print()函数查看帮助文件

>>> help(print) Help on built-in function print in module builtins: print(...) print(value, ..., sep=' ', end='\n', file=sys.stdout, flush=False) Prints the values to a stream, or to sys.stdout by default. Optional keyword arguments: file: a file-like object (stream); defaults to the current sys.stdout. sep: string inserted between values, default a space. end: string appended after the last value, default a newline. flush: whether to forcibly flush the stream. >>>

语法格式：

print(value, ..., sep=' ', end='\n', file=sys.stdout, flush=False)

等价于

print(value1,value2,...,valuen,sep=' ', end='\n', file=sys.stdout, flush=False)

demo:

>>> a,b,c,*d = 1,2,3,4,5,6 >>> a 1 >>> b 2 >>> c 3 >>> d [4, 5, 6] >>> print(a,b,c,d) 1 2 3 [4, 5, 6] >>> print(a,b,c,d,sep="#") 1#2#3#[4, 5, 6] >>> for i in range(5): ... print(i) ... 0 1 2 3 4 >>> for i in range(5): ... print(i,end=" ") ... 0 1 2 3 4 >>> >>> for i in range(5): ... print(i,end="#") ... 0#1#2#3#4#>>>

格式化字符串

%号格式化

占位符

格式描述%d有符号的整数%s字符串%c字符及ASCII码%o无符号的八进制整数%x/%X无符号的十六进制整数%e/%E浮点数，科学计数法%f浮点数

%格式化字符串 用%匹配参数，注意个数一一对应

print("%d%%" % 100) # %% 转译出% 100%

format格式化

(1)位置映射

print("{}:{}".format("Tom",18)) print("name:{},age:{}".format("Tom",18)) Tom:18 name:Tom,age:18

(2)关键字映射

print("{address}，name:{},age:{}".format("Tom",18,address = '后面关键字必须在最后')) 后面关键字必须在最后，name:Tom,age:18

(3)元素访问

print("第一个元素是:{0[0]},第二个元素是:{0[1]},第三个元素是:{0[2]}.".format(('www.','4399.','com')))

列表

列表由方括号括起来的[],每个元素以逗号分隔；

可以储存不同的数据类型数据

特点 有序可重复可变类型

1.创建空列表

li = [] print(type(li))

2.创建多元素列表

li = [1,2,3,"abc",[4,5,6],['A']]

3.强转

sr = "abc" li = list(sr) print(li) ['a', 'b', 'c']

4.拼接

li1 = ["I"] li2 = ["Love"] li3 = ["Python"] print(li1+li2+li3) ['I', 'Love', 'Python']

5.重复

li = ["啊啊"] print(li * 3) ['啊啊', '啊啊', '啊啊']

6.索引(偏移) [] 切片[:] [::]

li = ["z","u","c","c","zucc",["very","nice"]] print(len(li)) print(li[0],li[-4]) print(li[:3]) print(li[::-1]) print(li[4][3]) print(li[5][1]) 6 z c ['z', 'u', 'c'] [['very', 'nice'], 'zucc', 'c', 'c', 'u', 'z'] c nice

7.增删改查

7.1增

append()extend()insert() li = [1,2] print(id(li)) li1 = ['z','u','c','c'] li.append(li1) print(li,id(li)) 1766771992584 [1, 2, ['z', 'u', 'c', 'c']] 1766771992584 li = [1,2] li1 = ['z','u','c','c'] li.extend(li1) print(li) [1, 2, 'z', 'u', 'c', 'c'] li = [1,2] li1 = ['z','u','c','c'] li.insert(0,li1) print(li) [['z', 'u', 'c', 'c'], 1, 2]

7.2改

li = ['z','u','c','c',['i','love'],'you'] li[1] = 'z' li[4:6] = [['very'],'nice'] print(li) ['z', 'z', 'c', 'c', ['very'], 'nice']

