Python for Absolute Beginners Transcripts
Chapter: Course conclusion
Lecture: Review: Data structures
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The next things that we talked about were data structures. And we had started with code that looked like this, on the left.
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And remember, our dog, was not impressed. Not even a little bit. Because that is some bad code that is hard to maintain hard to evolve
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and much, much more. We went into all the details there. We saw though, that important data structures that are built into Python
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lists and dictionaries in particular allow us to build much cleaner code. And what's really pretty amazing is we made our game way more complicated
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by just changing the definition of that dictionary or even the JSON file that was loaded into a dictionary
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without even touching the code that operated a game. I mean that's really, really impressive. So, couple things we can do with dictionaries.
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We can create them. We can create them with their name their class name, like this. Or we can create them with these curly braces, like so.
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We can even create them pre-populated like here we're creating a dictionary that has 2 wins for Bill, 7 for Zoe, and 4 for Michael.
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That's equivalent to creating it like this as well where you say, as a string key: value. key: value. So on. If we want to get a value back out, like
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how many times has Zoe won? We're going to have a key. And usually this is not hard coded like, quote Zoe.
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It's some variable that you've gotten its value assigned to. And then we can say well whoever's value is in name
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they have however many wins we'd get out. Now remember, we must have that value as a key or it's going to crash. But for Zoe we have her, so it's says
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wins by Zoe are seven. If we don't have Zoe in the dictionary this is going to throw a key error and crash and we'll be out of luck.
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Our program's going to stop. Not going to be impressive. So what we can do is we can attempt to get the value out of the dictionary with a .Get
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instead of the square brackets and pass the key. What we get back is either a value for the wins
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or none in this case if there's no value for that name. In this case, we're actually leveraging the truthiness of wins.
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If it comes back as None, going to be False. If it comes back as 0, also no wins. Going to be false, we'll say no games played.
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Otherwise, it's going to come back and say there's one, two, three, five wins, so on. Dictionaries also list those are the two most important
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data structures that we worked with throughout this course.