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[MUSIC PLAYING]

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SPEAKER: Well, hello, one and all,
and welcome to our short on vectors.

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We'll take a look at how we can
use these things called vectors

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to store information and
also how to quickly build up

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vectors for use in R. Now, vectors
are this way of storing data that

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has all the same type, or we might
say in R, the same storage mode,

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for instance, all numbers
or all character strings.

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And they're really handy to build
up all kinds of other structures.

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So we'll focus on them today
and see if we can actually

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quickly make a lot of them
using functions built into R.

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So let's say I want to have
a vector here of words.

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And to make a new vector, I can
actually use this function called c(),

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where c() stands for Combine.

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This is a pretty key idea with vectors.

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I'm combining different individual
pieces of data into one vector.

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So here, I might have a vector of words,
like "It's", "a", "beautiful", "day",

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just like this.

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And I can store it, let's say, inside
of this object that I'll call words.

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And I can run this on line 1.

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And we'll see that it has been run
down in my R console down below.

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So if I want to see what's
inside of this words vector,

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I can simply type "words"
and run that line.

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And I'll see that I have
down below those four words--

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"It's" "a" "beautiful" "day."

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And again, this works
because this vector

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is created from individual pieces of
data that are all of the same type,

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in this case, all character strings.

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So c()-- great function to get to
know to build up vectors from scratch.

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But if you want to make other kinds of
vectors, if you want to manipulate them,

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it's worth thinking about
other functions that

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can help you do so pretty quickly.

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Let's say I wanted to have this vector,
"It's", "a", "beautiful", "day".

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But I want to repeat these words,
these four words, multiple times,

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like "It's" "a" "beautiful" "day",
"It's" "a" "beautiful" "day",

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"It's" "a" "beautiful" "day."

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I can actually do that using a function,
one called rep() where rep() stands

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for Repeat.

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And rep() can actually take as input a
vector and very quickly make for me some

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new vector based on that old vector.

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Let's try this out.

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The first argument to rep() is the
vector to begin with, so in this case,

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words.

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Or it could even be a single value.

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And here, one of the arguments
to rep() is one called times.

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So I can say, times = 2 here.

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And this will actually take my vector,
"It's", "a", "beautiful", "day",

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and give me a new vector with this,
"It's", "a", "beautiful", "day",

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repeated two times.

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I'll try running this here.

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And we'll see down below that I
get "It's" "a" "beautiful" "day",

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"It's" "a" "beautiful" "day".

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Pretty good.

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I could even do times = 3.

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And now I'll get that repeated
three times down below as well.

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So rep() good for repeating
things some number of times.

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But it turns out rep() also has
another argument, one called each.

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So notice how when I used times,
this took my vector as it is--

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"It's", "a", "beautiful", "day"-- and
repeated these values in that same order

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two or three different times.

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Well, if I use each, that will actually
look at every individual element I have

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in my vector, like "It's", "a",
"beautiful", "day," individually now,

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and repeat each of those two times.

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So let's see what happens here.

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I'll run this.

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And I'll get "It's" "It's" "a" "a"
"beautiful" "beautiful" "day" "day".

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So less of a utility here,
but you could imagine

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this being useful if you want to
transform a vector where every element

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you have might be repeated
each some number of times.

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So rep() a good tool to have in your
toolkit when working with vectors like

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these.

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Let's think of other
kinds of vectors, though.

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So this is here a character vector, one
that is filled with character strings.

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But, of course, vectors can
also be composed of numbers.

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So let me clear my console.

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And let's try making a new
vector, one called numbers.

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And I'll, just for simplicity, make this
a vector of 1, 2, 3, 4, 5, 6, 7, 8, 9,

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and 10.

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So this is my vector of
numbers 1 through 10.

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If I run line 1 to assign this vector
to the object numbers and type "numbers"

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down below, we'll all see that
vector down below as well.

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So c() again coming in handy when
I want to make, in this case,

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a vector of some numbers.

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But you could imagine it's getting
pretty tiring pretty quickly

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if I were to enter in beyond
just 10, like 100 or 200 or so.

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And I wanted 1, 2, 3, all
the way up to some number.

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So thankfully, R comes with the ability
to use what's called this colon here,

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which will give me a vector of numbers,
starting with the first one, inclusive,

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and ending with the last one, inclusive,
and going up in ascending order one

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number at a time.

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So here, if I run line
1 and line 3, I'll

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get the same result but
with much fewer lines--

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well, much less typing, let's say.

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I could even do this.

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I believe I could do without the c().

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And I could do numbers 1
through 10, and same thing here.

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So 1:10 actually creates
the vector for me.

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I don't need c() to do that
in this particular case.

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Now, what else could we do when it
comes to things like these sequences?

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You might often want to create
some sequence of numbers.

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But you might not always want it to be
in ascending order one number at a time.

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So there is a function to be
aware of, one called seq(),

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which stands for sequence, and allows
you to construct numeric vectors

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by specifying some start point, some
end point, and some, let's say--

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what do you call it-- maybe
an increase along the way.

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So here, why don't we try this from
argument to seq() and start with 1,

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and the "to" argument to
seq() and start with 10.

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And this will by default give me
the same thing we said before,

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a sequence of numbers 1 through 10.

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I'll hit Enter on this, Enter on this.

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And now we'll see here that I get
1, 2, 3, 4, 5, 6, 7, 8, 9, 10,

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so sequence then doing the
same work we had with 1:10.

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But let's say I want to get a
little more fancy with this.

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I certainly can.

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Seq() actually has as an argument
as well an argument called "by."

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And by specifies a number to
increase by as we go through

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and create our sequence.

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So to be clear, we would start
at 1 and then jump up two to 3

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and then jump up two to 5, all the way
until we get to 10 exactly or above 10.

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So let's see what happens here.

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I'll run numbers.

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I'll run numbers and then numbers again.

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And here, we see 1, 3, 5, 7, 9, so now
increasing, we'll see, by 2 each time.

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Well, one other thing
we can use sequence for

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is maybe you want a vector
of some specific length.

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And you want it to start with some
number and end with some number.

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And all numbers in the middle
should be equally spaced apart.

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Well, seq() can do that as well
using an argument called length.out.

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A bit of a weird argument
name here, but length.out out

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can take as input some number
and create a sequence for us

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where the first number is
1, the last number is 10,

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and the total vector's length will
be this number here, in this case, 3,

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with all the numbers
evenly spaced apart.

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So let's try this out.

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I'll run line 1 here,
and I'll run line 3.

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And now we'll see,
true to its word, I get

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a vector of three numbers,
where each is evenly spaced out.

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And it begins with 1 and ends with 10.

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So this was a brief foray into vectors
how to create them manually with c(),

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how to repeat them using
rep(), how to, let's say,

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get a sequence of values using colon,
and how to modify or adjust that

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sequence using, in this
case, the seq() function.

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So this then was our short on vectors.

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And we'll see you next time.

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