开发笔记:Python基础之数据类型和运算——列表

作者：手机用户2602934713 | 来源：互联网 | 2023-10-13 03:42

篇首语：本文由编程笔记#小编为大家整理，主要介绍了Python基础之数据类型和运算——列表相关的知识，希望对你有一定的参考价值。

篇首语：本文由编程笔记#小编为大家整理，主要介绍了Python基础之数据类型和运算—— 列表相关的知识，希望对你有一定的参考价值。

列表

Python 有几个 复合数据类型，用于表示其它的值。最通用的是 list (列表) ，它可以写作中括号之间的一列逗号分隔的值。列表的元素不必是同一类型:

>>> squares = [1, 4, 9, 16, 25]
>>> squares
[1, 4, 9, 16, 25]

索引：

names = [‘Alex‘,"Tenglan",‘Eric‘]
>>> names[0]
‘Alex‘
>>> names[2]
‘Eric‘
>>> names[-1]
‘Eric‘
>>> names[-2] #还可以倒着取
‘Tenglan‘

切片：

print(name_list[1:4])#取下标1至下标4之间的值，包括1，不包括4

print(name_list[1:-1])#取下标1至下标-1的值，不包括-1（-1为最右边的值）
print(name_list[1:])#从1开始取直到最后一个，不能写-1，只能这么写
print(name_list[1:len(name_list)])#同上
print(name_list[0:3])#从头开始取，取3个值
print(name_list[:3])#如果是从头开始取，0可以忽略，跟上句效果一样
print(name_list[0::2])#后面的2表示每隔一个元素，取一个
print(name_list[::2])#效果同上
print(name_list[-3:-1])#从右边数第3个到最后一个，不包括最后第一个
print(name_list[-3:])#从右边数第3个到最后一个

所有的切片操作都会返回一个包含请求的元素的新列表。这意味着下面的切片操作返回列表一个新的（浅）拷贝副本:

print(name_list[:])

修改：

>>> names
[‘Alex‘, ‘Tenglan‘, ‘强行从Eric前面插入‘, ‘Eric‘, ‘Rain‘, ‘从eric后面插入试试新姿势‘, ‘Tom‘, ‘Amy‘, ‘我是新来的‘]
>>> names[2] = "该换人了"
>>> names
[‘Alex‘, ‘Tenglan‘, ‘该换人了‘, ‘Eric‘, ‘Rain‘, ‘从eric后面插入试试新姿势‘, ‘Tom‘, ‘Amy‘, ‘我是新来的‘]

也可以对切片赋值，此操作可以改变列表的尺寸，或清空它:

>>> letters = [‘a‘, ‘b‘, ‘c‘, ‘d‘, ‘e‘, ‘f‘, ‘g‘]
>>> letters
[‘a‘, ‘b‘, ‘c‘, ‘d‘, ‘e‘, ‘f‘, ‘g‘]
>>> # replace some values
>>> letters[2:5] = [‘C‘, ‘D‘, ‘E‘]
>>> letters
[‘a‘, ‘b‘, ‘C‘, ‘D‘, ‘E‘, ‘f‘, ‘g‘]
>>> # now remove them
>>> letters[2:5] = []
>>> letters
[‘a‘, ‘b‘, ‘f‘, ‘g‘]
>>> # clear the list by replacing all the elements with an empty list
>>> letters[:] = []
>>> letters
[]

追加：

>>> names
[‘Alex‘, ‘Tenglan‘, ‘Eric‘, ‘Rain‘, ‘Tom‘, ‘Amy‘]
>>> names.append("我是新来的")
>>> names
[‘Alex‘, ‘Tenglan‘, ‘Eric‘, ‘Rain‘, ‘Tom‘, ‘Amy‘, ‘我是新来的‘]

扩展：

>>> names
[‘Alex‘, ‘Tenglan‘, ‘Rain‘, ‘Tom‘, ‘Amy‘]
>>> b = [1,2,3]
>>> names.extend(b)
>>> names
[‘Alex‘, ‘Tenglan‘, ‘Rain‘, ‘Tom‘, ‘Amy‘, 1, 2, 3]

列表也支持连接这样的操作:

