparison
   "PLW0603", # using the global statement to update is discouraged
   "PLW0642", # reassigned `self` variable in instance method
   "PLW1641", # object does not implement `__hash__` method