第六天知识总结

集合：可变的数据类型，它里面的元素必须是不可变的数据类型，无序，不重复

# 创建方法：1.set1 = set({1,2,3})    2.set1 = {}
# 增  随机增加
set1 = {'jack','tom','join','jin'}
set1.add('刘')
print(set1)
set1.update('abc')
print(set1)

# 删
set1 = {'jack','tom','join','jin'}
print(set1.pop())  # 随机删除,有返回值
print(set1)
set1.remove('jack')    # 按元素去删
print(set1)
set1.clear()           # 清空集合
print(set1)
del set1           # 删除整个集合
print(set1)

# 查
set1 = {'jack','tom','join','jin'}
for i in set1:
    print(i)

# 没有改，但可以求交集，并集等
set2 ={1,2,3,4,6}
set3 ={1,2,7,8,9}
print(set2 & set3)           # (交集)或者print(set2.intersection(set3))
print(set2 | set3)           # (并集)或者print(set2.union(set3))
print(set2 ^ set3)           # (反交集)或者print(set2.symmetric_difference(set3))
print(set2 - set3)           # (差集)或者print(set2.difference(set3)),意思是set2里面独有的
print(set2 < set3)           # (子集)或者print(set2.issubset(set3))，意思是set3里面包含了set2
print(set2 > set3)           # (超集)或者print(set2.issuperset(set3))

# 去重
例子：去除列表中重复的数字li=[1,2,2,3,4,5,5,77,77,9]
li = [1,2,2,3,4,5,5,77,77,9]
set1 = set(li)
li = list(set1)
print(li)

# 变成不可变数据类型,也是无序
set4 = frozenset('jack')
print(set4,type(set4))

深浅copy

# 1.浅拷贝只是在内存中重新创建了开辟了一个空间存放一个新列表，但是新列表中的元素与原列表中的元素是公用的。
# 同一代码块下：
l1 = [1, '天空', True, (1,2,3), [22,33]]
l2 = l1.copy()
print(id(l1),id(l2))  # 2713214468360 2713214524680
print(id(l1[-2]),id(l2[-2]))  # 2547618888008 2547618888008
print(id(l1[-1]),id(l2[-1]))  # 2547620322952 2547620322952
# 不同代码块下(终端操作)：
l1 = [1, '天空', True, (1, 2, 3), [22, 33]]
l2 = l1.copy()
print(id(l1), id(l2))                 # 1477183162120 1477183162696
print(id(l1[-2]), id(l2[-2]))         # 1477181814032 1477181814032
print(id(l1[-1]), id(l2[-1]))         # 1477183162504 1477183162504

# 2.深拷贝deepcopy。
# 同一代码块下
import copy
l1 = [1, 'alex', True, (1,2,3), [22,33]]
l2 = copy.deepcopy(l1)
print(id(l1), id(l2))  # 2788324482440 2788324483016
print(id(l1[0]),id(l2[0]))  # 1470562768 1470562768
print(id(l1[-1]),id(l2[-1]))  # 2788324482632 2788324482696
print(id(l1[-2]),id(l2[-2]))  # 2788323047752 2788323047752
# 不同代码块下(终端操作)
import copy
l1 = [1, '天空', True, (1, 2, 3), [22, 33]]
l2 = copy.deepcopy(l1)
print(id(l1), id(l2))          # 1477183162824 1477183162632
print(id(0), id(0))            # 1470562736 1470562736
print(id(-2), id(-2))          # 1470562672 1470562672
print(id(l1[-1]), id(l2[-1]))  # 1477183162120 1477183162312

循环删除

# 列表
li = [1,2,3,4,5]
lst2 = li.copy()
for w in lst2:
    li.remove(w)
print(li)
# 字典
dic = {'name':'jack','age':18,'hobby':'game'}
lst = []
for w in dic.keys():
    lst.append(w)
for w in lst:
    dic.pop(w)
print(dic)

删除含有K的键值对
# 方法1
dic1 = {'k1':'v1','k2':'v2','k3':'v3','a1':'v4'}
dic1_1 = {}
for i in dic1.keys():
    if 'k' not in i:
        dic1_1.setdefault(i,dic1[i])
dic1 = dic1_1
print(dic1)
# 方法2
dic1 = {'k1':'v1','k2':'v2','k3':'v3','a1':'v4'}
li = []
for i in dic1:
    if 'k' in i:
        li.append(i)
for i in li:
    del dic1[i]
print(dic1)


# 转化为bool值
# 除了0，'',[],{},(),set(),里面为空就是F,其余都是T