Python Tutorial : Meet the Tuples

Key Takeaways

the next container top we want to learn about is the tuple tuples are widely used internally and many of the systems that we depend upon like databases tuples are very much like lists they hold data in the order we supply it and we can access the elements inside a tuple with an index however the similarities and their tuples are easier to process and more memory efficient than lists tuples are also immutable which means that we can't add or remove elements from them this is powerful because we can use them to ensure that our data is not altered we can create tuples by pairing up elements finally we can use something called tuple unpacking to expand a tuple into named variables that represent each element of the tuple let's explore these features often we'll have lists where we want to match up elements into pairs and the zip function enables us to do that here I've got a list for the most popular cookies in the US and India and I want to build a list of pairs by the popularity rank of the cookie in each country I'll pass them to the zip function then I can print the result of my zip and you can see I have what looks like a list of tuples it's really an iterator but that's for a different course notice that the tuples use the parentheses as their object representation now let's look at how we can use unpacking with a tuple tuple unpacking also sometimes called tuple expansion allows us to assign the elements of a tuple to name variables for later use this syntax allows us to create more readable less error-prone code here I have a tuple containing the top-ranked cookie from both countries and I want to store them as US num1 and i in num1 so that i can print them by the name I start by putting both variables as the target of an assignment statement separated by a comma then I assign the first tuple and I'll talk pairs lists to them let's look at another great use case for tuple unpacking for me the place I use to pool unpacking the most is when working with loops we can use two pond packing when declaring the for loop to separate a list of tuples into their elements as we loop over them this sounds a bit strange but let's take a look at it here I'm building a for loop that uses tuple unpacking when iterating over the top pairs list it splits each tuple in the list into its Indian and US cookie elements we then use each of these variables to print the cookies in order another use of tip on packing helps us keep track of which element in the iterable or lists we are currently working on often we want to know what the index is of an element in the interval the enumerate function enables us to do that by creating tuples where the first element of the tuple is the index of the element in the original list and then the element itself is the second we can use this to track rankings in our data or skip elements were not interested in here I'm going to enumerate our top payers lists and split that into the resulting tuple into index and item I can also use tuple unpacking on the atom to get all three components separately this can be exceptionally powerful let's look at a bit of responsibility that comes with this power when we are creating tuples we can make them with a zip or enumerate or use the parentheses as shown here however the real magic for creating a two point Python is the comma if we accidentally in an assignment line with a comma we can create a tuple and this can have some very undesirable side effects further down in our code so keep this in mind if you get a tuple where you don't expect it