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Welcome back, I want to talk to you quickly about something called Matrix.

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And The Matrix is a way to describe 2D lists or multidimensional lists.

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What do I mean?

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Well, I can create a matrix and this is a name that I just made so I can call it whatever I want.

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But usually these are called matrix in programming.

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And it looks something like this, it's an array.

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With another array inside of it.

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So let's say, for example.

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I have one, two, three here.

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And then another array, one or less, two to four.

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And then another seven, eight, nine.

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What's happening here?

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Well, it's a two dimensional array.

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We have the main array.

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And then we have sub iRace, three arrays, to be exact.

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Now, why is this useful?

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And by the way, this is two dimensional, but we can have multiple ones.

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For example, we can have another array inside of this array.

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But why is this important?

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These type of mattresses come up a lot in topics like machine learning or image processing.

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For example, a computer doesn't really know what a photo of a dog is.

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The only thing it understands is zeros and ones.

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So a lot of photos, for example, let's say we had a very simple photograph of a giant X, maybe this

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letter X.

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Well, a computer can understand an image based on pixels on the screen, so maybe we can have zero

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one zero.

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One zero zero or sorry, one here, zero here and then one, and right now a computer can look at this.

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And if this represented, let's say, a tiny little pixel here or maybe a pixel here on my screen,

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the computer is going to say, oh, there's a one here.

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So that means I should make this green in this corner, then dark here, then green, then dark green,

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dark green, dark green.

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And a computer is able to draw, let's say, an X, and this is a simple example.

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And using matrices, we can do a lot of these heavy calculations.

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And that's how computers work underneath the hood when let's say, for example, it's trying to display

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something.

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But the reason I wanted to talk about this here is when you want to access a multi dimensional list,

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well, you would do something like this, let's say matrix.

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Access the first item.

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And the Matrix, which in this case will be this first array, because it's the first item and then

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let's say we want to access the zero, and here are let's change this to five.

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Well, how do square brackets again and just do zero one.

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So if I go.

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One here, and let's print that out.

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And I click run.

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I get five, so it's accessing the first item in the array, so it's going to look at the first Ottery

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grab the first item, which is right here, and then grab the second item in that array.

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So zero one, which is five.

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And you can keep doing this, if he had multidimensional arrays, you can keep adding, keep adding,

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keep adding.

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To access that information from an array or list, but remember in Python, we want to use the term

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list.

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I'll see you in the next one.

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Bye bye.