From 3821e442eb9f56b367c2da7ed31cf0b665ac1c8e Mon Sep 17 00:00:00 2001
From: chenyu <chenyu@fastmail.com>
Date: Tue, 21 Apr 2026 20:24:38 -0400
Subject: [PATCH] _one_hot_along_dim and one_hot to mixin (#15861)

---
 test/null/test_tensor_uop_mixin.py |  5 +++++
 tinygrad/mixin/__init__.py         | 21 +++++++++++++++++++++
 tinygrad/tensor.py                 | 23 +----------------------
 3 files changed, 27 insertions(+), 22 deletions(-)

diff --git a/test/null/test_tensor_uop_mixin.py b/test/null/test_tensor_uop_mixin.py
index 286dea8ae6..bafc257253 100644
--- a/test/null/test_tensor_uop_mixin.py
+++ b/test/null/test_tensor_uop_mixin.py
@@ -62,6 +62,11 @@ class TestTensorUOpCumalu(unittest.TestCase):
   def test_cumsum_large(self):    _check(self, _t(600), lambda x: x.cumsum())  # exercises _split_cumalu
   def test_cumprod(self):         _check(self, _t(4), lambda x: x.cumprod(0))
 
+class TestTensorUOpOneHot(unittest.TestCase):
+  def test_one_hot(self):
+    t = _t(5)
+    self.assertIs(_strip_unique(t.one_hot(5).uop), _strip_unique(t.uop.one_hot(5)))
+
 class TestTensorUOpCat(unittest.TestCase):
   def test_cat_dim0(self):     _check(self, _t(2, 3), lambda x: x.cat(x, dim=0))
   def test_cat_dim1(self):     _check(self, _t(2, 3), lambda x: x.cat(x, dim=1))
diff --git a/tinygrad/mixin/__init__.py b/tinygrad/mixin/__init__.py
index 0108a7b575..cb32ded72e 100644
--- a/tinygrad/mixin/__init__.py
+++ b/tinygrad/mixin/__init__.py
@@ -575,6 +575,27 @@ class OpMixin(ElementwiseMixin, ReduceMixin):
     """
     return self._split_cumalu(axis, Ops.MUL)
 
+  # helper function commonly used for indexing
+  def _one_hot_along_dim(self, num_classes:sint, dim:int=-1) -> Self:
+    from tinygrad.uop.ops import sint_to_uop
+    if not dtypes.is_int(self.dtype): raise RuntimeError(f"_one_hot_along_dim expects int index tensor, getting {self.dtype}")
+    offset = self.ndim - self._resolve_dim(dim) - 1
+    dt = dtypes.int64 if sint_to_uop(num_classes).overflows(dtypes.int32) else dtypes.int32
+    return self.eq(type(self).arange(num_classes, dtype=dt, device=self.device).reshape((num_classes,) + (1,) * offset))
+
+  def one_hot(self, num_classes:int) -> Self:
+    """
+    Converts `self` to a one-hot tensor.
+
+    ```python exec="true" source="above" session="tensor" result="python"
+    t = Tensor([0, 1, 3, 3, 4])
+    print(t.one_hot(5).numpy())
+    ```
+    """
+    if not dtypes.is_int(self.dtype): raise RuntimeError(f"expect integer dtype, getting {self.dtype=}")
+    if num_classes < 0: raise ValueError(f"num_classes must be non-negative, got {num_classes}")
+    return self[..., None]._one_hot_along_dim(num_classes).where(1, 0)
+
   # ***** functional nn ops *****
 
   def linear(self, weight:Self, bias:Self|None=None, dtype:DTypeLike|None=None) -> Self:
diff --git a/tinygrad/tensor.py b/tinygrad/tensor.py
index 161eb6d8d9..c93ab490ea 100644
--- a/tinygrad/tensor.py
+++ b/tinygrad/tensor.py
@@ -11,8 +11,7 @@ from tinygrad.helpers import resolve_pool_pads, IMAGE, FLOAT16, WINO, Metadata,
 from tinygrad.helpers import suppress_finalizing, disable_gc
 from tinygrad.gradient import compute_gradient
 from tinygrad.mixin import OpMixin, ReductionStr
-from tinygrad.uop.ops import smax, UOp, Ops, sint, all_metadata, _index_to_concrete_int, sint_to_uop, Variable
-from tinygrad.uop.ops import _broadcast_shape
+from tinygrad.uop.ops import smax, UOp, Ops, sint, all_metadata, _index_to_concrete_int, Variable, _broadcast_shape
 from tinygrad.schedule import ExecItem, create_linear_with_vars, linear_to_schedule
 from tinygrad.device import Buffer, canonicalize_device
 from tinygrad.engine.realize import run_linear
@@ -2006,26 +2005,6 @@ class Tensor(OpMixin):
     if p == 1: return self.zeros_like()
     return (Tensor.rand_like(self, requires_grad=False, dtype=dtypes.default_float, contiguous=False) >= p).contiguous().where(self, 0) / (1.0 - p)
 
-  # helper function commonly used for indexing
-  def _one_hot_along_dim(self:Tensor, num_classes:sint, dim:int=-1) -> Tensor:
-    if not dtypes.is_int(self.dtype): raise RuntimeError(f"_one_hot_along_dim expects int index tensor, getting {self.dtype}")
-    offset = self.ndim - self._resolve_dim(dim) - 1
-    dt = dtypes.int64 if sint_to_uop(num_classes).overflows(dtypes.int32) else dtypes.int32
-    return self == Tensor.arange(num_classes, dtype=dt, device=self.device, requires_grad=False).reshape((num_classes,) + (1,) * offset)
-
-  def one_hot(self, num_classes:int) -> Tensor:
-    """
-    Converts `self` to a one-hot tensor.
-
-    ```python exec="true" source="above" session="tensor" result="python"
-    t = Tensor([0, 1, 3, 3, 4])
-    print(t.one_hot(5).numpy())
-    ```
-    """
-    if not dtypes.is_int(self.dtype): raise RuntimeError(f"expect integer dtype, getting {self.dtype=}")
-    if num_classes < 0: raise ValueError(f"num_classes must be non-negative, got {num_classes}")
-    return self[..., None]._one_hot_along_dim(num_classes).where(1, 0)
-
   def scaled_dot_product_attention(self, key:Tensor, value:Tensor, attn_mask:Tensor|None=None, dropout_p:float=0.0,
                                    is_causal:bool=False, enable_gqa:bool=False) -> Tensor:
     """