Python基础day-4[dict,set,bool]

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布尔类型:

  True和False

  所有的数据类型自带布尔值,只有0,None,空的布尔值为False

字典dict:

  特性:dict中使用key和对应的value来存储数据,dict不像 list那样,数据越多查询越慢.dict中key必须是不可变类型,或者说必须是可hash类型.value的值是可以改变的,可以是任意类型的数据.字典的取值是无序的.无法通过索引取值.

  定义dict:

  d = {key:value,key:value,key:value}

  d = {‘name‘:‘abc‘,‘age‘:18,1:‘id‘}

  新增:

  d = {}

  d[‘x‘] = 1

  取值: 通过key取值

  print(d[‘name‘])

  print(d[1])

  循环:

  for i in d:
  print(i)     #利用for循环取直接取字典内容,只能取出字典的key
  print(d[i])  #利用取出的key,打出对应的value

  嵌套使用:  list和字典可以互相套,list中可以有字典,字典的value也可以是列表,注意:list是不可hash类型,也就说不能作为key

  user_info=[                 #定义一个列表,列表中使用字典存储用户名和密码
  {‘username‘:‘egon‘,‘password‘:‘123‘},
  {‘username‘:‘alex‘,‘password‘:‘alex3714‘},
  {‘username‘:‘yuanhao‘,‘password‘:‘sb123‘},
  ]
  for item in user_info:     #for循环提取list中的dict
  print(item[‘username‘],item[‘password‘])   #打印dict中的 username和password

  成员运算:

  d = {‘x‘:1,‘u‘:2}

  print(‘x‘ in d)

  print(1 in d.values())

  dict的常用操作:

    d.clear():清空字典的所有内容

    d = {‘name‘:‘abc‘,‘age‘:18,1:‘id‘}
    d.clear()
    print(d)

D:\Python\Python36-32\python.exe E:/Python/tmp.py
{}

Process finished with exit code 0

    d.get():带返回值的取值方式,当取出不存的值时会返回None 不会报错

    d = {‘name‘:‘abc‘,‘age‘:18,1:‘id‘}
    print(d.get(‘abc‘))

D:\Python\Python36-32\python.exe E:/Python/tmp.py
None

Process finished with exit code 0

    d.items():以元组的方式显示键值对,for循环时可以给两个变量,同时取出key和value

    d = {‘name‘:‘abc‘,‘age‘:18,1:‘id‘}
    for k,v in d.items():
    print(k,v)
    print(‘==================‘)
    for i in d.items():
    print(i)

D:\Python\Python36-32\python.exe E:/Python/tmp.py
name abc
age 18
1 id
==================
(name, abc)
(age, 18)
(1, id)

Process finished with exit code 0

    d.keys and d.values:指定提取全部的key或者value

    d = {‘name‘:‘abc‘,‘age‘:18,1:‘id‘}
    print(d.keys())
    print(d.values())

D:\Python\Python36-32\python.exe E:/Python/tmp.py
dict_keys([name, age, 1])
dict_values([abc, 18, id])

Process finished with exit code 0

    d.pop():pop是带返回值的,精确删除某个key

    d = {‘name‘:‘abc‘,‘age‘:18,1:‘id‘}
    print(d.pop(‘age‘))        #pop()必须给予一个key,否则报错
    print(d)
    print(d.pop(‘abc‘,‘没有abc那个key‘))  #由于pop带返回值,所以可以指定返回信息,来去除错误信息.不指定返回值,当删除一个不存在的key时会报错.

D:\Python\Python36-32\python.exe E:/Python/tmp.py
18
{name: abc, 1: id}
没有abc那个key

Process finished with exit code 0

    d.popitem():随机删除一组key和对应的value

    d = {‘name‘:‘abc‘,‘age‘:18,1:‘id‘}
    d.popitem()
    print(d)

D:\Python\Python36-32\python.exe E:/Python/tmp.py
{name: abc, age: 18}

Process finished with exit code 0

    d.setdefault():向dict中添加key和对应的value,如果key已存在则不添加(也不会报错.)

    d = {‘name‘:‘abc‘,‘age‘:18,1:‘id‘}
    d.setdefault(‘aaa‘,111)
    print(d)
    d.setdefault(‘name‘,‘abc‘)
    print(d)
    d.setdefault(‘name‘,‘abc123‘)
    print(d)

D:\Python\Python36-32\python.exe E:/Python/tmp.py
{name: abc, age: 18, 1: id, aaa: 111}
{name: abc, age: 18, 1: id, aaa: 111}
{name: abc, age: 18, 1: id, aaa: 111}

Process finished with exit code 0

    几种新建字典的方式:

d1={}
d2=dict()
print(d1,d2)
d3=dict(x=1,y=2,z=3)
print(d3)
d4=dict({x:1,y:2,z:3})
print(d4)
d5=dict([(‘x‘,1),(‘y‘,2),(‘z‘,3)])
print(d5)
D:\Python\Python36-32\python.exe E:/Python/tmp.py
{} {}
{x: 1, y: 2, z: 3}
{x: 1, y: 2, z: 3}
{‘x‘: 1, ‘y‘: 2, ‘z‘: 3} Process finished with exit code 0

    d.fromkeys(): 创建的dict的格式化,前面所有的key匹配同一个value

    d={}.fromkeys([‘name‘,‘age‘],None)
    print(d)