7.3删除

pop() ，返回被删除的元素

如果不指定索引，默认删除最后一个元素

删除指定索引对应元素

li = ['z','u','c','c',['i','love'],'you'] print(li.pop()) print(li) you ['z', 'u', 'c', 'c', ['i', 'love']] li = ['z','u','c','c',['i','love'],'you'] print(li.pop(1)) print(li) u ['z', 'c', 'c', ['i', 'love'], 'you'] remove()，移除第一次遇到的指定元素 li = ['z','u','c','c',['i','love'],'you'] li.remove('c') print(li) ['z', 'u', 'c', ['i', 'love'], 'you'] del li = ['z','u','c','c',['i','love'],'you'] del li[2:5] print(li) ['z', 'u', 'you'] #若 del li 则name 'li' is not defined clear()，清空 li = ['z','u','c','c',['i','love'],'you'] li.clear() print(li) []

7.4遍历

索引，切片遍历 元素遍历索引遍历枚举遍历 enumerate()， 对于一个可迭代的/可便利的对象（如列表，字符串），将其组成一个索引序列，利用它，我们可以同时获得索引和值 li = ['z','u','c','c',['i','love'],'you'] for i in li: print(i) z u c c ['i', 'love'] you li = ['z','u','c','c',['i','love'],'you'] for i in range(len(li)): print(li[i]) z u c c ['i', 'love'] you li = ['z','u','c','c',['i','love'],'you'] for index,value in enumerate(li): print(index,value) 0 z 1 u 2 c 3 c 4 ['i', 'love'] 5 you

8.堆和栈

9.其他操作

9.1计数，count(),查找元素出现的次数

9.2反转，reverse()

li = ['z','u','c','c',['i','love'],'you'] print(li) li.reverse() print(li) ['z', 'u', 'c', 'c', ['i', 'love'], 'you'] ['you', ['i', 'love'], 'c', 'c', 'u', 'z']

9.3排序，sort(),列表内需要是同一种数据类型

li = [['i','love'],['a'],['z']] print(li) li.sort() print(li) [['i', 'love'], ['a'], ['z']] [['a'], ['i', 'love'], ['z']] #输出两个列表的交集 li1 = ['a','b','c','d'] li2 = ['c','d','e','f'] li = [] for i in li1: if i in li2: li.append(i) print(li) ['c', 'd']

9.4赋值与拷贝

赋值：对对象的引用深浅拷贝 浅拷贝会创建新对象，内容是原对象的引用

切片[:]

工厂函数list (li)

copy模块内的copy函数

la = [1,2,3,4,5,6,7,'a',['b1','b2']] lb = la lb2 = la[:] print(id(la)) print(id(lb2)) import copy lb_copy = copy.copy(la) print(id(la)) print(id(lb_copy)) la.append('text') print(la) print(lb_copy) la[8][1] = 'c' print(la) print(lb) 2152543679240 2152543680904 2152543679240 2152543680648 [1, 2, 3, 4, 5, 6, 7, 'a', ['b1', 'b2'], 'text'] [1, 2, 3, 4, 5, 6, 7, 'a', ['b1', 'b2']] [1, 2, 3, 4, 5, 6, 7, 'a', ['b1', 'c'], 'text'] [1, 2, 3, 4, 5, 6, 7, 'a', ['b1', 'c'], 'text']

浅拷贝相当于我们只拷贝了一层，修改外层元素，会修改引用，让她们指向另一个位置；修改嵌套列表的元素，列表地址没有发生变化，指向还是一个位置。所以修改内部嵌套内容会同时变化。

深浅拷贝

深拷贝 import copy la = [1,2,3,4,5,6,7,'a',['b1','b2']] lb_deepcopy = copy.deepcopy(la) print(la,id(la)) print(lb_deepcopy,id(lb_deepcopy)) la[8][1]= 'c' print(la) print(lb_deepcopy) [1, 2, 3, 4, 5, 6, 7, 'a', ['b1', 'b2']] 2706895534472 [1, 2, 3, 4, 5, 6, 7, 'a', ['b1', 'b2']] 2706895534280 [1, 2, 3, 4, 5, 6, 7, 'a', ['b1', 'c']] [1, 2, 3, 4, 5, 6, 7, 'a', ['b1', 'b2']]

