class: center, middle, inverse, title-slide .title[ # <code>R</code> Basics ] .author[ ### Justin Post ] --- layout: true <div class="my-footer"><img src="data:image/png;base64,#img/logo.png" style="height: 60px;"/></div> --- # Our Tasks as a Data Scientist - Read raw data in or connect to a database - Manipulate data as need - Subset - Create new variables - Summarize data to create meaningful insights - Modeling data to make inference or predict outcomes - Communicate our results via dashboards, documents, model files, etc. `R` is a great language for all of these! --- # `R` vs `RStudio` - `R` is our programming language - Code in `R` through `RStudio` <div style = "float: left; width: 45%"> <img src="data:image/png;base64,#img/R.png" width="20%" /> </div> <div style = "float: left; width: 45%"> <img src="data:image/png;base64,#img/RStudio.png" width="20%" /> </div> --- # `RStudio` IDE In `RStudio`, four main locations - Console (& Terminal) - Scripting and Viewing Window - Files/Plots/Packages/Help - Environment (& Connections/Git) <img src="data:image/png;base64,#img/RStudioSnip.png" width="450px" /> --- # Console - Type code directly into the **console** for evaluation <div style = "float:left; width = 45%;"> ```r #simple math operations # <-- is a comment - code not evaluated 3 + 7 ``` ``` ## [1] 10 ``` ```r 10 * exp(3) #exp is exponential function ``` ``` ## [1] 200.8554 ``` ```r log(pi^2) #log is natural log by default ``` ``` ## [1] 2.28946 ``` </div> <div style = "float: left; width = 10%;"> </div> <div style = "float:left; width = 45%;"> ```r mean(cars$speed) ``` ``` ## [1] 15.4 ``` ```r hist(cars$speed) ``` <img src="data:image/png;base64,#04-R_Basics_files/figure-html/basic-1.png" width="250px" style="display: block; margin: auto;" /> </div> <!--Needed so the above renders correctly. Why, who knows? --> --- # Scripting and Viewing Window - Usually want to keep code for later use! - Write code in a 'script' and save script (or use markdown/quarto!) --- # Scripting and Viewing Window - Usually want to keep code for later use! - Write code in a 'script' and save script (or use markdown!) - From script can send code to console via: <ul> <li>"Run" button (runs current line)</li> <li>CTRL+Enter (PC) or Command+Enter (MAC)</li> <li>Highlight section and do above</li> </ul> --- # Files/Plots/Packages/Help - Files (navigate through files) - Created plots stored in `Plots` tab - Cycle through past plots\ - Easily save - Packages (update and install) - Documentation within RStudio via `help(...)` - Ex: `help(seq)` --- # Environment - We store **data/info/function/etc.** in `R` objects - Create an `R` object via `<-` (recommended) or `=` ```r #save for later avg <- (5 + 7 + 6) / 3 #call avg object avg ``` ``` ## [1] 6 ``` ```r #strings (text) can be saved as well words <- c("Hello there!", "How are you?") words ``` ``` ## [1] "Hello there!" "How are you?" ``` --- # Environment - Built-in objects exist like `letters` and `cars` don't show automatically ```r letters ``` ``` ## [1] "a" "b" "c" "d" "e" "f" "g" "h" "i" "j" "k" "l" "m" "n" "o" "p" "q" "r" "s" ## [20] "t" "u" "v" "w" "x" "y" "z" ``` ```r head(cars, n = 3) ``` ``` ## speed dist ## 1 4 2 ## 2 4 10 ## 3 7 4 ``` - `data()` shows available built-in data sets --- # `RStudio` IDE In `RStudio`, four main locations - Console (& Terminal) - Scripting and Viewing Window - Files/Plots/Packages/Help - Environment (& Connections/Git) <img src="data:image/png;base64,#img/RStudioSnip.png" width="450px" /> --- # `R` Objects and Classes How do we program in `R`? Using **objects** and **functions** - `R` has strong **O**bject **O**riented **P**rogramming (OOP) tools --- # `R` Objects and Classes How do we program in `R`? Using **objects** and **functions** - `R` has strong **O**bject **O**riented **P**rogramming (OOP) tools - Object: data structure with attributes (often a 'class') - Method: procedures (often 'functions') act on object based on attributes --- # `R` Objects and Classes Object: data structure with attributes (often a 'class') Method: procedures (often 'functions') act on object based on attributes - `R` functions like `plot()` act differently depending on object class ```r class(cars) ``` ``` ## [1] "data.frame" ``` ```r class(exp) ``` ``` ## [1] "function" ``` --- # `R` Objects and Classes Object: data structure with attributes (often a 'class') Method: procedures (often 'functions') act on object based on attributes - `R` functions like `plot()` act differently depending on object class ```r plot(cars) plot(exp) ``` <div style = "float: left; width = 45%;"> <img src="data:image/png;base64,#04-R_Basics_files/figure-html/plot1-1.png" width="220px" style="display: block; margin: auto;" /> </div> <div style = "float: left; width = 10%;"> </div> <div style = "float: left; width = 45%;"> <img src="data:image/png;base64,#04-R_Basics_files/figure-html/plot2-1.png" width="220px" style="display: block; margin: auto;" /> </div> --- # `R` Objects and Classes - Create an `R` object via `<-` (recommended) or `=` - allocates memory to object ```r vec <- c(1, 4, 10) vec ``` ``` ## [1] 1 4 10 ``` --- # `R` Objects and Classes - Create an `R` object via `<-` (recommended) or `=` - allocates memory to object ```r fit <- lm(dist ~ speed, data = cars) fit ``` ``` ## ## Call: ## lm(formula = dist ~ speed, data = cars) ## ## Coefficients: ## (Intercept) speed ## -17.579 3.932 ``` --- # `R` Objects and Classes - Function that creates the object determines the object's class ```r class(vec) ``` ``` ## [1] "numeric" ``` ```r summary(vec) ``` ``` ## Min. 1st Qu. Median Mean 3rd Qu. Max. ## 1.0 2.5 4.0 5.0 7.0 10.0 ``` --- # `R` Objects and Classes - Function that creates the object determines the object's class ```r class(fit) ``` ``` ## [1] "lm" ``` ```r summary(fit) ``` ``` ## ## Call: ## lm(formula = dist ~ speed, data = cars) ## ## Residuals: ## Min 1Q Median 3Q Max ## -29.069 -9.525 -2.272 9.215 43.201 ## ## Coefficients: ## Estimate Std. Error t value Pr(>|t|) ## (Intercept) -17.5791 6.7584 -2.601 0.0123 * ## speed 3.9324 0.4155 9.464 1.49e-12 *** ## --- ## Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1 ## ## Residual standard error: 15.38 on 48 degrees of freedom ## Multiple R-squared: 0.6511, Adjusted R-squared: 0.6438 ## F-statistic: 89.57 on 1 and 48 DF, p-value: 1.49e-12 ``` --- # Investigating Objects Many functions to help understand an `R` Object - `class()` - describes the `class` attribute of an `R` object ```r class(cars) ``` ``` ## [1] "data.frame" ``` ```r class(vec) ``` ``` ## [1] "numeric" ``` --- # Investigating Objects Many functions to help understand an `R` Object - `typeof()` - determines the (`R` internal) type or storage mode of any object ```r typeof(cars) ``` ``` ## [1] "list" ``` ```r typeof(vec) ``` ``` ## [1] "double" ``` --- # Investigating Objects Many functions to help understand an `R` Object - `str()` - compactly displays the internal structure of an `R` object ```r str(cars) ``` ``` ## 'data.frame': 50 obs. of 2 variables: ## $ speed: num 4 4 7 7 8 9 10 10 10 11 ... ## $ dist : num 2 10 4 22 16 10 18 26 34 17 ... ``` ```r str(vec) ``` ``` ## num [1:3] 1 4 10 ``` --- # To `R`! Quick example - Customize the appearance of `RStudio` - Check out the `help()` functionality - Create object(s) and inspect them --- # Recap! - `RStudio` provides a nice environment for coding - `R` has functions that can be used to create objects - Create an `R` Object with `<-` - Objects have attributes that determine how functions act! - `class()`, `typeof()`, and `str()` help understand your objects