初学python第四天

的一、列表

  append(末尾添加):

代码:

li = [12,22,33,"44","65"]
li.append(5)
print(li)
      结果:[12, 22, 33, '44', '65', 5]

  clear(清空):

代码:

li = [12,22,33,"44","65"]
li.clear()
print(li)
    结果:[]

  copy(拷贝,浅拷贝):

代码:

li = [12,22,33,"44","65"]
v = li.copy()
print(li)
print(v)
    结果:[12, 22, 33, '44', '65']
            [12, 22, 33, '44', '65']

   count(计算出现次数):

代码:

li = [12,22,33,"44","65"]
v = li.count(22)
print(v)
    结果:1

   extend(扩展了原列表):

代码:

li = [12,22,33,"44","65"]
li.extend([666,"aiankg"])
print(li)
    结果:[12, 22, 33, '44', '65', 666, 'aiankg']

  index(获取索引):

代码:

li = [12,22,33,"44","65"]
v = li.index(33)
print(v)
    结果:2

  insert(根据索引插入元素):

代码:

li = [12,22,33,"44","65"]
li.insert(2,"insert")
print(li)
    结果:[12, 22, 'insert', 33, '44', '65']

  pop(删除):默认最后一个删除,也可以指定索引

代码:

li = [12,22,33,"44","65"]
li.pop()
print(li)
    结果:[12, 22, 33, '44']
li = [12,22,33,"44","65"]
li.pop(2)
print(li)
    结果:[12, 22, '44', '65']

  remove(指定删除元素):

代码:

li = [12,22,33,"44","65"]
li.remove(33)
print(li)
       结果:[12, 22, '44', '65']

  reverse(反转):

代码:

li = [12,22,33,"44","65"]
li.reverse()
print(li)
    结果:['65', '44', 33, 22, 12]

  sort(从小到大排序):

代码:

li = [55,22,48,96,84,6,10]
li.sort()
print(li)
    结果:[6, 10, 22, 48, 55, 84, 96]

二、元组(末尾加,)

  元组形式:tu = (10,“55”,[12,"aiakng"],[(18)],)

    元组中列表只属于一个元素

  count(获取元素出现次数):

代码:

tu = (10,"55",[12,"aikang"],[(18)],)
v = tu.count(10)
print(v)
    结果:1

  index(索引):

代码:

tu = (10,"55",[12,"aikang"],[(18)],)
v = tu.index("55")
print(v)
    结果:1

三、字典

  字典结构:

                   键值对 

    info = {"k1":123,2:"234","3":["aikang"]}

   列表不能最作为字典的key,布尔值可以作为key使用要注意值和数字key重复,字典是无序列的,支持删除,支持for循环

    

  items(获取键值对):用列表输出。

代码:

info = {"k1":123,2:"234","3":["aikang"]}
v = info.items()
print(v)
    结果:dict_items([('k1', 123), (2, '234'), ('3', ['aikang'])])


info = {"k1":123,2:"234","3":["aikang"]}
for k ,v in info.items():
    print(k,v)
        结果:    k1 123
                    2     234
                    3    ['aikang']
          
 

   fromkeys(根据序列创建字典,并用统一值赋值):

代码:

info = {"k1":123,2:"234","3":["aikang"]}
v = info.fromkeys(["4",5,"hui"],987)
print(info)
print(v)
    结果:{'k1': 123, 2: '234', '3': ['aikang']}
             {'4': 987, 5: 987, 'hui': 987}  

  get(根据key获取值,如果不存在输出None)

代码:

info = {"k1":123,2:"234","3":["aikang"]}
v = info.get("k1")
print(v)
i = info.get("k8")
print(i)
    结果:123
            None

  pop(删除key指定,如果不存在输出指定值)

代码:

info = {"k1":123,2:"234","3":["aikang"]}
v = info.pop("k1",90)
print(v)
print(info)
    结果:    123
                {2: '234', '3': ['aikang']}    

  popitem(随机返回并删除字典中的一对键和值):

代码;

info = {"k1":123,2:"234","3":["aikang"]}
v = info.popitem()
print(v)
print(info)
    结果:('3', ['aikang'])
            {'k1': 123, 2: '234'}

  setdefault(设置值):

    说明:

        已存在值,不设置,获取当前key对应的值,

        不存在值,设置值,获取当前key对应的值 

代码:

info = {"k1":123,2:"234","3":["aikang"]}
v = info.setdefault("k1","love")
print(info)
print(v)
    结果:{'k1': 123, 2: '234', '3': ['aikang']}
            123

i = info.setdefault("k5","love")
print(info)
print(i)
    
    结果:{'k1': 123, 2: '234', '3': ['aikang'], 'k5': 'love'}
              love    

  update(跟新):

    记得大括号

代码:

info = {"k1":123,2:"234","3":["aikang"]}
info.update({"k1":258})
print(info)
    结果:{'k1': 258, 2: '234', '3': ['aikang']}

keys() values() items() get update 最重要

 

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转载自www.cnblogs.com/aikang525/p/10220800.html