[Auto-generated transcript. Edits may have been applied for clarity.]
In this video, I'll walk you through how to use the hair function to help you r find your files.

Okay, so let's first talk about what the problem actually is and how here helps to solve that.

So your code runs on your computer. But file paths that you specify um, are kind of specific to your folder folders and your folder structure.

So if we look at this bit of code we're trying to read in a data file in this line of code.

Right. We've got the readcsv function here.

And then we need to tell our where to look and what the file is called.

Now this bit is specific to my machine. This is my home directory.

And then I go through a series of folders, um, until I get to the to the one where this particular, um, file is.

Now, if you, um, specify what is called an absolute file path like this, then it will only work on this computer.

And and if I somehow move any part of it, the file path will break.

And then, um, when you try to run this code, you will get an error message saying file not found.

Okay. So what does here do here?

Finds the root folder of your project automatically. And then it builds file paths relative to that root.

So if um, you move that project to kind of a different location on your computer or to a different computer, the file path will still work.

Okay, so what do we need to do for this to work? Um, step one is to work in a project.

So you need to create a project in R so your project folder, when you've done that, we'll have, um, a file that has the our proj extension.

So that particular file marks the project route.

And here looks for clues like a project, um, an R proj files or a project file to identify the route.

So, um, when you then open that project by double clicking on that file, um,

then it will know, um, to look for to, to kind of start looking for files from there.

So it's important that when you start work in our studio, you open that project file.

Rather than opening scripts on their own. Then we need to load the package.

Write as we've been doing in the labs. Um, we need to tell our which packages to use.

So we would do this in, in this way. We'd say library and then here.

So the here package um, yeah. Needs to be loaded for it to work.

Now when you load the here package, it will print a message to the console showing the project where the project root is.

So, um, it is worth checking that that folder is what you expect it to be.

If you want to check where home is.

So where here starts, um, you can put this little bit of code here and just the opening closing bracket into the console.

run that and then it will give you the path to your project route.

So if it is the wrong folder, you're probably not working inside your project.

Okay, so the next step then is to build your relative file path.

So um, the kind of the main ingredients for that are as follows.

We use the function here followed by opening brackets.

And then we need to tell it okay. We'll start looking in in the project route.

But from there I want you to go to a particular folder.

So um, we give it the path to the folder and then we add a comma, and then we give it the the name of the file including the file extension.

So each folder of file name is separate is a separate part in here and it needs to be in double quotation marks.

That's called, um, a quoted argument. Um, and something that it is often used for is to read in a file.

That's why how we've been using it. Right.

Um, so if we go, uh, kind of back to our readcsv function, if we use here, this is what the file path would look like.

So, um, I would, it would, you would give it the function here, and then it would start looking in my project route.

And from there it needs to go to, to this folder. And then I in there I have a folder called files.

And in there I have a folder called week two. And that is where that file sits.

So in this particular example the here function sits inside the readcsv function.

So that's a very common use. Now there are a few things that often.

Um. A few common mistakes that I wanted to point out here.

So sometimes people try this, they kind of have the folder and then a slash and then a file name.

That might work on some systems, but using separate arguments separated by a comma is much safer.

That will work on any machine. Um, if you open a script on its own rather than from inside a project, then things also might not work.

So you don't want to do that. And another common mistake is kind of typos in the folder name or the file name.

And so it needs to be um the file path.

And the file name needs need to be exactly, uh, like they are on your machine,

including the use of capitals or spaces or any of those things and extensions.

So yeah, if you get file mode found for something, then these are three things to look for.

Have you accidentally added a slash instead of a comma? Um, are you working from inside a project?

If not, then just start over and open a project. And that or the project in which these folders should be sitting.

Um, and are there any typos?

Um, and as I mentioned before, if you need to check where our starts looking when you run here, then you can use this bit of code.

Just put that in the console and it will show you what the root is.

Okay. So to summarise work inside a project.

So we created the project kind of in week one.

Um if you want to revisit that uh, so you need to be looking for a file that has this extension.

So it might be something like a psych for one for one project.

Um, so when you start up RStudio. Uh, you've logged into the R server.

Then open that project, and from there, upload your files and start working.

Remember to load the here library and then, um, use this kind of general format to, to point towards your files.

So the function and then the folder structure might be more than one folder comma.

And then the file name including the extension.

Now as I said if you have to kind of move your that project around or if you need to share it with other people, the code will still work.

All right. Now let's do, uh, have a look at that in our studio.

So, um, here we are looking at the R server.

And you can see here that I am inside my psych 4141 project.

So if it says none here next to this cube, uh, you can open a project.

If you don't have a project, you can create a new one. But I'm currently inside that project, so that's the first thing to check.

Um, right. So I'm inside my project and I'm going to open a script.

I'm going to go to the source View because I'm going to be doing some writing, some code and let's say, uh, there is some code here to load libraries.

Um, so here is this is where we load the here package.

Might be a little bit confusing that both the package is called here.

And the function that we use is also called here.

So I run that. So now it tells me where he starts, right?

So it says home. This is me and this is my project folder.

So that is something that I need to remember if I want to look that up.

Um. I've forgotten. Right. Then I go to the console and type here.

Press enter and it will give me that that home directory kind.

So if I then want to read in a file, um, like in this code here, eh.

Um, so I've got my read underscore, csv, uh, opening brackets for that function.

And inside there I say okay I'm going to use here. So I type here opening brackets.

Um, and I it automatically starts looking in this folder.

Right. So that's over there. So you can kind of see home that's at the bottom as well.

Um and well that's my name, then R and then psych for one for one.

So I don't have to specify that in um in here because it already knows that.

But that is not where that file sits. That file sits in another folder.

And I can get to that folder by pointing it to week two.

And then for one, for one week two lab. So I need to add here week week two for one for one week two underscore lab.

Then we have the comma here. So this is the location. Then we have the comma.

And then we give the file name. And let's just check that that file name is correct.

So data underscore BMW three dot CSV.

So if I now run this it should all work. And indeed it does.

It has read in that file okay that's it for now.