Skip to main content

Documentation Index

Fetch the complete documentation index at: https://mintlify.com/davidgohel/flextable/llms.txt

Use this file to discover all available pages before exploring further.

Every flextable is divided into three parts: header, body, and footer. Most formatting functions accept a part argument that controls which part they act on.

​
Creating a flextable

Pass any data.frame to flextable() to create a table: 
library(flextable)

ft <- flextable(head(mtcars))
ft
The function signature is: 
flextable(data, col_keys = names(data), cwidth = .75, cheight = .25, use_labels = TRUE)
  • data — a data.frame (tibbles and data.tables are coerced automatically).
  • col_keys — the columns to display, in display order. Defaults to all column names.
  • cwidth, cheight — initial cell width and height in inches.
  • use_labels — if TRUE, column labels from labelled data will be used in the header.

​
The three parts

1

Header

The header is created automatically from the column names (or col_keys). Each column name becomes a single header cell. If use_labels = TRUE and the dataset carries variable labels, those labels replace the raw column names.
# Default: header shows column names
ft <- flextable(head(iris))

# Override header labels after creation
ft <- set_header_labels(ft,
  Sepal.Length = "Sepal length",
  Sepal.Width  = "Sepal width"
)
The header always has exactly one row after construction. Additional header rows can be added with add_header_row().
2

Body

The body contains the data rows from the supplied data.frame. The number of body rows equals nrow(data).
ft <- flextable(head(airquality, 10))
# body has 10 rows
Formatting functions target the body by default (part = "body").
3

Footer

The footer is empty by default. Add content with add_footer_lines(), add_footer_row(), or footnote().
ft <- flextable(head(airquality)) |>
  add_footer_lines("Source: New York State Department of Conservation")

​
The col_keys parameter and blank columns

col_keys controls which columns appear and in what order. If a name in col_keys does not exist in the data, flextable adds it as a blank column — useful for inserting spacing columns or gaps between groups. 
# Reorder columns
ft <- flextable(head(mtcars), col_keys = c("cyl", "mpg", "hp"))

# Insert a blank spacer column between two groups
ft <- flextable(
  head(mtcars),
  col_keys = c("mpg", "cyl", "gap_1", "disp", "hp")
)
Columns named in col_keys that are not in the data are created as empty character columns. They appear blank in all output formats. You can use them as visual separators.
Duplicate values in col_keys are not allowed and will raise an error.

​
The part argument

Formatting functions like bold(), color(), bg(), and align() all accept a part argument:
ValueTargets
"body"Data rows (default)
"header"Header rows
"footer"Footer rows
"all"All three parts
ft <- flextable(head(mtcars)) |>
  bold(part = "header") |>          # bold header only
  bg(bg = "#f5f5f5", part = "all") |>  # grey background everywhere
  color(color = "red", part = "body")   # red text in body only
When part = "all", the operation is applied to each part independently. Formula row selectors (i = ~ condition) cannot be used with part = "all" or with "header" / "footer", because those parts store only character values — see Selectors for details.

​
Inspecting a flextable

Use these functions to query the dimensions of a flextable object: 
ft <- flextable(head(mtcars))

# Number of columns displayed
ncol_keys(ft)
#> [1] 11

# Number of rows in a specific part
nrow_part(ft, part = "body")
#> [1] 6

nrow_part(ft, part = "header")
#> [1] 1

nrow_part(ft, part = "footer")
#> [1] 0

# Overall dimensions: returns a list with widths and heights in inches
dim(ft)
nrow_part() is especially useful when you need to programmatically target the last row: 
ft <- flextable(iris[48:52, ])

# Bold the last body row
ft <- bold(ft, i = nrow_part(ft, part = "body"), part = "body")

​
Quick construction with qflextable()

qflextable() is a shortcut that creates a flextable, sets fixed table layout, and calls autofit() in one step: 
ft <- qflextable(head(cars))
It is equivalent to: 
ft <- flextable(head(cars))
ft <- set_table_properties(ft, layout = "fixed")
ft <- autofit(ft)
Use qflextable() when you want a quick, well-sized table without further customization.

​
Pipe-friendly API

All flextable functions accept a flextable object as their first argument and return a modified flextable object. This makes them composable with the native pipe (|>) or magrittr pipe (%>%): 
ft <- flextable(head(airquality)) |>
  theme_vanilla() |>
  bold(part = "header") |>
  color(color = "#2B5797", part = "header") |>
  add_footer_lines("Source: New York State Department of Conservation") |>
  autofit()
Each call in the chain modifies the table and passes it to the next function. The final object is printed or saved.

​
Internal object structure

A flextable is an R list of class "flextable". Its top-level elements are:
ElementDescription
$headerA complex_tabpart with header rows, styles, and content
$bodyA complex_tabpart with body rows, styles, and content
$footerA complex_tabpart with footer rows, styles, and content
$col_keysCharacter vector of displayed column names in order
$blanksNames of blank columns added from col_keys
$captionCaption settings set by set_caption()
Each part stores its own dataset, content (text chunks), column widths, row heights, span matrices, and style properties.

Build docs developers (and LLMs) love

Get started for freeTalk to us