day7 基础数据类型&集合&深浅拷贝

基础数据类型汇总:

#!/usr/bin/env python
# -*- coding:utf-8 -*-
 
'''
str     int
'''
# str
s = ' a'
print(s.isspace())
 
'''
list:
'''
li_st = [11, 22, 33, 44, 55]
for i in range(len(li_st)):  # range()也是顾头不顾尾
   del li_st[i]    #del操作会更新列表
 
删掉所有偶数
for i in li_st:
    if i % 2 == 0:
        del li_st[li_st.index(i)]
print(li_st)
 
dic = {'k1': 'v1', 'k2': 'v2', 'a3': 'v3'}
dic1 = {}
#循环字典过程中,不能删除字典的键值对;
for i in dic:
    if 'k' in i:
        del dic[i]
 
for i in dic:
    if 'k' not in i:
        dic1.setdefault(i, dic[i])
dic = dic1
print(dic)
 
l = []
for i in dic:
    if 'k' in i:
        l.append(i)
for i in l:
    del dic[i]
print(dic)
 
# 转换成bool是false:
#       0 '' [] () {} set()
 
# 元组 如果元组里面只有一个元素且不加 逗号, 则此元素是什么类型,就是什么类型
tu1 = (1)
tu2 = (1,)
print(tu1,type(tu1))
print(tu2,type(tu2))

集合:

#!/usr/bin/env python
# -*- coding:utf-8 -*-
 
'''
集合:
 可变的数据类型;可以增删改查
 储存元素必须是不可变的数据类型
 无序,不重复,
 {}
'''
 
set1 = set({1, 2, 3})
set2 = {1, 2, 3, [1, 2, 3], {'name': 'alex'}} #报错,集合中的元素必须是可哈希的
print(set1)
print(set2)
 
set1 = {'alex', 'wusir', 'ritian', 'egon', 'barry', 'barry'}
# 集合建立时可以重复元素,会在建立过程中自动去重操作
# 增
# add
set1.add('godress')
print(set1)
update
set1.update('abc')
print(set1)
 
# 删
# pop 随机删除,集合为空的时候报错
name = set1.pop( )
print(name)
print(set1)
 
# remove 按元素删除,元素不存在报错
set1.remove('barry')
print(set1)
 
# 清空列表
set1.clear()
print(set1)
 
# del 删除整个集合
del set1
print(set1)
 
# 查
# 只能用for循环查询
for i in set1:
    print(i)
 
# 集合运算
set1 = {1, 2, 3, 4, 5}
set2 = {4, 5, 6, 7, 8}
set3 = set1 & set2
# 交集
print(set1 & set2)
print(set1.intersection(set2))
 
# 反交集
print(set1 ^ set2)
print(set1.symmetric_difference(set2))
 
# 并集
print(set1 | set2)
print(set1.union(set2))
 
# 差集
print(set1 - set2)
print(set1.difference(set2))
 
# 子集
set4 = {1, 2}
set5 = {1, 2, 3}
print(set4 < set5)
print(set4.issubset(set5))
 
# 超集
set4 = {1, 2}
set5 = {1, 2, 3}
print(set5 > set4)
print(set5.issuperset(set4))
 
# 将集合变为不可变数据类型,即只读集合
s = frozenset('barry')
print(s, type(s))
# 只能查询
for i in s:
    print(i)

深浅拷贝:

#!/usr/bin/env python
# -*- coding:utf-8 -*-
 
# 赋值
# l1 = [1, 2, 3, ['a', 'b', 'c']]
# l2 = l1
# print('original L1:', l1)
# print('original L2:', l2)
#
# l2[3][0] = 'k'
# print('changed L2:', l2)
# print('changed L1:', l1)
#  因为赋值操作是直接把两个变量(L1,L2)同时指向同一个内存地址,所以动一发而牵全身
 
# 浅拷贝
# l1 = [1, 2, 3, ['a', 'b', 'c']]
# l2 = l1.copy()
# print('original L1:', l1)
# print('original L2:', l2)
#
# l2[0] = 4
# l2[3][1] = 'k'
# print('changed L2:', l2)
# print('changed L1:', l1)
#  浅拷贝:将拷贝对象的值拷贝到另一个内存地址,但是拷贝对象的子代仍是和原来指向同一个内存地址
 
# 深拷贝
# import copy
# l1 = [1, 2, 3, ['a', 'b', 'c']]
# l2 = copy.deepcopy(l1)
# print('original L1:', l1)
# print('original L2:', l2)
# l2[0] = 4
# l2[3][1] = 'k'
# print('changed L2:', l2)
# print('changed L1:', l1)
# print(l2 is l1)
# 深拷贝,将拷贝对象的值全部重新拷贝到新的内存地址里