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Time for more interesting projections but now projections that work with arrays or are related to arrays.

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I'll stick to my friends dataset for this,

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so let's quickly peek into it and let's work with the exam scores

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now. Let's say you only want to output the first value of that array instead of all the exam scores,

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so it's time for a projection of course.

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So let's add a project phase here and in projection,

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I'm not interested in the ID but I'm very interested in my exam score and I'll name it exam score

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and not scores because I'll only output 1.

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Now to output one, there is a helpful operator and this is of course the main thing I want to show you here,

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the slice operator. The slice operator allows you to get back the slice of an array,

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so how does the slice operator work?

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It takes an array itself,

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the first value is the array you want to slice and you could hardcode an array in here, that would be

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possible but of course I will point onto a field with $examscores,

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so I'm essentially pointing at this field. And now I only want to get the first element and for this, I

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pass one as the second argument because slice takes in its basic form two arguments, the array and the

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amount of elements you want to get out of the array

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seen from the start.

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So here with this, if I take this command and I execute it, you see now I only have my exam score or one

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exam score per user and that is the first exam score, we can validate this with the last user,

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the first one should be difficulty three and score 75.1

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and that is the case here to. Now

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sometimes you want to you have let's say the last two, for this you can actually use a negative value

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here, -2 because then we'll start at the end,

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if I now paste this in, you see I get the last two scores per user,

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so this also works or you want to get one element but starting at the second element, then you could

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also use a different syntax with three elements in the array,

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two and then one. This means start at position two and then give me one element and if I now execute

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this, you see I get back some exam scores and which scores added,

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well these are the last scores because indexes are zero based,

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so if I start at two, I will skip 0 and 1,

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so the first two elements, I start at the last element

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therefore and then I take one element,

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so I get back the last element.

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So these are the different ways of using slice and that can be very helpful for transforming an array

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or getting just the values of an array

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you need.