Basics of R, RStudio, and R Markdown

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# Basics of R, RStudio, & R Markdown

UO R Bootcamp 2025

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# RStudio IDE

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# RStudio IDE

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# RStudio IDE

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# RStudio IDE

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# RStudio IDE
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# RStudio IDE

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# Basic computing

``` r
# addition
2 + 3
```

```
## [1] 5
```

``` r
# subtraction
2 - 3
```

```
## [1] -1
```

``` r
# multiplication
2 * 3
```

```
## [1] 6
```

``` r
# division
10 / 2
```

```
## [1] 5
```

---
# Basic computing

``` r
# exponents
4^2
```

```
## [1] 16
```

``` r
# modulo
20 %% 10
```

```
## [1] 0
```

``` r
# roots
4^(1/2) #or sqrt(4)
```

```
## [1] 2
```

``` r
# absolute value
abs(-3)
```

```
## [1] 3
```

---
# Basic computing

R follows the order of operations (PEMDAS).

``` r
2 + 2 * 3
```

```
## [1] 8
```

``` r
(2 + 2) * 3
```

```
## [1] 12
```

***

All of the values computed thus far haven't been stored anywhere though...

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# Storing values in objects

To store a value, we need to assign it to an **object**.

To assign a value to an object, use the **assignment operator**. It looks like a left-pointing arrow:

.center[
### `<-`
]

--
***

Let's use `<-` to assign the number 8 to an object called `x`.

``` r
x <- 8 
```

Now we can call `x` by name, and it will print the value.

``` r
x
```

```
## [1] 8
```

---
# Style

Technically, both `<-` and `=` work as assignment operators. But we'll strictly use `<-` from here on out.

Note: We highly recommend following the [tidyverse style guide](https://style.tidyverse.org/). We'll talk more about the tidyverse tomorrow.

???

You want to use a consistent style so that others (including your future self) can easily and quickly read your code.

--
***

Tip: You will type `<-` a LOT. The keyboard shortcut `Alt` & `-` or `Option` & `-` can be used to insert a `<-`.

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# Storing values in objects

Now, let's take a look at the variable `y`...

``` r
# print y
y 
```

```
## Error: object 'y' not found
```

--
***

Whoops! We didn't assign anything to `y`. Calling a variable that doesn't exist leads to an **error message**.

You'll see a LOT of error messages when using R. Don't worry when this happens. This is 100% normal, and it happens to everyone all the time.

---
# Storing values in objects

``` r
# assign 2 to y
y <- 2

# print y
y
```

```
## [1] 2
```

---
# Storing values in objects

Now, we can use these variables in calculations.

***

Remember, `x <- 8` and `y <- 2`?

We can multiply them:

``` r
x * y
```

```
## [1] 16
```

---
# Storing values in objects

But, remember, if we want to save the output of that calculation, we need to assign it to an object!

``` r
# assign the the product of x and y to z
z <- x * y

# print z
z
```

```
## [1] 16
```

---
# Naming variables

You may be wondering how to name variables in R. There are just a few rules...

1. Object names should start with a letter.

2. Object names can contain alphanumeric characters, underscores (`_`), and/or periods (`.`).

3. R is case sensitive, so `A` and `a` are different variables.

---
# Naming variables

.footnote[Artwork by [@allison_horst](https://twitter.com/allison_horst)]

.pull-left[

### Some examples

+ this_is_snake_case
+ thisIsCamelCase
+ maybe.you.like.periods

I'll be using snake_case from here on out, but you can change to another option if you'd like.
]

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<img src="images/coding_cases.png" width="5335" />
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class: yourturn
# Your turn 1

Open the `01_r_basics.Rmd` file.

1. Create a variable called `var_1` that is equal to 4.

1. Then create a variable called `var_2` that is `var_1` raised to the power of 6. Print the results.

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class: solution
# Solution

.panelset[
.panel[.panel-name[Q1]

``` r
var_1 <- 4
```
]

.panel[.panel-name[Q2]

``` r
var_2 <- var_1^6
var_2
```

```
## [1] 4096
```
]
]

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# R Markdown

.footnote[Artwork by [@allison_horst](https://twitter.com/allison_horst)]

R Markdown allows you to combine R code and plain text together in the same document.

R Markdown documents end with the extension `.Rmd`. Let's take a look at how they work...

.center[
<img src="images/rmarkdown_wizards.png" width="70%" />
]

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# R Markdown

.footnote[Image from [Kieran Healy](https://socviz.co/gettingstarted.html)]

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class: yourturn
# Your turn 2

1. Go back to `01_r_basics.Rmd` and click `knit`. Take a look at the resulting file called `01_r_basics.html`.

2. Insert `author: [YOUR NAME]` after `title: "Basics of R, RStudio, & R Markdown"` but before `output: html_document`. Re-knit the document.

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# Solution

.panelset[
.panel[.panel-name[Q1]
<img src="images/rmarkdown_example.png" width="80%" />
]

.panel[.panel-name[Q2]

<img src="images/rmarkdown_example_author.png" width="80%" />
]
]

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# Q & A

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# Break!