>>> squares + [36, 49, 64, 81, 100]
[1, 4, 9, 16, 25, 36, 49, 64, 81, 100]

插入：

>>> names
[‘Alex‘, ‘Tenglan‘, ‘Eric‘, ‘Rain‘, ‘Tom‘, ‘Amy‘, ‘我是新来的‘]
>>> names.insert(2,"强行从Eric前面插入")
>>> names
[‘Alex‘, ‘Tenglan‘, ‘强行从Eric前面插入‘, ‘Eric‘, ‘Rain‘, ‘Tom‘, ‘Amy‘, ‘我是新来的‘]
>>> names.insert(5,"从eric后面插入试试新姿势")
>>> names
[‘Alex‘, ‘Tenglan‘, ‘强行从Eric前面插入‘, ‘Eric‘, ‘Rain‘, ‘从eric后面插入试试新姿势‘, ‘Tom‘, ‘Amy‘, ‘我是新来的‘]

删除：

>>> del names[2]
>>> names
[‘Alex‘, ‘Tenglan‘, ‘Eric‘, ‘Rain‘, ‘从eric后面插入试试新姿势‘, ‘Tom‘, ‘Amy‘, ‘我是新来的‘]
>>> del names[4]
>>> names
[‘Alex‘, ‘Tenglan‘, ‘Eric‘, ‘Rain‘, ‘Tom‘, ‘Amy‘, ‘我是新来的‘]
>>>
>>> names.remove("Eric") #删除指定元素，只能删一个
>>> names
[‘Alex‘, ‘Tenglan‘, ‘Rain‘, ‘Tom‘, ‘Amy‘, ‘我是新来的‘]
>>> names.pop() #删除列表最后一个值
‘我是新来的‘
>>> names
[‘Alex‘, ‘Tenglan‘, ‘Rain‘, ‘Tom‘, ‘Amy‘]

拷贝：

>>> names
[‘Alex‘, ‘Tenglan‘, ‘Rain‘, ‘Tom‘, ‘Amy‘, 1, 2, 3]
>>> name_copy = names.copy()
>>> name_copy
[‘Alex‘, ‘Tenglan‘, ‘Rain‘, ‘Tom‘, ‘Amy‘, 1, 2, 3]

此处的copy只能浅拷贝，即只能拷贝一层，例如：

>>> text = [‘a‘,‘b‘,‘c‘,‘d‘,[‘A‘,‘B‘,‘C‘],‘e‘,‘f‘]>>> text_copy = text.copy()
>>> text_copy
[‘a‘, ‘b‘, ‘c‘, ‘d‘, [‘A‘, ‘B‘, ‘C‘], ‘e‘, ‘f‘]
>>> text[4][1] = ‘ZZZ‘
>>> text
[‘a‘, ‘b‘, ‘c‘, ‘d‘, [‘A‘, ‘ZZZ‘, ‘C‘], ‘e‘, ‘f‘]
>>> text_copy #并没有修改text_copy的内容，但是却被更改。证明这个copy 是浅拷贝
[‘a‘, ‘b‘, ‘c‘, ‘d‘, [‘A‘, ‘ZZZ‘, ‘C‘], ‘e‘, ‘f‘]

在列表嵌套列表的存储中，实际存的是子列表的指针，浅拷贝拷贝的也是相应子列表指针，所以更改子列表元素原列表和复制列表都会改变。

>>> text_copy[4][0] = ‘Yang‘
>>> text
[‘a‘, ‘b‘, ‘c‘, ‘d‘, [‘Yang‘, ‘ZZZ‘, ‘C‘], ‘e‘, ‘f‘]
>>> text_copy
[‘a‘, ‘b‘, ‘c‘, ‘d‘, [‘Yang‘, ‘ZZZ‘, ‘C‘], ‘e‘, ‘f‘]