D:\Python\Python36-32\python.exe E:/Python/tmp.py
{name: None, age: None}

Process finished with exit code 0

    d.update():更新列表,没有的key就添加,key如果存在就更新value

    d = {‘name‘:‘abc‘,‘age‘:18,1:‘id‘}
    d1 = {‘name‘:‘ac‘,1:‘i‘}

    d1.update(d)
    print(d1)

D:\Python\Python36-32\python.exe E:/Python/tmp.py
{name: abc, 1: id, age: 18}

Process finished with exit code 0

 

集合set:

  特性:集合内的元素必须是唯一的,集合内的元素必须是可hash的,也就是不可变类型,集合是无序的

  定义集合:

  s = {‘abc‘,1,‘aaa‘,(1,2),‘name‘}

 集合的作用:

  1.去重    #因为集合的元素是唯一的所以可用于去除重复的元素.

  2.关系运算:

    python_s={‘egon‘,‘alex‘,‘abc‘,‘wang‘}
    linux_s={‘alex‘,‘abc‘,‘aaa‘,‘bbb‘}
    # 取共同部分:交集
    print(python_s & linux_s)
    #取老男孩所有报名学习的学生:并集
    print(python_s | linux_s)
    #取只报名了python课程的学生:差集
    print(python_s - linux_s)
    # 取只报名了linux课程的学生:差集
    print(linux_s - python_s)
    # 取没有同时报名python和linux课程的学:对称差集
    print(linux_s ^ python_s)

D:\Python\Python36-32\python.exe E:/Python/tmp.py
{abc, alex}
{wang, bbb, abc, aaa, egon, alex}
{egon, wang}
{aaa, bbb}
{aaa, egon, wang, bbb}

Process finished with exit code 0

 

  集合的操作:

    关系运算
    python_s={‘egon‘,‘alex‘,‘abc‘,‘wang‘}
    linux_s={‘alex‘,‘abc‘,‘aaa‘,‘bbb‘}

    print(python_s.intersection(linux_s))  # 交集:python_s & linux_s
    print(python_s.union(linux_s))    #并集:|
    print(python_s.difference(linux_s))   #python_s-linux_s
    print(python_s.symmetric_difference(linux_s))  # 对称差集,python_s ^ linux_s

D:\Python\Python36-32\python.exe E:/Python/tmp.py
{abc, alex}
{wang, egon, abc, alex, bbb, aaa}
{wang, egon}
{bbb, wang, egon, aaa}

Process finished with exit code 0

    s.difference_update():差集更新

    python_s={‘egon‘,‘alex‘,‘abc‘,‘wang‘}
    linux_s={‘alex‘,‘abc‘,‘aaa‘,‘bbb‘}

    python_s.difference_update(linux_s)
    print(python_s)

D:\Python\Python36-32\python.exe E:/Python/tmp.py
{wang, egon}

Process finished with exit code 0

    s.update():更新,如果没有添加

    s1={‘a‘,1}
    s2={‘a‘,‘b‘,2}

    s1.update(s2)
    print(s1)

D:\Python\Python36-32\python.exe E:/Python/tmp.py
{1, 2, b, a}

Process finished with exit code 0

    s.add():添加一个元素

    s={‘a‘,1}
    s.add(‘abc‘)
    print(s)

D:\Python\Python36-32\python.exe E:/Python/tmp.py
{1, a, abc}

Process finished with exit code 0

    s.discard():删除一个指定的元素,删除不存在元素时不会报错

    s={‘a‘,1}
    s.discard(‘a‘)
    print(s)

D:\Python\Python36-32\python.exe E:/Python/tmp.py
{1}

Process finished with exit code 0

    s.remove():删除一个指定元素,删除不存在的元素时会报错

    s={‘a‘,1}
    s.remove(‘a‘)
    print(s)

D:\Python\Python36-32\python.exe E:/Python/tmp.py
{1}

Process finished with exit code 0

    s.pop():随机删除一个元素

    s={‘a‘,2,3,4,5,6,7,8,9}
    print(s.pop())
    print(s)

D:\Python\Python36-32\python.exe E:/Python/tmp.py
a
{2, 3, 4, 5, 6, 7, 8, 9}

Process finished with exit code 0

    s.issubset():判断是否是子集

    s.issuperset():判断是否是父集

    s1={1,2,}
    s2={1,2,3}

    print(s1.issubset(s2))
    print(s2.issuperset(s1))

D:\Python\Python36-32\python.exe E:/Python/tmp.py
True
True

Process finished with exit code 0

    s.isdisjoint():没有交集返回True

    s1={‘a‘,‘b‘}
    s2={1,2,3}

    print(s1.isdisjoint(s2))

D:\Python\Python36-32\python.exe E:/Python/tmp.py
True

Process finished with exit code 0

 



































































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