lintr

lintr

Static code analysis for R.

Basic Usage

library(lintr)

# Lint a file
lint("script.R")

# Lint a directory
lint_dir("R/")

# Lint a package
lint_package()

# Lint code string
lint("x=1")

Configuration

# .lintr file in project root
linters: linters_with_defaults(
    line_length_linter(120),
    commented_code_linter = NULL
  )
exclusions: list(
    "R/generated.R",
    "tests/testthat/helper.R" = list(1:10)
  )

Common Linters

# Style linters
assignment_linter()        # Use <- not =
spaces_inside_linter()     # No spaces inside brackets
commas_linter()            # Space after commas
infix_spaces_linter()      # Spaces around operators
line_length_linter(80)     # Line length limit
trailing_whitespace_linter()
trailing_blank_lines_linter()

# Best practice linters
no_tab_linter()
T_and_F_symbol_linter()    # Use TRUE/FALSE not T/F
equals_na_linter()         # Use is.na() not == NA
seq_linter()               # Use seq_len/seq_along
undesirable_function_linter()
undesirable_operator_linter()

Custom Configuration

# Use specific linters
lint("script.R", linters = list(
  assignment_linter(),
  line_length_linter(100),
  trailing_whitespace_linter()
))

# Modify defaults
lint("script.R", linters = linters_with_defaults(
  line_length_linter = line_length_linter(120),
  commented_code_linter = NULL  # Disable
))

Exclusions

# Exclude entire file in .lintr
exclusions: list("R/legacy.R")

# Exclude specific lines
exclusions: list(
    "R/file.R" = list(1, 5:10, 25)
  )

# Inline exclusion (in code)
x = 1 # nolint
x = 1 # nolint: assignment_linter

# Block exclusion
# nolint start
x = 1
y = 2
# nolint end

# Exclude next line
# nolint next
x = 1

IDE Integration

# RStudio
# Tools > Global Options > Code > Diagnostics
# Enable "Show diagnostics for R"

# VS Code
# Install R extension
# Lintr runs automatically

# Emacs/ESS
# (setq ess-use-flymake-for-R t)

CI/CD Integration

# GitHub Actions
# .github/workflows/lint.yaml
# - uses: r-lib/actions/setup-r@v2
# - run: |
#     install.packages("lintr")
#     lintr::lint_package()

# Check in CI
if (length(lintr::lint_package()) > 0) {
  stop("Linting errors found")
}