12  RStudio Projects & Data Import

Learning Objectives: After this chapter you will be able to: - Work inside an RStudio Project (.Rproj) instead of setwd(). - Build portable paths with here::here(). - Read CSV files with readr::read_csv() and Excel files with readxl::read_excel().

library(readr)
library(readxl)
library(here)

12.1 Why avoid setwd()

setwd("C:/Users/you/project") hard-codes a path that exists only on your machine. Anyone else who opens the script — or you on a different computer — gets an error. An RStudio Project (.Rproj) fixes this: opening the .Rproj file sets the working directory to the project folder automatically, so relative paths just work.

Workflow: File → New Project → New Directory (or Existing Directory) → give it a name. From then on, open the .Rproj file, not individual scripts.

12.2 Portable paths with here

The here package builds paths from the project root, wherever the project lives on disk:

here("data", "students.csv")

[1] "F:/R/ebooks/intro-r/data/students.csv"

Common Mistake: Paths with ../ or C:/... break when the project moves. If a path starts with a drive letter or ../, rewrite it with here().

12.3 Reading CSV files

Practice data lives in the data/ directory (CC0 / public domain, created for this book). Read it with read_csv():

students <- read_csv(here("data", "students.csv"))
students

# A tibble: 5 × 3
  name    age score
  <chr> <dbl> <dbl>
1 Asha     21    88
2 Ravi     22    92
3 Meera    20    79
4 Arjun    23    95
5 Divya    21    84

12.4 Reading Excel files

read_excel() works the same way for .xlsx files — sheet 1 by default:

students_xl <- read_excel(here("data", "students.xlsx"))
students_xl

# A tibble: 5 × 3
  name    age score
  <chr> <dbl> <dbl>
1 Asha     21    88
2 Ravi     22    92
3 Meera    20    79
4 Arjun    23    95
5 Divya    21    84

Try it in your browser

Edit the code below and press Run. It executes entirely in your browser via WebR — no R installation needed. The runtime downloads once, on this page only.

12.5 Practice Check

Knowledge Check: Project-relative paths Why does read_csv(here("data", "students.csv")) keep working when you move the whole project folder to another computer, but read_csv("C:/Users/you/project/data/students.csv") does not?

Click to reveal answer

Answer: here() resolves the path relative to the project root at run time, so it adapts to the new location. The C:/... path is absolute and points to a folder that does not exist on the other computer.

Explanation: Projects + here() keep every path portable (project root → data → file); absolute paths and setwd() tie the script to one machine.

Knowledge Check: Why .Rproj beats setwd() What breaks when you share a script containing setwd("C:/Users/you/project") with a colleague?

Click to reveal answer

Answer: The script errors because that folder does not exist on your colleague’s machine.

Explanation: setwd() with an absolute path ties the script to one computer; opening a shared .Rproj file sets everyone’s working directory to the project folder automatically.

Knowledge Check: here() resolution Your project lives at D:/work/survey and contains data/resp.csv. What does here("data", "resp.csv") return?

Click to reveal answer

Answer: D:/work/survey/data/resp.csv (i.e. project root → data → resp.csv).

Explanation: here() anchors paths at the project root (where the .Rproj file lives), joining each additional component with the correct separator for your OS.

Knowledge Check: read_csv() vs read.csv() Name one practical advantage of readr::read_csv() over base R’s read.csv() for a beginner.

Click to reveal answer

Answer: Any one of: it never converts strings to factors, it prints a compact tibble preview, or it reports column types as it reads.

Explanation: read_csv() uses modern defaults (no stringsAsFactors surprises) and tells you the parsed type of each column, so mismatches are visible immediately.

Knowledge Check: Excel sheets read_excel(here("data", "students.xlsx")) reads which sheet by default, and how would you read the second sheet instead?

Click to reveal answer

Answer: The first sheet by default; pass sheet = 2 (or the sheet name) to read the second sheet.

Explanation: read_excel() defaults to sheet 1; the sheet argument selects another sheet by position or name.