对列表、元组、字典、集合、布尔类型认识

一、列表类型(list)

  简述:可以存储多个元素,其形式是以[]包裹的元素,其中的元素可以是任何类型的元素可以用来表示一个人的爱好。

hobby=["pingpang","apple","red","blue"]

1、以索引取值

print(hobby[0]) #["pingpang"]

print(hobby[:2])#["pingpang","apple"]

print(hobby[:-1])#["pingpang","apple"]

2、切片

print(hobby[::2])#["pingpang","red"]

print(hobby[::-1])#["blue","red","apple","pingpang"]

3、in 和not in

print("pingpang" not in hobby)# False

print("pingpang" in hobby)#True

4、添加 append

hobby.append("aaa")

print(hobby)#["pingpang","apple","red","blue","aaa"]

5、删除del、remove、pop

del hobby[0] #["apple","red","blue"]

hobby.pop(0)#["apple","red","blue"]

hobby.remove("pingpang")#["apple","red","blue"]

6、for循环

for i in hobby:

  print(i)

7、长度len()

print(len(hobby))#4

二、元组(tuple)

  简述:其书写形式就是将列表的[]换成()其取值方式跟列表基本一样,元组内部的元素都是不可变类型的元素可以被用做字典的key值。

1、按索引取值

2、切片

3、not in和 in

4、for循环

5、长度len()

三、字典(dict)

  简述:其书写方式为{key:value},每个value都有一个个与其一一对应的key这样取值快,一般字典可以用来存储一个人身份证号。

name={"liu":00,"xing":25,"age":20}

1、按key取值

print(name["liu"])#00

2、not in 和 in

print("liu" in name.keys)#True

print(00 not in name.values)#False

3、keys键、values值、items键值对

for key in name.keys():

  print(key)#liu、xing、age

for value in name.values():

  print(value)#00、25,、20

for item in name.items():

  print(item)#("liu",00)、("xing",25)、("age",20)

for k,v in name.items():
  print(k,v)#"liu",00,"xing",25,"age",20

4、删除 pop、popitem

name.pop("liu")#00

name.popitem()#随机删除一个字典内的元素

5、通过fromkeys将列表转成字典

l=["age","liu","xing"]

dict={}

dict.fromkeys(l,20)

print(dict)#{"age":20,"liu":20,"xing":20}

6、setdefault:

name.setdefault("liu",20)#没有变化

name.setdefault("cheng",33)#{"liu":00,"xing":25,"age":20,"cheng":33}

四、集合(set)

·简述:以{}包裹的书写方式,在集合中的元素都应该定义成不可变类型并且集合中的元素都是无序、重复的。

n1={1,2,3,7,8,9}

n2={4,5,6,7,8,9}

1、并集 |

print(n1|n2)#{1,2,3,4,5,6,7,8,9}

2、差集 -

print(n1-n2)#{1,2,3}

3、对称差集 ^

print(n1^n2)#{1,2,3,4,5,6}

4、交集 &

print(n1&n2)#{7,8,9}

5、子集 issubset

print(n1.issubset(n2))#False

6、父集issuperset

print(n1.issuperset(n2))#False

五、布尔(bool)

  简述:除0、None、空,外其他的变量都是True。

补充:

  可变类型:指的是value发生变化但变量的id不会发生变化。(引用传递、深拷贝)(字典、列表)

  不可变类型:指的是value发生变化其变量的id也会发生变化。(值传递,浅拷贝)(字符串、集合、元组)

原文地址:https://www.cnblogs.com/ageliu/p/12335307.html