python序列(列表，元组，字典)的增删改查

增加元素到末尾

>>> list1=[‘hello‘,‘world‘,‘how‘,‘are‘,‘you‘]

>>> list1.append(‘!‘)

>>> list1

[‘hello‘, ‘world‘, ‘how‘, ‘are‘, ‘you‘, ‘!‘]

增加元素到指定位置

index:索引位置

obj：内容

>>> list1

[‘hello‘, ‘world‘, ‘how‘, ‘are‘, ‘you‘, ‘!‘]

>>> list1.insert(1,‘,‘)

>>> list1

[‘hello‘, ‘,‘, ‘world‘, ‘how‘, ‘are‘, ‘you‘, ‘!‘]

将list_i列表中的元素增加到list中

>>> list

[‘hello‘, ‘how‘, ‘are‘, ‘you‘]

>>> list.extend([‘good‘,‘girl‘])

>>> list

[‘hello‘, ‘how‘, ‘are‘, ‘you‘, ‘good‘, ‘girl‘]

默认删除list末尾的元素

list.pop(index)

删除指定位置的元素,index是索引

>>> list1

[‘hello‘, ‘,‘, ‘world‘, ‘how‘, ‘are‘, ‘you‘, ‘!‘]

>>> list1.pop()

‘!‘

>>> list1.pop(1)

‘,‘

删除指定位置的元素，index是索引

del list

删除整个列表

>>> list1

[‘hello‘, ‘world‘, ‘how‘, ‘are‘, ‘you‘]

>>> del list1[1]

>>> list1

[‘hello‘, ‘how‘, ‘are‘, ‘you‘]

>>> list1

[‘hello‘, ‘how‘, ‘are‘, ‘you‘]

>>> del list1

>>> list1

Traceback (most recent call last):

File "<stdin>", line
1, in <module>

NameError: name ‘list1‘ is not defined

移除列表第一个与obj相等的元素

>>> list=[‘hello‘, ‘world‘, ‘how‘, ‘are‘, ‘you‘]

>>> list.remove(‘world‘)

>>> list

[‘hello‘, ‘how‘, ‘are‘, ‘you‘]

清空列表全部内容

>>> list=[‘hello‘, ‘world‘, ‘how‘, ‘are‘, ‘you‘]

>>> list.clear()

>>> list

[]

修改指定位置的元素

>>> list1

[‘hello‘, ‘world‘, ‘how‘, ‘are‘, ‘you‘]

>>> list1[0]=‘hi‘

>>> list1

[‘hi‘, ‘world‘, ‘how‘, ‘are‘, ‘you‘]

通过下标索引，从0开始

>>> list=[‘hello‘, ‘world‘, ‘how‘, ‘are‘, ‘you‘]

>>> list[2]

‘how‘

切片,顾头不顾尾

>>> list=[‘hello‘, ‘world‘, ‘how‘, ‘are‘, ‘you‘]

>>> list[0:3]

[‘hello‘, ‘world‘, ‘how‘]

>>> list[1:]

[‘world‘, ‘how‘, ‘are‘, ‘you‘]

>>> list[:3]

[‘hello‘, ‘world‘, ‘how‘]

>>> list[:]

[‘hello‘, ‘world‘, ‘how‘, ‘are‘, ‘you‘]

元组不支持修改，但可以通过连接组合的方式进行增加

>>> tup1=(1,2,3)

>>> tup2=(4,5,6)

>>> tup=tup1+tup2

>>> tup

(1, 2, 3, 4, 5, 6)

元组不支持单个元素删除，但可以删除整个元组

>>> tup

(1, 2, 3, 4, 5, 6)

>>> del tup

>>> tup

Traceback (most recent call last):

File "<stdin>", line
1, in <module>

NameError: name ‘tup‘ is not defined

tup=tup[index1:index2]

元组是不可变类型，不能修改元组的元素。可通过现有的字符串拼接构造一个新元组

>>> tup=(‘a‘,‘b‘,‘c‘,‘d‘,‘e‘)

>>> tup=tup[1],tup[2],tup[4]

>>> tup

(‘b‘, ‘c‘, ‘e‘)

