输入(x) 是一个形状为[2, 3, 1]的 3-D Tensor :

        [
           [[1], [2], [3]],
           [[4], [5], [6]]
        ]

target_tensor的维度 :  [2, 6, 2]

输出(out) 是一个形状为[2, 6, 2]的 3-D Tensor:

        [
            [[1, 1], [2, 2], [3, 3], [1, 1], [2, 2], [3, 3]],
            [[4, 4], [5, 5], [6, 6], [4, 4], [5, 5], [6, 6]]
        ]

import paddle.fluid as fluid
import numpy as np
data = fluid.data(name="data", shape=[-1,10], dtype='float64')
target_tensor = fluid.data(name="target_tensor", shape=[-1,20], dtype='float64')
result = fluid.layers.expand_as(x=data, target_tensor=target_tensor)
use_cuda = False
place = fluid.CUDAPlace(0) if use_cuda else fluid.CPUPlace()
exe = fluid.Executor(place)
exe.run(fluid.default_startup_program())
x = np.random.rand(3,10)
y = np.random.rand(3,20)
output= exe.run(feed={"data":x,"target_tensor":y},fetch_list=[result.name])
print(output[0].shape)
#(3,20)