[TOPI] add squeeze (#494)

* add squeeze

* should be squeeze

topi/python/topi/transform.py

@@ -3,7 +3,7 @@
 from __future__ import absolute_import as _abs
 import tvm
 from . import tag
-from .util import ravel_index, unravel_index, get_const_int
+from .util import ravel_index, unravel_index, get_const_int, get_const_tuple
 
 @tvm.tag_scope(tag=tag.BROADCAST)
 def expand_dims(a, axis, num_newaxis=1):
@@ -77,6 +77,57 @@ def reshape(a, newshape):
                        lambda *indices: a(*unravel_index(ravel_index(indices, newshape), a_shape)))
 
 
+@tvm.tag_scope(tag=tag.INJECTIVE)
+def squeeze(a, axis=None):
+    """Remove single-dimensional entries from the shape of an array.
+
+    Parameters
+    ----------
+    a : tvm.Tensor
+
+    axis : None or int or tuple of ints, optional
+        Selects a subset of the single-dimensional entries in the shape.
+        If an axis is selected with shape entry greater than one, an error is raised.
+
+    Returns
+    -------
+    squeezed : tvm.Tensor
+    """
+    a_ndim = len(a.shape)
+    a_shape = get_const_tuple(a.shape)
+    if axis is None:
+        axis = []
+        for i, ele in enumerate(a_shape):
+            if ele == 1:
+                axis.append(i)
+    else:
+        if isinstance(axis, int):
+            axis = axis + a_ndim if axis < 0 else axis
+            assert a_shape[axis] == 1
+            axis = [axis]
+        else:
+            axis = [ele + a_ndim if ele < 0 else ele for ele in axis]
+            for ele in axis:
+                assert a_shape[ele] == 1
+    out_shape = []
+    search_axis = set(axis)
+    for i, a_dim in enumerate(a_shape):
+        if i not in search_axis:
+            out_shape.append(a_dim)
+    def _compute(*indices):
+        real_indices = []
+        flag = 0
+        for i in range(a_ndim):
+            if i not in search_axis:
+                real_indices.append(indices[i - flag])
+            else:
+                real_indices.append(0)
+                flag += 1
+        return a(*real_indices)
+
+    return tvm.compute(out_shape, _compute)
+
+
 @tvm.tag_scope(tag=tag.INJECTIVE)
 def concatenate(a_tuple, axis=0):
     """Join a sequence of arrays along an existing axis.

topi/tests/python/test_topi_transform.py

@@ -69,6 +69,28 @@ def verify_reshape(src_shape, dst_shape):
     check_device("metal")
 
 
+def verify_squeeze(src_shape, axis):
+    A = tvm.placeholder(shape=src_shape, name="A")
+    B = topi.squeeze(A, axis=axis)
+    s = topi.cuda.schedule_injective(B)
+    def check_device(device):
+        if not tvm.module.enabled(device):
+            print("Skip because %s is not enabled" % device)
+            return
+        ctx = tvm.gpu(0) if device == "cuda" else tvm.cl(0)
+        foo = tvm.build(s, [A, B], device, name="squeeze")
+        data_npy = np.random.normal(size=src_shape).astype(A.dtype)
+        out_npy = np.squeeze(data_npy, axis=axis)
+        data_nd = tvm.nd.array(data_npy, ctx)
+        out_nd = tvm.nd.empty(out_npy.shape, ctx=ctx, dtype=B.dtype)
+        foo(data_nd, out_nd)
+        np.testing.assert_allclose(out_nd.asnumpy(), out_npy)
+
+    check_device("cuda")
+    check_device("opencl")
+    check_device("metal")
+
+
 def verify_concatenate(shapes, axis):
     tensor_l = []
     for i, shape in enumerate(shapes):
@@ -133,6 +155,12 @@ def test_reshape():
     verify_reshape((16, ), (2, 2, 2, 2))
 
 
+def test_squeeze():
+    verify_squeeze((1, 2, 3, 4), 0)
+    verify_squeeze((1, 2, 1, 4), None)
+    verify_squeeze((1, 1, 1, 4), (1, 2))
+
+
 def test_concatenate():
     verify_concatenate([(2, 3, 4), (2, 2, 4), (2, 5, 4)], 1)
     verify_concatenate([(1, 2, 4), (1, 2, 3), (1, 2, 7), (1, 2, 8), (1, 2, 1)], -1)
@@ -152,6 +180,7 @@ if __name__ == "__main__":
     test_tranpose()
     test_expand_dims()
     test_reshape()
+    test_squeeze()
     test_concatenate()
     test_split()