深拷贝拷贝所有对象，包括嵌套元素，创建一个全新的地址，所以修改原内部嵌套内容不会发生连变

列表生成式

用来生成列表的特定的语法形式

格式：

[表达式 for 迭代元素 in 可迭代对象]

实现原理

- 迭代[可迭代对象]中的每一个元素 - 每迭代一次的结果赋值给对应的迭代元素，在通过表达式运算得到一个新的值 - 最后所有通过表达式计算的值以一个列表的形式返回 print([x for x in range(10) if x%2==0]) [0, 2, 4, 6, 8] sr = '城市学院' print([ord(x) for x in sr]) [22478, 24066, 23398, 38498] li = [22478, 24066, 23398, 38498] print([chr(x) for x in li]) ['城', '市', '学', '院']

带过滤功能格式：

[exp for iter_val in iter if if_condtion]

相当于：

li = [] for iter_val in iter: if if_condtion li.append(iter_val) print(li) name = ["1","2","3"] subject = ["4","5","6"] li = [] for i in name: for j in subject: li.append([i,j]) print(li) print([[i,j] for i in name for j in subject]) [['1', '4'], ['1', '5'], ['1', '6'], ['2', '4'], ['2', '5'], ['2', '6'], ['3', '4'], ['3', '5'], ['3', '6']] [['1', '4'], ['1', '5'], ['1', '6'], ['2', '4'], ['2', '5'], ['2', '6'], ['3', '4'], ['3', '5'], ['3', '6']]

元组

有序可重复不可更改

符号使用 ()

定义：由小括号括起来的(),每个元素以逗号分隔；

1.创建空元组

tp = () print(type(tp))

2.创建单元素元组

单元素之后必须加逗号！

tp = ('123',) print(type(tp)) <class 'tuple'>

3.创建多元素元组

4.拼接

tp = ('123','a','b','c','d') tp1 = ('456',) print(tp+tp1) ('123', 'a', 'b', 'c', 'd', '456')

5.重复

tp = ('123','a','b','c','d') tp1 = ('456',) print(tp*3) ('123', 'a', 'b', 'c', 'd', '123', 'a', 'b', 'c', 'd', '123', 'a', 'b', 'c', 'd')

6.索引（偏移） 切片[:]

tp = ('123','a','b','c','d') tp1 = ('456',) tp2 = ('123','a','b','c',['ccc','bbb']) print(tp+tp1) print(tp*3) print(tp[2]) print(tp[::-1]) tp2[4][0] = 'aaa' print(tp2[4][0]) print(tp2) ('123', 'a', 'b', 'c', 'd', '456') ('123', 'a', 'b', 'c', 'd', '123', 'a', 'b', 'c', 'd', '123', 'a', 'b', 'c', 'd') b ('d', 'c', 'b', 'a', '123') aaa ('123', 'a', 'b', 'c', ['aaa', 'bbb'])

7.查删

使用index和切片查

tp = ('123','a','b','c',['ccc','bbb']) print(tp.index('123')) 0 tp2 = ('123','a','b','c',['ccc','bbb']) print(tp2[2:3]) ('b',)

整体删除

tp = ('123','a','b','c',['ccc','bbb']) del tp

8.判断

tp = ('123','a','b','c',['ccc','bbb']) print('a' in tp) True

9.最大值，最小值

tp1 = ('a','b','c','d') print(max(tp1),min(tp1)) d a

10.遍历

元素遍历 tp1 = ('a','b','c','d') for i in tp1: print(i) a b c d 索引遍历 tp1 = ('a','b','c','d') for i in range(len(tp1)): print(tp1[i]) a b c d 枚举enumerate tp1 = ('a','b','c','d') for index,value in enumerate(tp1): print(index,value) 0 a 1 b 2 c 3 d