Create a Conditional Style Override

Creates a data-driven style that is evaluated against cell values at application time (inside fr_styles()). Rows matching the condition receive the specified style properties. This avoids hard-coding row indices when styling based on content.

Usage

fr_style_if(
  condition,
  cols = NULL,
  apply_to = "cell",
  bold = NULL,
  italic = NULL,
  underline = NULL,
  fg = NULL,
  bg = NULL,
  font_size = NULL,
  align = NULL
)

Arguments

condition

A one-sided formula or function that returns a logical vector. The formula uses .x as the pronoun for the column values (converted via rlang::as_function()):

• ~ .x == "Total" — match exact text

• ~ as.numeric(.x) < 0.05 — numeric comparison

• ~ grepl("^N=", .x) — pattern matching

When cols = NULL, .x receives seq_len(nrow(data)) (row indices), useful for zebra striping: ~ (.x %% 2) == 0.

cols

Column selection for the condition. Accepts any of:

• A character vector of column names: cols = c("zom_50mg", "placebo")

• A tidyselect expression: cols = starts_with("zom_")

• NULL (default) — row-index-based conditions (e.g., zebra striping).

The condition is applied to the values of each selected column independently. Tidyselect expressions are resolved when the style is applied via fr_styles().

apply_to

Character scalar. Controls scope of matched rows:

• "cell" (default): style only the cells where the condition is TRUE.

• "row": style all columns in rows where the condition is TRUE.

bold, italic, underline

Logical or NULL to leave unchanged.

fg

Foreground (text) colour: hex string or CSS named colour, or NULL.

bg

Background (fill) colour: hex string or CSS named colour, or NULL.

font_size

Font size in points, or NULL.

align

Horizontal alignment ("left", "center", "right", "decimal"), or NULL.

Value

An fr_conditional_style object for use in fr_styles().

See also

fr_styles(), fr_style(), fr_rows_matches()

Examples

## ── Bold "Total" rows ─────────────────────────────────────────────────────

tbl_demog |>
  fr_table() |>
  fr_styles(
    fr_style_if(
      cols = "characteristic",
      condition = ~ .x == "Total",
      apply_to = "row",
      bold = TRUE
    )
  )
#> 
#> ── fr_spec: Table 
#> Data: 28 rows x 6 columns
#> Page: landscape letter, 9pt Courier New
#> Header: valign=bottom

## ── Zebra striping ────────────────────────────────────────────────────────

tbl_demog |>
  fr_table() |>
  fr_styles(
    fr_style_if(
      condition = ~ (.x %% 2) == 0,
      bg = "#F5F5F5",
      apply_to = "row"
    )
  )
#> 
#> ── fr_spec: Table 
#> Data: 28 rows x 6 columns
#> Page: landscape letter, 9pt Courier New
#> Header: valign=bottom
#> Styles: 1 override

## ── Numeric condition: highlight small p-values ──────────────────────────

# Create a table with a p-value column
pval_data <- data.frame(
  characteristic = c("Age", "Sex", "Weight"),
  treatment = c("50 (23.5)", "30 (14.1)", "45 (21.1)"),
  placebo   = c("55 (25.8)", "28 (13.1)", "52 (24.4)"),
  pvalue    = c("0.042", "0.310", "0.003"),
  stringsAsFactors = FALSE
)

pval_data |>
  fr_table() |>
  fr_styles(
    fr_style_if(
      cols = "pvalue",
      condition = ~ as.numeric(.x) < 0.05,
      apply_to = "row",
      bold = TRUE, fg = "#CC0000"
    )
  )
#> 
#> ── fr_spec: Table 
#> Data: 3 rows x 4 columns
#> Page: landscape letter, 9pt Courier New
#> Header: valign=bottom
#> Styles: 1 override

## ── Pattern matching with grepl ────────────────────────────────────────────

tbl_ae_soc |>
  fr_table() |>
  fr_styles(
    fr_style_if(
      cols = "soc",
      condition = ~ grepl("SKIN|GASTROINTESTINAL", .x, ignore.case = TRUE),
      apply_to = "row",
      bg = "#FFF3CD"
    )
  )
#> 
#> ── fr_spec: Table 
#> Data: 96 rows x 7 columns
#> Page: landscape letter, 9pt Courier New
#> Header: valign=bottom
#> Styles: 1 override

## ── apply_to = "cell": colour only the matching cell ───────────────────────

tbl_disp |>
  fr_table() |>
  fr_styles(
    fr_style_if(
      cols = c("placebo", "zom_50mg", "zom_100mg"),
      condition = ~ grepl("0", .x),
      apply_to = "cell",
      fg = "#999999", italic = TRUE
    )
  )
#> 
#> ── fr_spec: Table 
#> Data: 8 rows x 5 columns
#> Page: landscape letter, 9pt Courier New
#> Header: valign=bottom
#> Styles: 3 overrides

## ── Function form (not formula) for the condition ──────────────────────────

is_total <- function(x) x == "Total"

tbl_demog |>
  fr_table() |>
  fr_styles(
    fr_style_if(
      cols = "characteristic",
      condition = is_total,
      apply_to = "row",
      bold = TRUE, bg = "#E8E8E8"
    )
  )
#> 
#> ── fr_spec: Table 
#> Data: 28 rows x 6 columns
#> Page: landscape letter, 9pt Courier New
#> Header: valign=bottom

## ── Multiple cols: evaluate condition on several columns ───────────────────

tbl_demog |>
  fr_table() |>
  fr_styles(
    fr_style_if(
      cols = c("placebo", "zom_50mg", "zom_100mg", "total"),
      condition = ~ grepl("^0", .x),
      apply_to = "cell",
      fg = "#999999"
    )
  )
#> 
#> ── fr_spec: Table 
#> Data: 28 rows x 6 columns
#> Page: landscape letter, 9pt Courier New
#> Header: valign=bottom
#> Styles: 2 overrides