python学习第七天 基础数据类型补充 深浅copy 集合 关键字后面加可迭代对象

list1=[1,2,3]
list2=[‘a‘,‘b‘]
list3=list1+list2
print(list3)
#[1, 2, 3, ‘a‘, ‘b‘]

# 删除列表中偶数索引对应的元素
# 方法1:新建一个列表,将奇数索引对应的元素添加进去
list1=[1,2,3,4,5,6,7]
list2=[]
for i in list1:
    if list1.index(i) % 2 == 1:
        list2.append(i)
print(list2

# 方法2:从列表的最后开始删
list1=[1,2,3,4,5,6,7]
for i in range(len(list1)-1,-1,-1):
    if i % 2 == 0:
        list1.pop(i)
print(list1)

# 方法3
# list1=[1,2,3,4,5,6,7]
# del list1[0::2]
# print(list1)

# 删除字典中含k的键
# 方法1:将keys提取到列表中,循环去除
dic={‘k1‘:1,‘k2‘:2,‘name‘:3}
list1=list(dic.keys())
for i in list1:
    if ‘k‘ in i:
        dic.pop(i)
print(dic)

# # 方法2
# dic={‘k1‘:1,‘k2‘:2,‘name‘:3}
# dic2={}
# for k in dic.keys():
#     if ‘k‘ not in k:
#         dic2.setdefault(k,dic[k])
# print(dic2)

# dic3=dict.fromkeys([‘key1‘,‘key2‘,‘key3‘],[])
# dic3[‘key1‘]=‘alex‘
# print(dic3)
#{‘key1‘: ‘alex‘, ‘key2‘: [], ‘key3‘: []}

# dic3=dict.fromkeys([‘key1‘,‘key2‘,‘key3‘],[])
# dic3[‘key1‘].append(‘1‘)
# print(dic3)
#{‘key1‘: [‘1‘], ‘key2‘: [‘1‘], ‘key3‘: [‘1‘]}

dic3=dict.fromkeys([‘key1‘,‘key2‘,‘key3‘],‘egon‘)
print(dic3)
#{‘key1‘: ‘egon‘, ‘key2‘: ‘egon‘, ‘key3‘: ‘egon‘}

# 方法1:利用set去重
list1=[‘alex‘,‘egon‘,1,‘alex‘]
set1=set(list1)
list1=list(set1)
print(list1)

# 方法2:利用for循环去除
list1=[‘alex‘,‘egon‘,1,‘alex‘]
list2=[]
for i in list1:
    if i not in list2:
        list2.append(i)
print(list2)

list1=[‘alex‘,‘egon‘,‘alex‘]
s=‘_‘.join(list1)
print(s)

list1=[1,2,3]
list2=list1.copy()
print(id(list1),id(list2))
print(id(list1[0]),id(list2[0]))
#1866482736328 1866482736264
#1887330528 1887330528

import copy
list1=[1,2,3]
list2=copy.deepcopy(list1)
print(id(list1),id(list2))
print(id(list1[0]),id(list2[0]))