Python 如何通过字典进行搜索？
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How to search through dictionaries?
提问by Fede Couti
I'm new to Python dictionaries. I'm making a simple program that has a dictionary that includes four names as keys and the respective ages as values. What I'm trying to do is that if the user enters the a name, the program checks if it's in the dictionary and if it is, it should show the information about that name.
我是 Python 词典的新手。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和相应的年龄作为值。我想要做的是，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。
This is what I have so far:
这是我到目前为止：
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()
I tried searching through the dictionary using .index()as I know it's used in lists but it didn't work. I also tried checking this postbut I didn't find it useful.
我尝试在字典中搜索，.index()因为我知道它在列表中使用过，但没有用。我也试过检查这篇文章，但我发现它没有用。
I need to know if there is any function that can do this.
我需要知道是否有任何功能可以做到这一点。
采纳答案by Scott Hunter
If you want to know if keyis a key in people, you can simple use the expression key in people, as in:
如果你想知道 ifkey是一个键people，你可以简单地使用表达式key in people，如：
if key in people:
And to test if it is nota key in people:
并测试它是否不是一个键people：
if key not in people:
回答by Laurent Jalbert Simard
Simple enough
足够简单
if entry in people:
print ("Name: " + entry)
print ("Age: " + str(people[entry]) + "\n")
回答by Games Brainiac
You can reference the values directly. For example:
您可以直接引用这些值。例如：
>>> people = {
... "Austun": 25,
... "Martin": 30}
>>> people["Austun"]
Or you can use people.get(<Some Person>, <value if not found>).
或者你可以使用people.get(<Some Person>, <value if not found>).
回答by Cui Heng
Python also support enumerate to loop over the dict.
Python 还支持 enumerate 循环遍历 dict。
for index, key in enumerate(people):
print index, key, people[key]
回答by Guilherme Arthur de Carvalho
You can make this:
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))
回答by D.Shawley
Of all of the answers here, why not:
在这里的所有答案中，为什么不：
try:
age = people[person_name]
except KeyError:
print('{0} is not in dictionary.'.format(person_name))
The canonical way to test if something is in a dictionary in Python is to try to access it and handle the failure -- It is easier to ask for forgiveness than permission (EAFP).
测试某些东西是否在 Python 字典中的规范方法是尝试访问它并处理失败——请求宽恕比请求许可 (EAFP) 更容易。
回答by Muhammad Umar
One possible solution:
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])
