如果不存在，Python将更新dict中的键 [英] Python update a key in dict if it doesn't exist

问题描述

如果key不位于dict.keys()中，我想向dict中插入一个键-值对. 基本上我可以做到:

I want to insert a key-value pair into dict if key not in dict.keys(). Basically I could do it with:

if key not in d.keys():
    d[key] = value

但是有更好的方法吗?还是该问题的pythonic解决方案是什么?

But is there a better way? Or what's the pythonic solution to this problem?

推荐答案

您不需要致电d.keys()，所以

if key not in d:
    d[key] = value

就足够了.没有更清晰，更易读的方法.

is enough. There is no clearer, more readable method.

您可以再次使用dict.get()更新，如果键已经存在，它将返回一个现有值:

You could update again with dict.get(), which would return an existing value if the key is already present:

d[key] = d.get(key, value)

但我强烈建议您反对；这是代码打高尔夫球，妨碍了维护和可读性.

but I strongly recommend against this; this is code golfing, hindering maintenance and readability.

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