简单赋值不会复制对象或其数据。

>>> a = np.array([[ 0,  1,  2,  3],
...               [ 4,  5,  6,  7],
...               [ 8,  9, 10, 11]])
>>> b = a            # no new object is created
>>> b is a           # a and b are two names for the same ndarray object
True

Python 将可变对象作为引用传递，因此函数调用不会进行复制。

>>> def f(x):
...     print(id(x))
...
>>> id(a)  # id is a unique identifier of an object
148293216  # may vary
>>> f(a)
148293216  # may vary