>>> tup=(‘a‘,‘b‘,‘c‘,‘d‘,‘e‘)

>>> tup=tup[1:3]

>>> tup

(‘b‘, ‘c‘)

通过下标索引，从0开始

>>> tup=(1,2,3,4)

>>> tup[2]

3

切片,顾头不顾尾

>>> tup=(1,2,3,4)

>>> tup[1:3]

(2, 3)

>>> tup[1:]

(2, 3, 4)

>>> tup[:3]

(1, 2, 3)

>>> tup[:]

(1, 2, 3, 4)

通过赋值的方法增加元素

>>> dict={‘name‘:‘li‘,‘age‘:1}

>>> dict[‘class‘]=‘first‘

>>> dict

{‘name‘: ‘li‘, ‘age‘: 1, ‘class‘: ‘first‘}

把新的字典dict_i的键/值对更新到dict里(适用dict_i中包含与dict不同的key)

>>> dict={‘name‘: ‘li‘, ‘age‘: 1, ‘class‘: ‘first‘}

>>> dict.update(school=‘wawo‘)

>>> dict

{‘name‘: ‘li‘, ‘age‘: 1, ‘class‘: ‘first‘, ‘school‘: ‘wawo‘}

删除单一元素，通过key来指定删除

del dict

删除字典

>>> dict

{‘name‘: ‘li‘, ‘age‘: 1, ‘class‘: ‘first‘}

>>> del dict[‘class‘]

>>> dict

{‘name‘: ‘li‘, ‘age‘: 1}

>>> dict1={‘name‘: ‘li‘, ‘age‘: 1, ‘class‘: ‘first‘}

>>> del dict1

>>> dict1

Traceback (most recent call last):

File "<stdin>", line
1, in <module>

NameError: name ‘dict1‘ is not defined

删除单一元素，通过key来指定删除

>>> dict={‘name‘: ‘li‘, ‘age‘: 1, ‘class‘: ‘first‘}

>>> dict.pop(‘name‘)

‘li‘

>>> dict

{‘age‘: 1, ‘class‘: ‘first‘}

清空全部内容

>>> dict

{‘age‘: 1, ‘class‘: ‘first‘}

>>> dict.clear()

>>> dict

{}

通过对已有的key重新赋值的方法修改

>>> dict

{‘name‘: ‘pang‘, ‘age‘: 1, ‘class‘: ‘first‘, ‘school‘: ‘wawo‘}

>>> dict[‘name‘]=‘li‘

>>> dict

{‘name‘: ‘li‘, ‘age‘: 1, ‘class‘: ‘first‘, ‘school‘: ‘wawo‘}

把字典dict_i的键/值对更新到dict里(适用dict_i中包含与dict相同的key)

>>> dict

{‘name‘: ‘li‘, ‘age‘: 1, ‘class‘: ‘first‘, ‘school‘: ‘wawo‘}

>>> dict.update(name=‘pang‘)

>>> dict

{‘name‘: ‘pang‘, ‘age‘: 1, ‘class‘: ‘first‘, ‘school‘: ‘wawo‘}

通过key访问value值

>>> dict={‘name‘: ‘pang‘, ‘age‘: 1, ‘class‘: ‘first‘, ‘school‘:
‘wawo‘}

>>> dict[‘name‘]

‘pang‘

以列表返回可遍历的(键, 值) 元组数组

>>> dict={‘name‘: ‘pang‘, ‘age‘: 1, ‘class‘: ‘first‘, ‘school‘:
‘wawo‘}

>>> dict.items()

dict_items([(‘name‘, ‘pang‘), (‘age‘, 1), (‘class‘, ‘first‘), (‘school‘,
‘wawo‘)])

以列表返回一个字典所有键值

dict.values()

以列表返回一个字典所有值

>>> dict.keys()

dict_keys([‘name‘, ‘age‘, ‘class‘, ‘school‘])

>>> dict.values()

dict_values([‘pang‘, 1, ‘first‘, ‘wawo‘])

返回指定key的对应字典值，没有返回none

>>> dict.get(‘age‘)

1