Sort python list of dictionaries by key if key exists
python, sorting
Solution
Check out `dict.get`:
featured = sorted(filesToWrite, key=lambda k: ("myKey" not in k, k.get("myKey", None)))
Output:
[{'foo': 'bar', 'myKey': 'one'}, {'foo': 'bar', 'myKey': 'two'}, {'yourKey': 'three', 'foo': 'bar'}]
The magic happens in the key:
("myKey" in k, k.get("myKey", None)
Which is a two item tuple, like:
(True, "one")
Where the first element is True/False depending on whether or not the key is missing (True comes after False hence the `not`), and the second element is the value of said key, if it exists. If not, `None`. (that argument can be skipped, but I included it to be explicit)
Problem
I have a list of dictionaries like this: ``` [{"foo" : "bar", "myKey" : "one"}, {"foo" : "bar", "myKey" : "two"}, {"foo" : "bar", "yourKey" : "three"}] ``` I'd like to sort it by a key in the dictionary if it exists. ``` featured = sorted(filesToWrite, key=lambda k: k["myKey"]) ``` This doesn't work if `"myKey"` doesn't exist. EDIT: If `myKey` doesn't exist in the dictionary, I'd like it to appear at the end of the list. I could loop through the list manually and do it myself but I'm sure there is a pythonic way to accomplish my goal without doing all that.