r-flextable

R flextable

Overview

flextable creates publication-quality tables that render consistently across Word, PowerPoint, HTML, and PDF.

Core principle: Separate data from display. Build from a data.frame, then layer formatting declaratively using selectors.

References

Read references/API.md before writing code.

• references/API.md - Complete function reference
• references/overview.md - Core concepts and workflow
• references/formatting.md - Styling and appearance
• references/layout.md - Structure and merging
• references/selectors.md - Targeting cells for formatting
• references/output.md - Rendering to different formats

When to Use

Use flextable when:

• Output to Word/PowerPoint required
• Need cell merging, conditional formatting, mini charts
• Cross-references and auto-numbered captions
• Same table across multiple formats

Consider alternatives:

• HTML-only: gt or reactable
• LaTeX-heavy: kableExtra
• Interactive dashboards: DT

Quick Reference

Task	Function
Create table	flextable(df)
Format numbers	colformat_double(), colformat_int()
Bold/italic/color	bold(), italic(), color()
Background color	bg()
Merge cells	merge_v(), merge_h(), merge_at()
Add header	add_header_row()
Auto-size	autofit()
Apply theme	theme_vanilla(), theme_zebra()
Save to Word	save_as_docx()
Save to PowerPoint	save_as_pptx()

Core Pattern

library(flextable)

# Create -> format -> output
ft <- flextable(head(mtcars, 5)) |>
  colformat_double(digits = 1) |>
  # Conditional formatting with formula selectors
  color(i = ~ mpg > 20, j = "mpg", color = "darkgreen") |>
  bold(i = ~ mpg > 20, j = "mpg") |>
  # Spanning header
  add_header_row(
    values = c("Performance", "Engine", "Transmission"),
    colwidths = c(2, 4, 5)
  ) |>
  theme_vanilla() |>
  autofit()

save_as_docx(ft, path = "table.docx")

Selectors (Key Concept)

Target cells for formatting:

# Row selector (formula)
bold(ft, i = ~ cyl == 6)

# Column selector
bg(ft, j = ~ mpg + hp, bg = "lightgray")

# Part selector
bold(ft, part = "header")

See references/selectors.md for details on multi-content cells, mini charts, output-specific notes.

Common Mistakes

Mistake	Fix
Theme doesn't format new header	Apply theme AFTER add_header_row()
autofit() overflows margins	Use set_table_properties(layout = "autofit")
height() has no effect	Set hrule(rule = "exact") first
Formula selectors fail in header	Use integer indices for header rows
Images missing in Word	Use officedown::rdocx_document()
PDF ignores padding	Use ft.tabcolsep chunk option
add_header_row values wrong	One value per span; colwidths sum to ncol

Advanced

See references/ for:

• API.md: Complete function reference (240+ functions)
• selectors.md: Multi-content cells, mini charts, output-specific notes
• formatting.md: All formatting functions and options
• layout.md: Merging, sizing, headers/footers
• output.md: Rendering to all formats