我们得到了一个词典，其中键值对本身的值是一个列表。在本文中，我们将了解如何计算此列表中作为字典中的值显示的项目数。
与isinstance
印地语假设我们使用isinstance函数来查找字典的值是否为列表。然后，只要isinstance返回true，就增加一个count变量。
示例# defining the dictionary
Adict = {'Days': ["Mon","Tue","wed","Thu"],
'time': "2 pm",
'Subjects':["Phy","Chem","Maths","Bio"]
}
print("Given dictionary:\n",Adict)
count = 0
# using isinstance
for x in Adict:
if isinstance(Adict[x], list):
count += len(Adict[x])
print("The number of elements in lists: \n",count)
输出结果
运行上面的代码给我们以下结果-Given dictionary:
{'Days': ['Mon', 'Tue', 'wed', 'Thu'], 'time': '2 pm', 'Subjects': ['Phy', 'Chem', 'Maths', 'Bio']}
The number of elements in lists:
8
与items()
我们在字典的每个元素中循环使用哪个items()并应用isinstance函数来确定它是否为列表。
示例# defining the dictionary
Adict = {'Days': ["Mon","Tue","wed","Thu"],
'time': "2 pm",
'Subjects':["Phy","Chem","Maths","Bio"]
}
print("Given dictionary:\n",Adict)
count = 0
# using .items()
for key, value in Adict.items():
if isinstance(value, list):
count += len(value)
print("The number of elements in lists: \n",count)
输出结果
运行上面的代码给我们以下结果-Given dictionary:
{'Days': ['Mon', 'Tue', 'wed', 'Thu'], 'time': '2 pm', 'Subjects': ['Phy', 'Chem', 'Maths', 'Bio']}
The number of elements in lists:
8
用枚举
枚举功能还可以扩展并列出字典中的项目。我们应用实例来找出列出的值。
示例# defining the dictionary
Adict = {'Days': ["Mon","Tue","wed","Thu"],
'time': "2 pm",
'Subjects':["Phy","Chem","Maths","Bio"]
}
print("Given dictionary:\n",Adict)
count = 0
for x in enumerate(Adict.items()):
if isinstance(x[1][1], list):
count += len(x[1][1])
print(count)
print("The number of elements in lists: \n",count)
输出结果
运行上面的代码给我们以下结果-Given dictionary:
{'Days': ['Mon', 'Tue', 'wed', 'Thu'], 'time': '2 pm', 'Subjects': ['Phy', 'Chem', 'Maths', 'Bio']}
8
The number of elements in lists:
8