深层拷贝：

import copy #拷贝模块
text = [‘a‘,‘b‘,‘c‘,‘d‘,[‘A‘,‘B‘,‘C‘],‘e‘,‘f‘]
print(" text=",text)
text_copy = copy.deepcopy(text) #深层拷贝
print("text_copy=",text_copy)
text[4][1] = "ZZZ"
print("Chang text: text=",text)
print("Chang text: text_copy=",text_copy)
text_copy[4][0] = "Yang"
print("Chang text_copy: text=",text)
print("Chang text_copy: text_copy=",text_copy)
输出：
text= [‘a‘, ‘b‘, ‘c‘, ‘d‘, [‘A‘, ‘B‘, ‘C‘], ‘e‘, ‘f‘]
text_copy= [‘a‘, ‘b‘, ‘c‘, ‘d‘, [‘A‘, ‘B‘, ‘C‘], ‘e‘, ‘f‘]
Chang text: text= [‘a‘, ‘b‘, ‘c‘, ‘d‘, [‘A‘, ‘ZZZ‘, ‘C‘], ‘e‘, ‘f‘]
Chang text: text_copy= [‘a‘, ‘b‘, ‘c‘, ‘d‘, [‘A‘, ‘B‘, ‘C‘], ‘e‘, ‘f‘]
Chang text_copy: text= [‘a‘, ‘b‘, ‘c‘, ‘d‘, [‘A‘, ‘ZZZ‘, ‘C‘], ‘e‘, ‘f‘]
Chang text_copy: text_copy= [‘a‘, ‘b‘, ‘c‘, ‘d‘, [‘Yang‘, ‘B‘, ‘C‘], ‘e‘, ‘f‘]

深拷贝是完全拷贝，子列表也重新保存。

浅拷贝三种：

p1 = copy.copy(person)
p2 = person[:]
p3 = list(person)

统计：

>>> names
[‘Alex‘, ‘Tenglan‘, ‘Amy‘, ‘Tom‘, ‘Amy‘, 1, 2, 3]
>>> names.count("Amy")
2

排序&翻转：

>>> names
[‘Alex‘, ‘Tenglan‘, ‘Amy‘, ‘Tom‘, ‘Amy‘, 1, 2, 3]
>>> names.sort() #排序
Traceback (most recent call last):
File "", line 1, in
TypeError: unorderable types: int() #3.0里不同数据类型不能放在一起排序了，擦
>>> names[-3] = ‘1‘
>>> names[-2] = ‘2‘
>>> names[-1] = ‘3‘
>>> names
[‘Alex‘, ‘Amy‘, ‘Amy‘, ‘Tenglan‘, ‘Tom‘, ‘1‘, ‘2‘, ‘3‘]
>>> names.sort()
>>> names
[‘1‘, ‘2‘, ‘3‘, ‘Alex‘, ‘Amy‘, ‘Amy‘, ‘Tenglan‘, ‘Tom‘]
>>> names.reverse() #反转
>>> names
[‘Tom‘, ‘Tenglan‘, ‘Amy‘, ‘Amy‘, ‘Alex‘, ‘3‘, ‘2‘, ‘1‘]

获取下标：

>>> names
[‘Tom‘, ‘Tenglan‘, ‘Amy‘, ‘Amy‘, ‘Alex‘, ‘3‘, ‘2‘, ‘1‘]
>>> names.index("Amy")
2 #只返回找到的第一个下标

