python爬虫学习——元组，字典（2.14日博客补）

元组

"""
tup1 = ()          #创建一个空的元组
print(type(tup1))

#tup2 = (50)     #不是元组，python把括号当成了表达式的一部分，即数学运算的括号
#tup2 = (50,)
tup2 = (50,60,70)
print(type(tup2))
"""
"""
tup1 = ("abc","def",2020,2023,111,222,333)
print(tup1[0])
print(tup1[-1])
print(tup1[1:5]) #左闭右开，进行切片
"""

# 增 (连接)
"""
tup1 = (60,70,80)
tup2 = ("abc","xyz")
tup = tup1 + tup2
print(tup)
"""

# 删 只能删除整个元组
"""
tup1 = (60,70,80)
print(tup1)
del tup1
print("删除后：",tup1)
"""

# 改
"""
tup1 = (50,60,70)

tup1[0] = 100  #报错，元组不允许修改
"""
# 查 直接输出下标
tup1 = ("abc","def",2020,2023,111,222,333)
print(tup1[0])

字典

即键值对，键必须是唯一的

"""
#字典的定义
info = {"name":"吴彦祖","age":18}

#字典的访问
print(info["name"])
print(info["age"])


# 访问不存在的键
#print(info["gender"])          #直接访问会报错
#print(info.get("gender"))       #使用get方法，访问不存在的键，默认返回：None

print(info.get("age",20))
print(info.get("gender","m"))      #没找到，可以设定默认值
"""

# 增
"""
info = {"name":"吴彦祖","age":18}
newID = input("请输入：")
info["id"] = newID
print(info["id"])
"""
# 删
"""
#del 删除
info = {"name":"吴彦祖","age":18}
print("删除前:%s"%info["name"])
del info["name"]            #删除了整个键值对
print("删除后%s"%info["name"])  #再次访问会报错

info = {"name":"吴彦祖","age":18}
print("删除前:%s"%info)
del info
print("删除后:%s"%info)

#clear 清空
info = {"name":"吴彦祖","age":18}
print("清空前:%s"%info)
info.clear()
print("清空后:%s"%info)
"""
# 改 直接改
"""
info = {"name":"吴彦祖","age":18}
info["age"] = 20
print(info["age"])
"""
# 查 (遍历)
"""
info = {"id":1,"name":"吴彦祖","age":18}
print(info.keys())          #得到所有的键（列表）
print(info.values())        #得到所有的值（列表）
print(type(info.keys()))
print(info.items())         #得到所有的项，每个键值对是一个元组

#遍历所有的键
for key in info.keys():
    print(key)

#遍历所有的键值对
for key,value in info.items():
    print("key = %s,value = %s"%(key,value))
"""
#使用枚举函数同时获得列表的下标和元素
a = ["小明","小红","小李","小张"]
for i,j in enumerate(a):
    print(i+1,j)