从python中的字典列表中查找特定值

I have the following data in my list of dictionary:

我在字典列表中有以下数据：

data = [{'I-versicolor': 0, 'Sepal_Length': '7.9', 'I-setosa': 0, 'I-virginica': 1},
{'I-versicolor': 0, 'I-setosa': 1, 'I-virginica': 0, 'Sepal_Width': '4.2'},
{'I-versicolor': 2, 'Petal_Length': '3.5', 'I-setosa': 0, 'I-virginica': 0},
{'I-versicolor': 1.2, 'Petal_Width': '1.2', 'I-setosa': 0, 'I-virginica': 0}]

And to get a list based upon a key and value I am using the following:

为了获得基于键和值的列表，我使用以下内容：

next((item for item in data if item["Sepal_Length"] == "7.9"))

However, all the dictionary doesn't contain the key Sepal_Length, I am getting :

但是，所有字典都不包含密钥Sepal_Length，我得到：

KeyError: 'Sepal_Length'

How can i solve this?

我怎么解决这个问题？

1 个解决方案

#1

You can use dict.get to get the value:

您可以使用dict.get来获取值：

next((item for item in data if item.get("Sepal_Length") == "7.9"))

dict.get is like dict.__getitem__ except that it returns None (or some other default value if provided) if the key is not present.

dict.get就像dict .__ getitem__，除非它返回None（如果提供了其他默认值），如果该键不存在。

Just as a bonus, you don't actually need the extra parenthesis here around the generator expression:

作为奖励，您实际上并不需要围绕生成器表达式的额外括号：

# Look mom, no extra parenthesis!  :-)
next(item for item in data if item.get("Sepal_Length") == "7.9")

but they help if you want to specify a default:

但如果要指定默认值，它们会有所帮助：

next((item for item in data if item.get("Sepal_Length") == "7.9"), default)

#1