Data Examples

Lists in Environment Diagrams

注意：切片 or addition 是引用，而不是复制，有时候可能不经意改变

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>>> t = [1,2,3]
>>> t[1:3] = [t]
>>> t.extend(t)
>>> print(t)
[1, [...], 1, [...]]

在Python中，当你尝试打印一个包含自身的列表时，列表无法递归地打印出所有的元素，因为它会无限循环地引用自己。为了避免这种无限循环，Python会用[…]来表示列表中被省略的部分。

Obj Systems in Python

• return a string -> 'str', print a string -> str

• .some_attr: can create a new attribute for the instance at once, or get the value of an existing attribute

Iterators and Iterables in Python

training test

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def digit_dict(s):
    """
    >>> digit_dict([5, 2, 13])
    {2: [2], 3: [13], 5: [5]}
    """
    last_digit = [x % 10 for x in s]
    return {d: [x for x in s if x % 10 == d] for d in range(10) if d in last_digit}

.count() method:

• <built-in method count of list object at 0x000001>
• [1 for x in range(10) if ...] 计数