python学习日记之数据类型（3）

一.元组Tuple

不可变的列表称之为元组.语法与列表一样。

tuple1=(1,2,3)
tuple1[0]=6

结果:

TypeError: 'tuple' object does not support item assignment

根据以上代码可以看出来，元组中的元素是不能够被修改的。但是可以通过新定义元组关联到旧的元组变量名。

tuple1=(1,2,3)
tuple1=(6,2,3)
print(tuple1)

结果:

(6, 2, 3)

二.字典 Dictionary

python中的字典类似于java中的map。但是它的格式跟json好像...也可以字典里面 嵌套字典/列表。

dist={"class":"2-5","student":[{"name":"xiaohua","age":23},{"name":"xiaohuang","age":"28"}]}

1.增

dist={"class":"2-5","student":[{"name":"xiaohua","age":23},{"name":"xiaohuang","age":"28"}]}
dist["lead"]="teacher_wang"
print(dist)

结果:

{
    "class":"2-5",
    "student":[
        {
            "name":"xiaohua",
            "age":23
        },
        {
            "name":"xiaohuang",
            "age":"28"
        }
    ],
    "lead":"teacher_wang"
}

2.删

dist={"class":"2-5","student":[{"name":"xiaohua","age":23},{"name":"xiaohuang","age":"28"}]}

dist["lead"]="teacher_wang"
#根据键删除
del dist["lead"]
print(dist)

3.遍历

遍历字典中的所有键，值

dist={"class":"2-5","student":[{"name":"xiaohua","age":23},{"name":"xiaohuang","age":"28"}]}
for key,value in dist.items():
    print(f"key:{key}")
    print(f"value:{value}")

结果:

key:class
value:2-5
key:student
value:[{'name': 'xiaohua', 'age': 23}, {'name': 'xiaohuang', 'age': '28'}]

遍历字典中的所有键

for key in dist.keys():
    print(f"key:{key}")

遍历字典中的所有值

for v in dist.values():
    print(f"value:{v}")