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  • python day2学习整理

    python学习的第二天

    今天一天的知识点很多，详细介绍了python 字符串，列表，元祖，字典，集合等的方法。抛砖引玉...   name = 'alex' ###那么name就是str类的对象                                                                                      

    1.字符串

    1.1 capitalize

    字符串首字母大写，自身不变，会生成一个新的值。

    1 #/usr/bin/python
2 
3 new_name = name.capitalize()
4 print(new_name)
5 print(name)

    1.2 casefold

    将所有大写变小写，包括德语等等...

    1 #/usr/bin/python
2 name = 'Alex'
3 name_new = name.casefold()
4 print(name_new)
5 print(name)

    1.3 lower

    将所有大小写变小写

    1 #/usr/bin/python
2 name = 'ALEx'
3 new_name = name.lower()
4 print(name)
5 print(new_name)

    1.4 center

    文本居中，参数1表示总长度，参数2表示空白处填充的字符(长度为1)

    #/usr/bin/python
name = 'alex'
new_name = name.center(20,'*')
print(new_name)

    1.5 count

    表示传入值在字符串中出现的次数

    参数1：要查找的值(子序列)

    参数2：起始位置(索引)

    参数3: 结束位置(索引)

    #/usr/bin/python
name = 'alexbsefsdfwefsadsf'
v = name.count(a)
d = name.count(1,7)
print(v)
print(d)

    1.6 startswith endswith

    是否已xx开头,是否已xx结束

    #/usr/bin/python
name = 'alex'
print(name.startswith('al'))
print(name.startswith('ex'))

    1.7 expandtabs

    找到制表符 ，进行替换，包含前面的值

    1 #/usr/bin/python
2 name = 'alex/tbb/tcc/tkkk'
3 v = name.expandtabs(20)
4 print(v)

    1.8 find index

    找到指定子序列的索引位置，不存在返回-1

    1 #/usr/bin/python
2 name = 'alex'
3 v = name.find('0')
4 print(v)
5 v = name.index('0')
6 print(v)

    1.9 字符串输出格式化

    #/usr/bin/python

tpl = "我是:%s;年龄:%s;性别:%s"

tpl = "我是:{0};年龄:{1};性别:{2}"
v = tpl.format("李杰",19,'都行')
print(v)

tpl = "我是:{name};年龄:{age};性别:{gender}"
v = tpl.format(name='李杰',age=19,gender='随意')
print(v)
 tpl = "我是:{name};年龄:{age};性别:{gender}"
v = tpl.format_map({'name':"李杰",'age':19,'gender':'中'})
print(v)

    1.10 是否是数字

    1 #/usr/bin/python
2  num = '②'
3  v1 = num.isdecimal() # '123'
4  v2 = num.isdigit()   # '123'，'②'
5  v3 = num.isnumeric() # '123'，'二'，'②'
6  print(v1,v2,v3)

    1.11 是否是表示符

    1 #/usr/bin/python
2  n = 'name'
3  v = n.isidentifier()
4  print(v)

    1.12 是否全部是大小写

    1 #/usr/bin/python
2  name = "ALEX"
3  v = name.islower()
4  print(v)
5  v = name.isupper()
6  print(v)

    1.13 全部变大写

    #/usr/bin/python
 name = 'alex'
 v = name.upper()  # lower()
 print(v)

    1.14 是否包含隐藏的xx

    #/usr/bin/python
 name = "钓鱼要钓刀鱼，
刀鱼要到岛上钓"
 v = name.isprintable()
 print(v)

    1.15 是否全部是空格

    1 #/usr/bin/python
2  name = '    '
3  v = name.isspace()
4  print(v)

    1.16 元素拼接

     1 #/usr/bin/python
 2 
 3  name = 'alex'
 4 
 5  v = "_".join(name) # 内部循环每个元素
 6  print(v)
 7 
 8  name_list = ['海峰','杠娘','李杰','李泉']
 9  v = "搞".join(name_list)
10  print(v)

    1.17 左右填充数据（ljust，rjust）

    1 #/usr/bin/python
2  name = 'alex'
3  v = name.rjust(20,'*')
4  print(v)

    1.18 maketrans + translate

    1 #/usr/bin/python
2 # m = str.maketrans('aeiou','12345') # 对应关系
3 #
4 # name = "akpsojfasdufasdlkfj8ausdfakjsdfl;kjer09asdf"
5 # v = name.translate(m)
6 # print(v)

    1.19 partition

    分割，元素保留

    1 #/usr/bin/python
2 # content = "李泉SB刘康SB刘一"
3 # v = content.partition('SB') # partition
4 # print(v)

