Running R Code in RStudio

>> Hi. I'm Erica.

In this video, I'm going to show you
the two different places that you can run

your R code and the pros and cons
between them and how you can do that.

So, this might be a little bit

of a review and a reiteration of something
I've talked of, stuff

I've talked about in a previous video, but
I wanted to do a separate video on this

just to kind of, hit this topic,

kind of really hard,

so that way it makes sense.

So there are two different places
that you can, type your R code

and, use that to run.

So down here we have the,
in the bottom left

corner usually is the console window.

And you can type out code here

just fine.

And then go ahead
and press the enter button,

and it will run the code.

The major downside to doing,

anything down here in the console
is that as soon as you exit

out of RStudio,
this entire window is cleared and is gone.

So any code that you may have written
down here that you wanted to have saved,

it would have been gone.

So here comes the good reason
for the script window.

Up here you can type

the exact same code that you want up here.

Now notice if I'm to
press the enter button to run it,

nothing happens.

It works just like a regular enter does.

Like in a regular word or text document.

In order to get this code to run,
put your cursor on the line of code

that you want to run and either,
and you press the run button right here.

Notice it pushes that code

down here to the console
and runs it for you.

Let me try something different
so you can see how that works.

So five minus two. Okay.

And my cursor is on the line
I want to run. Run.

It pushes it down here.

Five minus two is three. Sweet.

Or a keyboard shortcut
that a lot of people use is-

Let's do another command. Just for fun.

Three times four is control enter

if you have a windows computer or
command enter if you have a mac computer.

So I'm going to press control enter.

And notice that pushes the code down here
to the console.

And it is run.

Notice that this also only shows

the input where this
shows the input and the output.

But if you had

some fancy code here
that you wanted to save for later,

you can do that by saving this document.

And it will save it as a

let's do, call this tutorial document,

or like tutorial doc.

And now it'll save it as a .R file
which means it's a script file.

So if you happen to exit out of R,

all this code that you have written
can now

be saved.

One other thing to know

about running our code,

is that notice this is the little,
this little, like, greater than sign

is the R prompt, meaning,
that is where code is entered, to be run.

If that little prompt is there,
that means that R is ready for a command

or a, piece of code to be given to it
so that it can run.

So notice if I was to do three

cool, it just spits out the number three.

But if I was to do,

something like this

where I had forgotten a parentheses.

It's going to have this little plus sign.

What that means is that R is usually
waiting for something else to happen.

And it can't finish executing the code

that you've given it,
until something else happens.

Usually
it's something that you have to do.

So in this case, it means you forgot
a parentheses somewhere.

That might seem
like a really simple mistake,

but as you start coding along
and you get things nested

inside of each other,
it gets to be really easy to forget

to make sure
all your parentheses are there.

Just so that you know,
the difference between,

what this is.
This is not a plus sign, like,

like,

I mean, it is a plus sign,
but it doesn't mean the same thing

as it does
in, like, arithmetic in, in mathematics.

Here on this side, when it's on the very
left hand side of the console window,

the little plus sign means that R
is waiting for something else to happen.

Now what if you want to make notes
for yourself in R,

but you want it to be in personal note

and it's not like actual R code
that you want to run.

Like you want to remind yourself,
okay, this is homework

problem one. Okay.

If you try and run that

R is not going to like it
because it doesn't

know what you're talking about here.

So if you want to create
a personal note to yourself that is, that

you don't want to have
the run as R code, you can,

make it a comment.

And how you can do that in R
is by using the pound symbol

or the hashtag symbol in front of it.

And anything after that symbol

to the end of the line
will be commented out.

So, I mean, I could have this
plus a bunch of space and then keep going

and notice how it's still kind of blue.

All of this is just a comment.

Now, if I go to the next line
and I start typing this

next line, now is going to be interpreted
as our code.

So if I were just to run this line
and then the next line,

it said, okay, this is a comment,
I'm not going to worry about it.

Then it gets to this line
and it's like, what the heck is this?

So if you want to create a personal note
for yourself,

you can do
do that with the hashtag or pound symbol.

And that works
for the entire rest of the line.

Okay.

So that is the pros
and cons of running your R code,

either in the script window
or in the console window.

And how you can also create comments

and how the console window is structured,
with the prompt

and with the greater than sign
and the plus sign and what those mean.

All right.

Have a good day
and we'll see you next time in R.