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)
print(tup1[-1])
print(tup1) #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 = 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)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)
来源:https://www.cnblogs.com/he-cheng/p/17126323.html
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