1.字典以键值对组成,包含在{}中,字典的键必须为hashable,即不可变(字符串、元组、数字),并且唯一;值可以是任何类型
# dict1 = {[1]: 1} # 报错:TypeError: unhashable type: 'list'
# dict1 = {{1}: 1} # 报错:TypeError: unhashable type: 'set'
dict1 = {(1,): 1}
print(dict1) # {(1,): 1}
dict1 = {"12": 122}
print(dict1) # {'12': 122}
dict1 = {1: 12}
print(dict1) # {1: 12}
2.字典的创建有多种,以下几种都等同
dict1 = dict(one=1, two=2)
print(dict1) # {'one': 1, 'two': 2}
dict2={"one":1,"two":2}
print(dict2) # {'one': 1, 'two': 2}
dict3=dict(zip(["one","two"],[1,2]))
print(dict3) # {'one': 1, 'two': 2}
dict4=dict( (("one",1),("two",2)) )
print(dict4) # {'one': 1, 'two': 2}
dict5=dict( [("one",1),("two",2)] )
print(dict4) # {'one': 1, 'two': 2}
dict6=dict({"one":1,"two":2})
print(dict6) # {'one': 1, 'two': 2}
print(dict1==dict2==dict3==dict4==dict5==dict6) # True
3.键用数字的时候,像1和1.0、1.00都是相同的,可以用来索引同一个字典条目,如果相同的键出现多次,则以最后的值为准
dict1 = {1: 12}
print(dict1) # {1: 12}
dict1 = {1: 12, 1.0: 33}
print(dict1) # {1: 33}
dict1 = {1: 12, 1.0: 33,1.00:666}
print(dict1) # {1: 666}
4.len(dict):