    1.20 replace 替换

    1 #/usr/bin/python
2 # content = "李泉SB刘康SB刘浩SB刘一"
3 # v = content.replace('SB','Love')
4 # print(v)
5 # v = content.replace('SB','Love',1)
6 # print(v)

    1.21 strip

    移除空白，自定义 

    1 #/usr/bin/python
2 # name = 'alex	'
3 # v = name.strip() # 空白,
,	
4 # print(v)

    1.22 swapcase

    大小写转化

    1 #/usr/bin/python
2 # name = "Alex"
3 # v = name.swapcase()
4 # print(v)

    1.23 zfill

    填充0

     1 #/usr/bin/python
 2 # name = "alex"
 3 # v = name.zfill(20)
 4 # print(v)
 5 
 6 # v1 = 'alex'
 7 # v2 = 'eric'
 8 #
 9 # v = v1 + v2 # 执行v1的__add__功能
10 # print(v)

    1.24 常用字符串功能总结和额外功能

     1 #/usr/bin/python
 2 常用功能：
 3 # name = 'alex'
 4 # name.upper()
 5 # name.lower()
 6 # name.split()
 7 # name.find()
 8 # name.strip()
 9 # name.startswith()
10 # name.format()
11 # name.replace()
12 # "alex".join(["aa",'bb'])
13 
14 
15 额外功能：
16 # name = "alex"
17 # name[0]
18 # name[0:3]
19 # name[0:3:2]
20 # len(name)
21 # for循环，每个元素是字符

    2 int 整数

    2.1 bit_length

    当前整数的二进制表示，最少位数

     1 #/usr/bin/python

    2 # age = 4 # 100

    3 # print(age.bit_length()) 

    2.2 to_bytes

    获取当前数据的字节表示

    1 #/usr/bin/python
2 # age = 15
3 # v = age.to_bytes(10,byteorder='big')
4 # v = age.to_bytes(10,byteorder='little')
5 # print(v)
6 # 00000000 00001111 -> 15

    3 bool 布尔值

    v = 0 # 1,-1
    v = ""
    v = []
    --> 空内容：False

    4 list 列表

    list 列表是可变类型

    4.1 append

    追加

    1 #/usr/bin/python
2  user_list = ['李白','刘禹锡','刘一番','杜甫,'小小萝莉'] # 可变类型
3  user_list.append('刘章')
4  print(user_list)

    4.2 clear

    清空

    #/usr/bin/python 
user_list = ['李白','刘禹锡','刘一番','杜甫,'小小萝莉'] # 可变类型
user_list.clear()
print(user_list)

    4.3 copy

    拷贝，浅拷贝

    1 #/usr/bin/python
2  user_list = ['李白','刘禹锡','刘一番','杜甫,'小小萝莉'] # 可变类型
3  v = user_list.copy()
4  print(user_list)
5  print(v)

    4.3 count

    计数

    #/usr/bin/python
 user_list = ['李白','刘禹锡','刘一番','杜甫,'小小萝莉'] # 可变类型
 v= user_list.count('李白')
 print(v)
 print(user_list)

    4.4 extend

    扩展原列表

    #/usr/bin/python
 user_list = ['李白','刘禹锡','刘一番','杜甫,'小小萝莉'] # 可变类型
 user_list.extent('李白酒'，'杜康')
 print(user_list)

    4.5 index

    查找元素索引，没有就报错

    #/usr/bin/python
 user_list = ['李白','刘禹锡','刘一番','杜甫,'小小萝莉'] # 可变类型
 v= user_list.index('李白')
 print(v)
 print(user_list)

    4.6 pop

    获取并且删除元素，根据索引

    1 #/usr/bin/python
2  user_list = ['李白','刘禹锡','刘一番','杜甫,'小小萝莉'] # 可变类型
3  v= user_list.pop(3)
4  print(v)
5  print(user_list)

    4.7 remove

    删除元素，根据值

    #/usr/bin/python
 user_list = ['李白','刘禹锡','刘一番','杜甫,'小小萝莉'] # 可变类型
 v= user_list.remove('李白')
 print(v)
 print(user_list)

    4.8 reverse

    翻转

    1 #/usr/bin/python
2  user_list = ['李白','刘禹锡','刘一番','杜甫,'小小萝莉'] # 可变类型
3  user_list.reverse()
4  print(user_list)

    4.9 sort

    1 #/usr/bin/python
2 # nums = [11,22,3,3,9,88]
3 # print(nums)
4 # 排序，从小到大
5 # nums.sort()
6 # print(nums)
7 # 从大到小
8 # nums.sort(reverse=True)
9 # print(nums)

