feat(mge/functional): argmin and argmax support negtive axis

GitOrigin-RevId: a1bd1102a6

imperative/python/megengine/core/tensor/array_method.py

@@ -165,7 +165,7 @@ def _remove_axis(inp: Tensor, axis) -> Tensor:
         return list(map(int, axis))
 
     axis = get_axes()
-    axis = sorted(i + inp.ndim if i < 0 else i for i in axis)
+    axis = utils._normalize_axis(inp.ndim, axis)
     axis = [a - i for i, a in enumerate(axis)]
 
     op = builtin.RemoveAxis(axis=axis)
@@ -190,8 +190,7 @@ def _reduce(mode):
             op = builtin.Reduce(mode=mode, axis=0)
             (result,) = apply(op, data)
         elif isinstance(axis, collections.abc.Iterable):
-            axis = list(axis)
-            axis.sort(reverse=True)
+            axis = utils._normalize_axis(self.ndim, axis, reverse=True)
             for ai in axis:
                 op = builtin.Reduce(mode=mode, axis=ai)
                 (data,) = apply(op, data)
@@ -199,6 +198,7 @@ def _reduce(mode):
                     data = _remove_axis(data, ai)
             result = data
         else:
+            # builtin.Reduce already accept negtive axis
             op = builtin.Reduce(mode=mode, axis=axis)
             (result,) = apply(op, data)
 

imperative/python/megengine/core/tensor/utils.py

@@ -178,3 +178,28 @@ def make_shape_tuple(shape):
     s = []
     _expand_int(s, shape)
     return tuple(s)
+
+
+def _normalize_axis(
+    ndim: int, axis: Union[int, Iterable], reverse=False
+) -> Union[int, list]:
+    def convert(x):
+        x_org = x
+        if x < 0:
+            x = ndim + x
+        assert (
+            x >= 0 and x < ndim
+        ), "axis {} is out of bounds for tensor of dimension {}".format(x_org, ndim)
+        return x
+
+    if isinstance(axis, int):
+        return convert(axis)
+    elif isinstance(axis, Iterable):
+        axis_org = axis
+        axis = list(sorted(map(convert, axis), reverse=reverse))
+        for i in range(len(axis) - 1):
+            assert axis[i] != axis[i + 1], "axis {} contains duplicated indices".format(
+                axis_org
+            )
+        return axis
+    raise

imperative/python/megengine/functional/math.py

@@ -466,9 +466,13 @@ def argmin(
         0
 
     """
+    if axis is None:
+        assert not keepdims, "can not set axis=None and keepdims=True"
+        inp = inp.flatten()
+        axis = 0
+
+    axis = utils._normalize_axis(inp.ndim, axis, reverse=True)
     if isinstance(axis, collections.abc.Iterable):
-        axis = list(axis)
-        axis.sort(reverse=True)
 
         for ai in axis:
             op = builtin.Argmin(axis=ai)
@@ -479,11 +483,6 @@ def argmin(
 
         return inp
 
-    if axis is None:
-        assert not keepdims, "can not set axis=None and keepdims=True"
-        inp = inp.flatten()
-        axis = 0
-
     op = builtin.Argmin(axis=axis)
     (result,) = apply(op, inp)
     if not keepdims:
@@ -525,9 +524,13 @@ def argmax(
         5
 
     """
+    if axis is None:
+        assert not keepdims, "can not set axis=None and keepdims=True"
+        inp = inp.flatten()
+        axis = 0
+    axis = utils._normalize_axis(inp.ndim, axis, reverse=True)
+
     if isinstance(axis, collections.abc.Iterable):
-        axis = list(axis)
-        axis.sort(reverse=True)
 
         for ai in axis:
             op = builtin.Argmax(axis=ai)
@@ -538,11 +541,6 @@ def argmax(
 
         return inp
 
-    if axis is None:
-        assert not keepdims, "can not set axis=None and keepdims=True"
-        inp = inp.flatten()
-        axis = 0
-
     op = builtin.Argmax(axis=axis)
     (result,) = apply(op, inp)
     if not keepdims:

imperative/python/test/unit/functional/test_functional.py

@@ -811,3 +811,19 @@ def test_assert_not_equal():
     y = F.zeros(shape, dtype=np.float32) + 1.1
     with pytest.raises(RuntimeError):
         z = F.utils._assert_equal(x, y)
+
+
+def test_neg_axis():
+    x = tensor(np.random.normal(0, 1, (32, 5)))
+
+    y = F.argmax(x, axis=-1)
+    yy = F.argmax(x, axis=1)
+    np.testing.assert_equal(y.numpy(), yy.numpy())
+
+    y = F.argmax(x, axis=(-1, -2))
+    yy = F.argmax(x, axis=(0, 1))
+    np.testing.assert_equal(y.numpy(), yy.numpy())
+
+    y = F.argmin(x, axis=(-1, -2))
+    yy = F.argmin(x, axis=(0, 1))
+    np.testing.assert_equal(y.numpy(), yy.numpy())

imperative/python/test/unit/functional/test_math.py

@@ -9,6 +9,7 @@
 from functools import partial
 
 import numpy as np
+import pytest
 from utils import opr_test
 
 import megengine.functional as F
@@ -48,6 +49,14 @@ def common_test_reduce(opr, ref_opr):
                 ref_fn=lambda x: ref_opr(x, axis=axis).astype(np.int32),
                 axis=axis,
             )
+            # test negative axis
+            axis = axis - len(data1_shape)
+            opr_test(
+                cases,
+                opr,
+                ref_fn=lambda x: ref_opr(x, axis=axis).astype(np.int32),
+                axis=axis,
+            )
 
 
 def test_sum():
@@ -137,3 +146,14 @@ def test_normalize():
     cases[0]["input"][0, 0, 0, :] = 0
     cases[1]["input"][0, 0, 0, :] = 0
     opr_test(cases, partial(F.normalize, axis=3), ref_fn=partial(np_normalize, axis=3))
+
+
+def test_sum_neg_axis():
+    shape = (2, 3)
+    data = np.random.random(shape).astype(np.float32)
+    for axis in (-1, -2, (-2, 1), (-1, 0)):
+        get = F.sum(tensor(data), axis=axis)
+        ref = np.sum(data, axis=axis)
+        np.testing.assert_allclose(get.numpy(), ref, rtol=1e-6)
+    with pytest.raises(AssertionError):
+        F.sum(tensor(data), axis=(-1, 1))