Installation & Setup

Get R and RStudio installed on your system, explore the IDE, install your first packages, and run your first R script.

Step 1: Installing R from CRAN

R is distributed through the Comprehensive R Archive Network (CRAN). Visit cran.r-project.org and download the installer for your operating system.

# Windows:
https://cran.r-project.org/bin/windows/base/

# macOS:
https://cran.r-project.org/bin/macosx/

# Linux (Ubuntu/Debian):
sudo apt update
sudo apt install r-base

# Linux (Fedora):
sudo dnf install R

Step 2: Installing RStudio

RStudio is the most popular IDE for R. It is developed by Posit (formerly RStudio, PBC) and provides a powerful interface for writing, running, and debugging R code.

Download RStudio Desktop (free) from posit.co/download/rstudio-desktop.

The RStudio Interface

RStudio has four main panes:

1. Source Editor (top-left)

   Where you write R scripts (.R files) and R Markdown documents (.Rmd). Supports syntax highlighting, auto-completion, and code folding.

2. Console (bottom-left)

   The interactive R console where you can type and execute commands directly. Output appears here.

3. Environment / History (top-right)

   Shows all variables, data frames, and objects in your current R session. The History tab stores previously executed commands.

4. Files / Plots / Packages / Help (bottom-right)

   Browse files, view generated plots, manage installed packages, and access documentation.

Installing Packages

R's power comes from its package ecosystem. Packages add new functions and capabilities.

# Install a package from CRAN
install.packages("tidyverse")

# Install multiple packages at once
install.packages(c("dplyr", "ggplot2", "readr"))

# Load a package into your session
library(tidyverse)

# Check if a package is installed
require(ggplot2)  # Returns TRUE/FALSE

# See all installed packages
installed.packages()

CRAN vs GitHub Packages

R Markdown Basics

R Markdown lets you combine R code with narrative text to create reproducible documents, reports, and presentations.

---
title: "My First Report"
author: "Your Name"
output: html_document
---

## Analysis

```{r}
summary(mtcars)
```

The mtcars dataset has `r nrow(mtcars)` observations.

Running Scripts

There are several ways to run R code in RStudio:

• Run current line: Place cursor on a line and press Ctrl+Enter (Windows/Linux) or Cmd+Enter (macOS).
• Run selected code: Highlight code and press Ctrl+Enter.
• Run entire script: Press Ctrl+Shift+Enter or click the "Source" button.
• From terminal: Run Rscript my_script.R from the command line.

# Run an R script from the command line
Rscript my_script.R

# Run with arguments
Rscript my_script.R arg1 arg2

# Start interactive R session
R