    4.10 额外功能

     1 #/usr/bin/python
 2 # user_list = ['李泉','刘一','李泉','刘康','豆豆','小龙']
 3 # user_list[0]
 4 # user_list[1:5:2]
 5 # del user_list[3]
 6 # for i in user_list:
 7 #     print(i)
 8 # user_list[1] = '姜日天'
 9 # user_list = ['李泉','刘一','李泉','刘康','豆豆',['日天','日地','泰迪'],'小龙']
10 
11 
12 # li = ['eric','alex','tony']
13 #
14 # v = len(li)
15 # print(v)
16 #
17 # li.append('seven')
18 # print(li)
19 #
20 # li.insert(0,'Tony')
21 # print(li)
22 #
23 # li[1] = 'Kelly'
24 #
25 # li.remove('eric')
26 # print(list)
27 #
28 # v = li.pop(1)
29 # print(v)
30 # print(li)
31 #
32 # del li[2]
33 
34 
35 # del li[0:2] # 0 =<x < 2
36 # print(li)
37 
38 # li.reverse()
39 # print(li)
40 
41 # for i in li:
42 #     print(i)

    5 range enumerate

     1 #/usr/bin/python
 2 # 1. 请输出1-10
 3 # 2.7: 立即生成所有数字
 4 # range(1,11) # 生成 1,23，，4,56.10
 5 
 6 # 3.x: 不会立即生成，只有循环迭代时，才一个一个生成
 7 # for i in range(1,11): #
 8 #     print(i)
 9 
10 # for i in range(1,11,2): #
11 #     print(i)
12 
13 # for i in range(10,0,-1): #
14 #     print(i)
15 
16 # 1. 3.x 不会立生成，迭代之后才一个一个创建；
17 """
18     - 2.7：
19         range()
20         xrange()  不会立生成，迭代之后才一个一个创建；
21     - 3.x
22         range()  不会立生成，迭代之后才一个一个创建；
23 """
24 # 2. range: 三个参数
25 #
26 # li = ['eric','alex','tony']
27 # # range,len,li循环
28 # for i in range(0,len(li)):
29 #     ele = li[i]
30 #     print(ele)
31 
32 
33 # li = ['eric','alex','tony']
34 # for i in li:
35 #     print(i)
36 
37 # for i in range(0,len(li)):
38 #     print(i+1,li[i])
39 
40 
41 # enumerate额外生成一列有序的数字
42 # li = ['eric','alex','tony']
43 # for i,ele in enumerate(li,1):
44 #     print(i,ele)
45 #
46 # v = input('请输入商品序号：')
47 # v = int(v)
48 # item = li[v-1]
49 # print(item)

    6 tuple 元祖

    不可被改变的列表，不可变类型

    6.1 count

    获取个数

    1 #/usr/bin/python
2 # user_tuple = ('alex','eric','seven','alex')
3 # v = user_tuple.count('alex')
4 # print(v)

    6.2 index

    获取值得第一个索引

    1 #/usr/bin/python
2 # user_tuple = ('alex','eric','seven','alex')
3 # v = user_tuple.index('alex')
4 # print(v)

    6.3 额外功能

     1 #/usr/bin/python
 2 # user_tuple = ('alex','eric','seven','alex')
 3 # for i in user_tuple:
 4 #     print(i)
 5 
 6 # v = user_tuple[0]
 7 
 8 # v = user_tuple[0:2]
 9 # print(v)
10 
11 # user_tuple = ('alex','eric','seven',['陈涛','刘浩','赵芬芬'],'alex')
12 # user_tuple[0] = 123   x
13 # user_tuple[3] = [11,22,33] x
14 # user_tuple[3][1] = '刘一'
15 # print(user_tuple)
16 
17 # li = ['陈涛','刘浩',('alex','eric','seven'),'赵芬芬']
18 # ****** 元组最后，加逗号 ******
19 # li = ('alex',)
20 # print(li)

    7 dict 字典

    可变类型

    7.1 clear

    清空

    1 #/usr/bin/python
2 # dic = {'k1':'v1','k2':'v2'}
3 # dic.clear()
4 # print(dic)

    7.2 copy

    浅拷贝

    1 #/usr/bin/python
2 # dic = {'k1':'v1','k2':'v2'}
3 # v = dic.copy()
4 # print(v)

    7.3 get

    获取key数据，不存在不报错

    1 #/usr/bin/python
2 # dic = {'k1':'v1','k2':'v2'}
3 # v = dic.get('k1111',1111)
4 # print(v)
5 # v = dic['k1111']
6 # print(v)

    7.4 pop

    删除并获取对应的value值

    1 #/usr/bin/python
2 # dic = {'k1':'v1','k2':'v2'}
3 # v = dic.pop('k1')
4 # print(dic)
5 # print(v)

