python字典基礎知識

#字典 key不允許出現重複，value可以出現重複 #使用大括號{}創建 dict1 = {} dict2 = {"name":"李","age":"23"} #利用函數dict創建字典 dict3 =dict(name="李暢",sex="男") print(dict3) #dict.formkeys創建鍵值 dict4 = dict.fromkeys(['name','sex','hiredate','grade']) print(dict4) #字典的取值 employee = dict(name='王峯',sex='男',hiredate='1997-10-20',grade='A' ,job='銷售',salry='1000') print(employee) print(employee['name']) job = employee.get('job') print(job) print(employee.get('dept','其他部門')) #判斷key是否在字典中 print('name' in employee) #遍歷字典 for key in employee:#把key以此取出來 v=employee[key] print(key,end="") print(v) for key,value in employee.items(): print(key,value) #字典的更新操作 employee['name'] = '李暢' print(employee) #多個key直進行更新 employee.update(salry = 12000,job='信息') print(employee) #刪除指定kv employee.pop('salry') print(employee) #刪除末端kv employee.popitem() print(employee) #清空字典 employee.clear() print(employee) #爲字典設置默認值 emp1 = {'name':'jacky','grade':'B'} emp2 = {'name':'lily',} emp2.setdefault('grade','C')#如果不存在則設置，如果存在則不管 # if 'grade' not in emp2: # emp2['grade'] = 'C' print(emp2) #獲取字典的視圖 #獲取所有的鍵 ks=employee.keys() print(ks) vs = employee.values() print(vs) its = employee.items() #修改視圖後字典也會變化 print(its) #用字典字符串的格式化 emp_str = "姓名：%(name)s,評級：%(grade)s"%emp1#其中name是鍵， print(emp_str) #新版本字典格式化 emp_str = "姓名：{name},評級：{grade}".format_map(emp1) print(emp_str) #字典的散列值hash