Lists to numpy array

问题

Why does the following code generate a numpy array with lists printed inside the array for list3?

enter image description here Output observed:

list2=[[1,2,3],[4,5,6],[7,8,9]] #list of 3 lists makes 3 rows and 3 
columns for numpy array
#each list fills one row
print('List2',list2)
print('List2 casted as 3x3 array',np.array(list2))

list3=[[1,2,3],[4,5,6],[7,8]]
print(np.array(list3))

来源：https://stackoverflow.com/questions/56455371/lists-to-numpy-array