b = torch.zeros((3, 2, 6, 6))
a = torch.zeros((3, 2, 1, 1))
a.expand_as(b).size()
Out[32]: torch.Size([3, 2, 6, 6])
a = torch.zeros((3, 2, 2, 1))
a.expand_as(b).size()
Traceback (most recent call last):
 File "/home/lart/.conda/envs/pt/lib/python3.6/site-packages/IPython/core/interactiveshell.py", line 3267, in run_code
  exec(code_obj, self.user_global_ns, self.user_ns)
 File "<ipython-input-34-972575f79e92>", line 1, in <module>
  a.expand_as(b).size()
RuntimeError: The expanded size of the tensor (6) must match the existing size (2) at non-singleton dimension 2. Target sizes: [3, 2, 6, 6]. Tensor sizes: [3, 2, 2, 1]
a = torch.zeros((3, 2, 1, 2))
a.expand_as(b).size()
Traceback (most recent call last):
 File "/home/lart/.conda/envs/pt/lib/python3.6/site-packages/IPython/core/interactiveshell.py", line 3267, in run_code
  exec(code_obj, self.user_global_ns, self.user_ns)
 File "<ipython-input-36-972575f79e92>", line 1, in <module>
  a.expand_as(b).size()
RuntimeError: The expanded size of the tensor (6) must match the existing size (2) at non-singleton dimension 3. Target sizes: [3, 2, 6, 6]. Tensor sizes: [3, 2, 1, 2]
a = torch.zeros((3, 2, 2, 2))
a.expand_as(b).size()
Traceback (most recent call last):
 File "/home/lart/.conda/envs/pt/lib/python3.6/site-packages/IPython/core/interactiveshell.py", line 3267, in run_code
  exec(code_obj, self.user_global_ns, self.user_ns)
 File "<ipython-input-38-972575f79e92>", line 1, in <module>
  a.expand_as(b).size()
RuntimeError: The expanded size of the tensor (6) must match the existing size (2) at non-singleton dimension 3. Target sizes: [3, 2, 6, 6]. Tensor sizes: [3, 2, 2, 2]
a = torch.zeros((3, 2, 6, 2))
a.expand_as(b).size()
Traceback (most recent call last):
 File "/home/lart/.conda/envs/pt/lib/python3.6/site-packages/IPython/core/interactiveshell.py", line 3267, in run_code
  exec(code_obj, self.user_global_ns, self.user_ns)
 File "<ipython-input-40-972575f79e92>", line 1, in <module>
  a.expand_as(b).size()
RuntimeError: The expanded size of the tensor (6) must match the existing size (2) at non-singleton dimension 3. Target sizes: [3, 2, 6, 6]. Tensor sizes: [3, 2, 6, 2]
a = torch.zeros((3, 2, 6, 1))
a.expand_as(b).size()
Out[44]: torch.Size([3, 2, 6, 6])
a = torch.zeros((3, 2, 1, 6))
a.expand_as(b).size()
Out[46]: torch.Size([3, 2, 6, 6])

tf.expand_dims(input, axis=None, name=None, dim=None)

# 't' is a tensor of shape [2]
shape(expand_dims(t, 0)) ==> [1, 2]
shape(expand_dims(t, 1)) ==> [2, 1]
shape(expand_dims(t, -1)) ==> [2, 1]
# 't2' is a tensor of shape [2, 3, 5]
shape(expand_dims(t2, 0)) ==> [1, 2, 3, 5]
shape(expand_dims(t2, 2)) ==> [2, 3, 1, 5]
shape(expand_dims(t2, 3)) ==> [2, 3, 5, 1]

tf.squeeze(input, axis=None, name=None, squeeze_dims=None)

# 't' is a tensor of shape [1, 2, 1, 3, 1, 1]
 shape(squeeze(t)) ==> [2, 3]
# 't' is a tensor of shape [1, 2, 1, 3, 1, 1]
 shape(squeeze(t, [2, 4])) ==> [1, 2, 3, 1]