ValueError: need at least one array to concatenate解决

如果传给np.vstack()的参数是一个空的列表或元组，就会抛出下面给出的错误信息。建议检查一下长度，大概率是空的。

Cell In[9], line 2, in plot_scores()
      1 def plot_scores():
----> 2     scores = np.vstack(ddpg_agents_tester.scores)
      3     scores = np.max(scores, 1)
      4     fig = plt.figure()

File <__array_function__ internals>:5, in vstack(*args, **kwargs)

File D:\Anaconda3\envs\DDPG\lib\site-packages\numpy\core\shape_base.py:283, in vstack(tup)
    281 if not isinstance(arrs, list):
    282     arrs = [arrs]
--> 283 return _nx.concatenate(arrs, 0)

File <__array_function__ internals>:5, in concatenate(*args, **kwargs)

ValueError: need at least one array to concatenate