如何查字典？

Question

我是 Python 字典的新手。我正在制作一个简单的程序，它有一个字典，其中包含四个名称作为键，各自的年龄作为值。我想做的是，如果用户输入一个名字，程序会检查它是否在字典中，如果是，它应该显示有关该名字的信息。

这是我目前拥有的：

def main():
    people = {
        "Austin" : 25,
        "Martin" : 30,
        "Fred" : 21,
        "Saul" : 50,
    }

    entry = input("Write the name of the person whose age you'd like to know, or write 'ALL' to see all names and ages: ")
    if entry == "ALL":
        for key, value in people.items():
            print ("Name: " + key)
            print ("Age: " + str(value) + "\n")
    elif people.insert(entry) == True:
                print ("It works")

main()

我尝试使用 .index() 搜索字典，因为我知道它在列表中使用，但没有成功。我也尝试检查 this post 但我发现它没有用。

我想知道是否有任何函数可以做到这一点。

Answer 1

足够简单

if entry in people:
    print ("Name: " + entry)
    print ("Age: " + str(people[entry]) + "\n")

Answer 2

如果您想知道 key 是否是 people 中的键，您可以简单地使用表达式 key in people，如：

if key in people:

并测试它是否不是people中的一个键：

if key not in people:

Answer 3

您可以直接引用这些值。例如：

>>> people = {
... "Austun": 25,
... "Martin": 30}
>>> people["Austun"]

或者您可以使用 people.get(<Some Person>, <value if not found>).

Answer 4

Python 也支持枚举来遍历字典。

for index, key in enumerate(people):
    print index, key, people[key]

Answer 5

你可以这样做：

#!/usr/bin/env python3    

people = {
    'guilherme': 20,
    'spike': 5
}

entry = input("Write the name of the person whose age you'd like to know, or write 'ALL' to see all names and ages: ")

if entry == 'ALL':
    for key in people.keys():
        print ('Name: {} Age: {}'.format(key, people[key]))

if entry in people:
    print ('{} has {} years old.'.format(entry, people[entry]))
else:
    # you can to create a new registry or show error warning message here.
    print('Not found {}.'.format(entry))

Answer 6

在此处的所有答案中，为什么不呢：

try:
    age = people[person_name]
except KeyError:
    print('{0} is not in dictionary.'.format(person_name))

测试某些内容是否在 Python 中的字典中的规范方法是尝试访问它并处理失败 -- It is easier to ask for forgiveness than permission (EAFP).

Answer 7

一种可能的解决方案：

people = {"Austin" : 25,"Martin" : 30,"Fred" : 21,"Saul" : 50,}

entry =raw_input ("Write the name of the person whose age you'd like 
to know, or write 'ALL' to see all names and ages: ")

if entry == 'ALL':

    for key in people.keys():
        print(people[key])

else:

    if entry in people:
        print(people[entry])

如何查字典？

How to search through dictionaries?

python

search

dictionary