class list(object):
"""
list() -> new empty list
list(iterable) -> new list initialized from iterable‘s items
"""
def append(self, p_object): # real signature unknown; restored from __doc__
""" L.append(object) -- append object to end """
pass
def count(self, value): # real signature unknown; restored from __doc__
""" L.count(value) -> integer -- return number of occurrences of value """
return 0
def extend(self, iterable): # real signature unknown; restored from __doc__
""" L.extend(iterable) -- extend list by appending elements from the iterable """
pass
def index(self, value, start=None, stop=None): # real signature unknown; restored from __doc__
"""
L.index(value, [start, [stop]]) -> integer -- return first index of value.
Raises ValueError if the value is not present.
"""
return 0
def insert(self, index, p_object): # real signature unknown; restored from __doc__
""" L.insert(index, object) -- insert object before index """
pass
def pop(self, index=None): # real signature unknown; restored from __doc__
"""
L.pop([index]) -> item -- remove and return item at index (default last).
Raises IndexError if list is empty or index is out of range.
"""
pass
def remove(self, value): # real signature unknown; restored from __doc__
"""
L.remove(value) -- remove first occurrence of value.
Raises ValueError if the value is not present.
"""
pass
def reverse(self): # real signature unknown; restored from __doc__
""" L.reverse() -- reverse *IN PLACE* """
pass
def sort(self, cmp=None, key=None, reverse=False): # real signature unknown; restored from __doc__
"""
L.sort(cmp=None, key=None, reverse=False) -- stable sort *IN PLACE*;
cmp(x, y) -> -1, 0, 1
"""
pass
def __add__(self, y): # real signature unknown; restored from __doc__
""" x.__add__(y) <==> x+y """
pass
def __contains__(self, y): # real signature unknown; restored from __doc__
""" x.__contains__(y) <==> y in x """
pass
def __delitem__(self, y): # real signature unknown; restored from __doc__
""" x.__delitem__(y) <==> del x[y] """
pass
def __delslice__(self, i, j): # real signature unknown; restored from __doc__
"""
x.__delslice__(i, j) <==> del x[i:j]

Use of negative indices is not supported.
"""
pass
def __eq__(self, y): # real signature unknown; restored from __doc__
""" x.__eq__(y) <==> x==y """
pass
def __getattribute__(self, name): # real signature unknown; restored from __doc__
""" x.__getattribute__(‘name‘) <==> x.name """
pass
def __getitem__(self, y): # real signature unknown; restored from __doc__
""" x.__getitem__(y) <==> x[y] """
pass
def __getslice__(self, i, j): # real signature unknown; restored from __doc__
"""
x.__getslice__(i, j) <==> x[i:j]

Use of negative indices is not supported.
"""
pass
def __ge__(self, y): # real signature unknown; restored from __doc__
""" x.__ge__(y) <==> x>=y """
pass
def __gt__(self, y): # real signature unknown; restored from __doc__
""" x.__gt__(y) <==> x>y """
pass
def __iadd__(self, y): # real signature unknown; restored from __doc__
""" x.__iadd__(y) <==> x+=y """
pass
def __imul__(self, y): # real signature unknown; restored from __doc__
""" x.__imul__(y) <==> x*=y """
pass
def __init__(self, seq=()): # known special case of list.__init__
"""
list() -> new empty list
list(iterable) -> new list initialized from iterable‘s items
# (copied from class doc)
"""
pass
def __iter__(self): # real signature unknown; restored from __doc__
""" x.__iter__() <==> iter(x) """
pass
def __len__(self): # real signature unknown; restored from __doc__
""" x.__len__() <==> len(x) """
pass
def __le__(self, y): # real signature unknown; restored from __doc__
""" x.__le__(y) <==> x<=y """
pass
def __lt__(self, y): # real signature unknown; restored from __doc__
""" x.__lt__(y) <==> x"""
pass
def __mul__(self, n): # real signature unknown; restored from __doc__
""" x.__mul__(n) <==> x*n """
pass
@staticmethod # known case of __new__
def __new__(S, *more): # real signature unknown; restored from __doc__
""" T.__new__(S, ...) -> a new object with type S, a subtype of T """
pass
def __ne__(self, y): # real signature unknown; restored from __doc__
""" x.__ne__(y) <==> x!=y """
pass
def __repr__(self): # real signature unknown; restored from __doc__
""" x.__repr__() <==> repr(x) """
pass
def __reversed__(self): # real signature unknown; restored from __doc__
""" L.__reversed__() -- return a reverse iterator over the list """
pass
def __rmul__(self, n): # real signature unknown; restored from __doc__
""" x.__rmul__(n) <==> n*x """
pass
def __setitem__(self, i, y): # real signature unknown; restored from __doc__
""" x.__setitem__(i, y) <==> x[i]=y """
pass
def __setslice__(self, i, j, y): # real signature unknown; restored from __doc__
"""
x.__setslice__(i, j, y) <==> x[i:j]=y

Use of negative indices is not supported.
"""
pass
def __sizeof__(self): # real signature unknown; restored from __doc__
""" L.__sizeof__() -- size of L in memory, in bytes """
pass
__hash__ = None
list

功能源码

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