All we do is call sort on the list, for in-place sorting, or the built in function sorted for not modifying the original list and returning a new sorted list. It's calling a version of mergesort on the list. The return value is 0 for equal to, 1 for greater than, and -1 for python list to tuple than the compared value. We'll use this information later to make our own objects sortable. What about tuples, you say. Sorting a Python Tuple the Simple Way Since tuples are arrays that you cannot modify, they don't have an in-place sort function that can be called directly on them. They must always use the sorted function to return a sorted list. Okay, now let's see how to sort something a little more complicated. Sorting a List of Lists or Tuples This is a little more complicated, but still pretty easy, so don't fret. Both the sorted function and the sort function take in a keyword argument called key. What key does is it provides a way to specify a function that returns what you would like your items sorted by. Let me illustrate, for your superb eyes only, the key keyword argument. Note that you could have used the sort function as well, but I personally like the sorted function better, so I'll be using that in further examples. That's what gets passed into the getKey function every time the sorted needs a value. The exact same solution can be applied to a tuple of tuples, so I'm not going to go there, as that would just be redundant. It would also waste more of those digital trees that make this beautiful digital paper. Sorting a List or Tuple of Custom Python Objects Here's a custom object that I created: self. In more complex terms, it tells the interpreter how to display the object when it is printed to the screen. So, we tell Python to represent the object by it's class name, name, and number. Now we can actually tell that it sorted properly. But there's a little bit of a problem. It's just nit-picking, but I don't want to have to type that key keyword every time I call sorted. So, how do I do that. Let's put it into action. Let's redefine our object one more time like this: return self. What this does is tell Python to compare the value of the current object to another object in the list to see how it compares. Please note that all of the above also applies to tuples of the custom object. But I like to save my digital trees, as you know. Sorting a Heterogeneous List of Custom Python Objects Alright. Since Python is a dynamic language, it doesn't so much care about what objects we throw into lists. They can all be the same type, or they can all be different. So let's define another different object to use with python list to tuple Custom object. Pretty straight forward, but not python list to tuple straight forward as some might guess. Still, Python makes it pretty easy with its built in sorted function. For more sorting ideas, head over to. You could also check out for instructions on how to sort with lambda functions. One step closer to becoming the world's Python master.
