Python3学习笔记:字典 心已赠人 2022-05-22 06:41 195阅读 0赞 Python中的字典用于存储 key-value(键值对)类型数据。 # 字典的表现形式 # if __name__ == '__main__': dict1={1:"a",2:23,4:1+5j} dict2={"1":"j","2":2} dict3={} dict4={"1+2j":4,"4-5j":5} dict5={"1+7j":4,"2":5,1:"sdfsdf"} dict6={1:dict1,2:dict2,3:dict3,4:dict4,5:dict5} print("dict1=",dict1) print("dict2=",dict2) print("dict3=",dict3) print("dict4=",dict4) print("dict5=",dict5) print("dict6=",dict6) 相应输出为 dict1= {1: 'a', 2: 23, 4: (1+5j)} dict2= {'1': 'j', '2': 2} dict3= {} dict4= {'1+2j': 4, '4-5j': 5} dict5= {'1+7j': 4, '2': 5, 1: 'sdfsdf'} dict6= {1: {1: 'a', 2: 23, 4: (1+5j)}, 2: {'1': 'j', '2': 2}, 3: {}, 4: {'1+2j': 4, '4-5j': 5}, 5: {'1+7j': 4, '2': 5, 1: 'sdfsdf'}} (1)字典可以为空,可以嵌套 (2)key可以为任意数据类型,但必须唯一 # 字典元素的访问 # print("dict1[1] = ", dict1[1]) print("dict2['1'] =", dict2["1"]) print("dict4.get['1+2j'] = ",dict4.get("1+2j")) 相应输出为 dict1(1) = a dict2['1'] = j dict4.get['1+2j'] = 4 共有两种访问方式 (1)dictname【key】 (2)dictname.get(key) # 字典元素的修改 # print("dict1[1] = ",dict1[1]) dict1[1]=0 print("dict1[1] = ",dict1[1]) print("dict5['1+7j']= ",dict5["1+7j"]) dict5["1+7j"]=2 print("dict5['1+7j']= ",dict5["1+7j"]) 相应输出为 dict1[1] = a dict1[1] = 0 dict5['1+7j']= 4 dict5['1+7j']= 2 需要指出的是,get方法不能用于修改。即不能使用dict1.get(1)=0 # 字典元素的删除 # print("dict1=",dict1) del dict1[1] print("dict1=",dict1) del dict1 # print("dict1=",dict1) print("dict6=",dict6) dict6.pop(1) print("dict6=",dict6) dict6.clear() print("dict6=",dict6) 相应输出为 # # dict1= {1: 0, 2: 23, 4: (1+5j)} dict1= {2: 23, 4: (1+5j)} dict6= {1: {2: 23, 4: (1+5j)}, 2: {'1': 'j', '2': 2}, 3: {}, 4: {'1+2j': 4, '4-5j': 5}, 5: {'1+7j': 2, '2': 5, 1: 'sdfsdf'}} dict6= {2: {'1': 'j', '2': 2}, 3: {}, 4: {'1+2j': 4, '4-5j': 5}, 5: {'1+7j': 2, '2': 5, 1: 'sdfsdf'}} dict6= {} 共有四种删除方式 (1)del dictname\[key\] (2)dictname.pop\[key\] (3)del dictname (4)dictname.clean() 需要指定的是,del字典后,该字典变量就不存在了,因此,不能再次访问。 字典其它工具方法 print("dict5 length = ", len(dict5)) #字典长度 print("dict5 keys =",dict5.keys()) #字典key集合 print("dict5 values = ",dict5.values()) #字典值集合 print("dict5 items =", dict5.items()) #字典item集合 相应输出为 dict5 length = 3 dict5 keys = dict_keys(['1+7j', '2', 1]) dict5 values = dict_values([2, 5, 'sdfsdf']) dict5 items = dict_items([('1+7j', 2), ('2', 5), (1, 'sdfsdf')])
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