Using "get()" to Return a Default Value from a Python Dict

hey there is Daniel with another quick Python tip so many of you are probably familiar with pythons dictionaries and I want to show you a quick tip today where we talk about the get method that's available on any Python dictionary and its default argument because in a lot of situations especially if you're dealing with text processing can be really helpful so I tried coming up with a simple example to show how how you can use the get method and I came up with this example where we have a dictionary that's called name for user ID where it basically maps from a integer user ID to the user's name right and you can imagine this comes from a database or whatever like it's it's it could be a real data structure that you have somewhere in your script or your Python application and so now what we want to do is we want to write a function that we're gonna call greeting that just takes a user ID and what we want that function to do is to return a greeting for that user and probably the simplest way we could think of implementing that which is be you know some kind of format string where we say hi and then substitute the user's name and we just go name for user ID and look up the name based on the user ID right so if we do this and let's just actually define that and then play with it for a bit and we pass in a valid user ID to work fine however if we're passing in an invalid ID this is going to blow up so now it would be really interesting or really good for us for that function to actually return something useful if the user ID is not available and so you might think you know the first thing we could do here is pull we're just going to check if the user ID is actually in the dictionary so it should say okay if user ID in name for user ID then we're going to return we have and if not we're just going to return kind of sensible default right okay so now we still get the same behavior if I put in a valid user ID I get my high Ellis I put in an invalid user ID I get my hi there which it's kind of what I want okay so so this would work so now the challenge with this implementation that we have is that it could be a little bit more pretty so the first thing is that it's it's kind of not good style to do a membership chick here so a little bit more pythonic option would be to actually just try and grab the the name for the user ID and if it fails we would erase an exception or kind of catch it would race and exception itself we would catch the exception and it just returned to default so a better implementation could look like this where we would have this triblock and we just say okay just try to do this and if we get a key error we'll just return hi there and now this works the way we expect it to work but this could still be a little bit shorter okay so there's actually a better way we can do this because most of this is actually built into Python because it's such a common thing so I hinted at this in the beginning every dictionary in Python has a get method on it and you can see the the doc string forget here and the way it works is that you can pass a key to it you know it's it's so instead of doing instead of doing this where the key would be the key would be the user ID we can use the get method and pass the same key and we get the same result okay so that seems pretty useless right like why not use the shorthand square bracket syntax for that so now the cool thing is that you can pass a default that will get returned if if the key could not be found right so what we can do now is we can specify a default let's say there and then if the idea is found we get the value for that key but if we pass in an invalid ID or you know when I would trigger a key error we get the default so with that get method it becomes a lot easier to define our greeting greeting method we could just say okay return hi and then we do the string substitution whoops we'll do the string substitution and then we're just going to say name for user ID get passing the ID and we're going to make the default there right now when we run greeting we pass a valid ID it works as expected when we pass an invalid ID we get our expected result and so now this is really short makes it uses just a standard Python feature we don't have to deal with either doing a membership check or actually writing out that exception block so it's really nice and clean everyone's gonna understand it because it's a standard Python standard library feature and for that reason I think this is probably the best implementation for this little example cool I hope you enjoyed that and if you want more and then feel free to subscribe or check out my blog