    7.5 popitem

    随机删除键值对，并获取到删除的键值对

     1 #/usr/bin/python
 2 # dic = {'k1':'v1','k2':'v2'}
 3 # v = dic.popitem()
 4 # print(dic)
 5 # print(v)
 6 
 7 # k,v = dic.popitem() # ('k2', 'v2')
 8 # print(dic)
 9 # print(k,v)
10 
11 # v = dic.popitem() # ('k2', 'v2')
12 # print(dic)
13 # print(v[0],v[1])

    7.6 setdefault

    增加，如果存在不做任何操作

    1 #/usr/bin/python
2 # dic = {'k1':'v1','k2':'v2'}
3 # dic.setdefault('k3','v3')
4 # print(dic)
5 # dic.setdefault('k1','1111111')
6 # print(dic)

    7.7 update

    批量增加或修改

    1 #/usr/bin/python
2 # dic = {'k1':'v1','k2':'v2'}
3 # dic.update({'k3':'v3','k1':'v24'})
4 # print(dic)

    7.8 fromkeys

    生成字典

     1 #/usr/bin/python
 2 
 3 # dic = dict.fromkeys(['k1','k2','k3'],123)
 4 # print(dic)
 5 # dic = dict.fromkeys(['k1','k2','k3'],123)
 6 # dic['k1'] = 'asdfjasldkf'
 7 # print(dic)
 8 
 9 # dic = dict.fromkeys(['k1','k2','k3'],[1,])
10 # {
11 #    k1: 123123213, # [1,2]
12 #    k2: 123123213, # [1,]
13 #    k3: 123123213, # [1,]
14 # }
15 # dic['k1'].append(222)
16 # print(dic)

    7.9 额外功能

     1 #/usr/bin/python
 2 # - 字典可以嵌套
 3 # - 字典key: 必须是不可变类型
 4 # dic = {
 5 #     'k1': 'v1',
 6 #     'k2': [1,2,3,],
 7 #     (1,2): 'lllll',
 8 #     1: 'fffffffff',
 9 #     111: 'asdf',
10 # }
11 # print(dic)
12 # key:
13 #     - 不可变
14 #     - True,1
15 
16 # dic = {'k1':'v1'}
17 # del dic['k1']
18 
19 # 布尔值：
20 # 1 True
21 # 0 False
22 #
23 # bool(1111)

    8 set 集合

    不可重复的列表，可变类型

    8.1 difference

    集合1中存在 集合2中不存在或者是集合2中存在 集合1中不存在

    1 #/usr/bin/python
2 # s1 = {"alex",'eric','tony','李泉','李泉11'}
3 # s2 = {"alex",'eric','tony','刘一'}
4 # v = s1.difference(s2)
5 # print(v)

    8.2 difference_update

    集合1中存在，集合2中不存在，然后对集合1清空，然后再重新复制。

    集合2中存在，集合1中不存在，然后对集合2清空，然后再重新复制

    1 #/usr/bin/python
2 # s1 = {"alex",'eric','tony','李泉','李泉11'}
3 # s2 = {"alex",'eric','tony','刘一'}
4 # s1.difference_update(s2)
5 # print(s1)

    8.3 symmetric_difference

    1 #/usr/bin/python
2 # s1 = {"alex",'eric','tony','李泉','李泉11'}
3 # s2 = {"alex",'eric','tony','刘一'}
4 # v = s1.symmetric_difference(s2)
5 # print(v)

    8.4 交集

    1 #/usr/bin/python
2 # s1 = {"alex",'eric','tony','李泉','李泉11'}
3 # s2 = {"alex",'eric','tony','刘一'}
4 # v = s1.intersection(s2)
5 # print(v)

    8.5 union

    并集

    1 #/usr/bin/python
2 # s1 = {"alex",'eric','tony','李泉','李泉11'}
3 # s2 = {"alex",'eric','tony','刘一'}
4 # v = s1.union(s2)
5 # print(v)

    8.6 discard

    移除

    1 #/usr/bin/python
2 # s1 = {"alex",'eric','tony','李泉','李泉11'}
3 # s1.discard('alex')
4 # print(s1)

    8.7 update

    1 #/usr/bin/python
2 # s1 = {"alex",'eric','tony','李泉','李泉11'}
3 # s1.update({'alex','123123','fff'})
4 # print(s1)

    8.8 额外功能

    1 #/usr/bin/python
2 # s1 = {"alex",'eric','tony','李泉','李泉11'}
3 # for i in s1:
4 #     print(i)
5 
6 # s1 = {"alex",'eric','tony','李泉','李泉11',(11,22,33)}
7 # for i in s1:
8 #     print(i)
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  • 原文地址：https://www.cnblogs.com/ybyblog/p/6845946.html
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