python中创建字典、字典的访问

python中创建字典、字典的访问

1、

>>> test1 = {"aaa":111,"bbb":222,"ccc":333}
>>> test1
{'aaa': 111, 'bbb': 222, 'ccc': 333}
>>> type(test1)
<class 'dict'>
>>> 

2、

>>> test2 = dict((("aaa",111),("bbb",222),("ccc",333)))
>>> test2
{'aaa': 111, 'bbb': 222, 'ccc': 333}
>>> type(test2)
<class 'dict'>

3、

>>> test3 = dict(aaa=100,bbb=200,ccc=300)
>>> test3
{'aaa': 100, 'bbb': 200, 'ccc': 300}
>>> type(test3)
<class 'dict'>
>>> 

4、

>>> a = ["aaa","bbb","ccc"]
>>> b = [100,200,300]
>>> test4 = dict(zip(a,b))
>>> test4
{'aaa': 100, 'bbb': 200, 'ccc': 300}
>>> type(test4)
<class 'dict'>

5、

>>> test5={}
>>> test5["aaa"] = 100
>>> test5["bbb"] = 200
>>> test5["ccc"] = 300
>>> test5
{'aaa': 100, 'bbb': 200, 'ccc': 300}
>>> type(test5)
<class 'dict'>

6、如果键重名，前面的将被后面的覆盖

>>> test1 = {"aaa":100,"bbb":200,"ccc":300,"aaa":400}
>>> test1
{'aaa': 400, 'bbb': 200, 'ccc': 300}

7、键、键值、键值对的访问

>>> test1
{'aaa': 400, 'bbb': 200, 'ccc': 300}
>>> test1["aaa"]
400
>>> for i in test1:
    print(i)

    
aaa
bbb
ccc
>>> for i in test1:
    print(test1[i])

    
400
200
300
>>> for i in test1:
    print(i,":", test1[i])

    
aaa : 400
bbb : 200
ccc : 300