python curd增删改查

增

append 增加

In [1]: hero = ['1','2']

In [2]: hero.append('3')

In [3]: hero
Out[3]: ['1', '2', '3']

extend 多个增加

In [3]: hero
Out[3]: ['1', '2', '3']

In [4]: hero.extend(['4','5','6'])

In [5]: hero
Out[5]: ['1', '2', '3', '4', '5', '6']

len(s): 通过长度增加

In [6]: s = [1, 2, 3, 4, 5]

In [7]: s[len(s):] = [6]

In [8]: s
Out[8]: [1, 2, 3, 4, 5, 6]

In [9]: s[len(s):] = [7,8,9]

In [10]: s
Out[10]: [1, 2, 3, 4, 5, 6, 7, 8, 9]

insert 增加对应的元素（在1的后面加上逗号后面的2）

In [11]: s = [1,3,4,5]

In [12]: s.insert(1,2)

In [13]: s
Out[13]: [1, 2, 3, 4, 5]

删

remove 删除指定元素

In [5]: hero
Out[5]: ['1', '2', '3', '4', '5', '6']

In [14]: hero.remove('1')

In [15]: hero
Out[15]: ['2', '3', '4', '5', '6']

pop 删除下标对应元素

In [17]: hero
Out[17]: ['2', '3', '4', '5', '6']

In [18]: hero.pop(2)
Out[18]: '4'

In [19]: hero
Out[19]: ['2', '3', '5', '6']

clear 清空

In [19]: hero
Out[19]: ['2', '3', '5', '6']

In [20]: hero.clear()

In [21]: hero
Out[21]: []

改

[ ] = " " 替换

In [22]: hero = ['1','2','3','4','5','6']

In [23]: hero[4] = "55"

In [24]: hero
Out[24]: ['1', '2', '3', '4', '55', '6']

[ :] = " " 批量替换

In [24]: hero
Out[24]: ['1', '2', '3', '4', '55', '6']

In [25]: hero [3:] = ['44','55','66']

In [26]: hero
Out[26]: ['1', '2', '3', '44', '55', '66']

sort 正序排序

In [27]: nums = [3,1,9,6,8,3,5,3]

In [28]: nums.sort()

In [29]: nums
Out[29]: [1, 3, 3, 3, 5, 6, 8, 9]

reverse 倒叙排序

In [29]: nums
Out[29]: [1, 3, 3, 3, 5, 6, 8, 9]

In [30]: nums.reverse()

In [31]: nums
Out[31]: [9, 8, 6, 5, 3, 3, 3, 1]


In [33]: nums.sort(reverse=True)

In [34]: nums
Out[34]: [9, 8, 6, 5, 3, 3, 3, 1]

copy 复制数组(浅拷贝)

In [47]: nums
Out[47]: [3, 1, 9, 6, 8, 3, 5, 3]

In [48]: nums_copy1 = nums.copy()

In [49]: nums_copy1
Out[49]: [3, 1, 9, 6, 8, 3, 5, 3]

copy 用切片来指定所有，效果是一样的(浅拷贝)

In [49]: nums_copy1
Out[49]: [3, 1, 9, 6, 8, 3, 5, 3]

In [50]: nums_copy2 = nums[:]

In [51]: nums_copy2
Out[51]: [3, 1, 9, 6, 8, 3, 5, 3]

查

count 查找目标元素出现次数

In [34]: nums
Out[34]: [9, 8, 6, 5, 3, 3, 3, 1]

In [35]: nums.count(3)
Out[35]: 3

index 查找目标元素的索引值

In [37]: heros = ['riven','yasuo','zark','nadalee','leesin','draven']

In [38]: heros.index("leesin")
Out[38]: 4

通过index查询更改(这里leesin就是=4)

In [39]: heros
Out[39]: ['riven', 'yasuo', 'zark', 'nadalee', 'leesin', 'draven']

In [40]: heros[heros.index("leesin")] = "ashe"

In [41]: heros
Out[41]: ['riven', 'yasuo', 'zark', 'nadalee', 'ashe', 'draven']

通过index查询目标的第一个索引值是多少

In [43]: nums = [3,1,9,6,8,3,5,3]

In [44]: nums.index(3)
Out[44]: 0

通过index查询目标的第一个索引值是多少(指定范围)

In [45]: nums
Out[45]: [3, 1, 9, 6, 8, 3, 5, 3]

In [46]: nums.index(3,1,7)
Out[46]: 5