本文介绍了检查字典列表中是否已经存在值?的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
我有一个Python字典列表,如下所示:
I've got a Python list of dictionaries, as follows:
a = [ {'main_color': 'red', 'second_color':'blue'}, {'main_color': 'yellow', 'second_color':'green'}, {'main_color': 'yellow', 'second_color':'blue'}, ]我想检查列表中是否已存在具有特定键/值的字典,如下所示:
I'd like to check whether a dictionary with a particular key/value already exists in the list, as follows:
// is a dict with 'main_color'='red' in the list already? // if not: add item推荐答案
这里是一种方法:
if not any(d['main_color'] == 'red' for d in a): # does not exist括号中的部分是一个生成器表达式,对于具有要查找的键值对的每个词典,返回True,否则返回False.
The part in parentheses is a generator expression that returns True for each dictionary that has the key-value pair you are looking for, otherwise False.
如果密钥也可能丢失,则上面的代码可以为您提供KeyError.您可以使用get并提供默认值来解决此问题.
If the key could also be missing the above code can give you a KeyError. You can fix this by using get and providing a default value.
if not any(d.get('main_color', None) == 'red' for d in a): # does not exist更多推荐
检查字典列表中是否已经存在值?
发布评论