tab_style_body: Target cells in the table body and style accordingly

Description

With the tab_style_body() function we can target cells though value, regex, and custom matching rules and apply styles to them and their surrounding context (i.e., styling an entire row or column wherein the match is found). Just as with the general tab_style() function, this function is focused on the application of styles for HTML output only (as such, other output formats will ignore all tab_style() calls).

With the collection of cell_*() helper functions available in gt, we can modify:

the background color of the cell (cell_fill(): color)
the cell's text color, font, and size (cell_text(): color, font, size)
the text style (cell_text(): style), enabling the use of italics or oblique text.
the text weight (cell_text(): weight), allowing the use of thin to bold text (the degree of choice is greater with variable fonts)
the alignment and indentation of text (cell_text(): align and indent)
the cell borders (cell_borders())

Usage

tab_style_body(
  data,
  style,
  columns = everything(),
  rows = everything(),
  values = NULL,
  pattern = NULL,
  fn = NULL,
  targets = "cell",
  extents = "body"
)

Value

An object of class gt_tbl.

Arguments

data: A table object that is created using the gt() function.
style: a vector of styles to use. The cell_text(), cell_fill(), and cell_borders() helper functions can be used here to more easily generate valid styles. If using more than one helper function to define styles, all calls must be enclosed in a list(). Custom CSS declarations can be used for HTML output by including a css()-based statement as a list item.
columns: Optional columns for constraining the targeting process. Providing everything() (the default) results in cells in all columns being targeting (this can be limited by rows however). Can either be a series of column names provided in c(), a vector of column indices, or a helper function focused on selections. The select helper functions are: starts_with(), ends_with(), contains(), matches(), one_of(), num_range(), and everything().
rows: Optional rows for constraining the targeting process. Providing everything() (the default) results in all rows in columns being targeted. Alternatively, we can supply a vector of row captions within c(), a vector of row indices, or a helper function focused on selections. The select helper functions are: starts_with(), ends_with(), contains(), matches(), one_of(), num_range(), and everything(). We can also use expressions to filter down to the rows we need (e.g., [colname_1] > 100 & [colname_2] < 50).
values: The specific value or values that should be targeted for styling. If pattern is also supplied then values will be ignored.
pattern: A regex pattern that can target solely those values in character-based columns. If values is also supplied, pattern will take precedence.
fn: A supplied function that operates on each cell of each column specified through columns and rows. The function should be fashioned such that a single logical value is returned. If either of values or pattern is also supplied, fn will take precedence.
targets: A vector of styling target keywords to contain or expand the target of each cell. By default, this is a vector just containing "cell". However, the keywords "row" and "column" may be used separately or in combination to style the target cells' associated rows or columns.
extents: A vector of locations to project styling. By default, this is a vector just containing "body", whereby styled rows or columns (facilitated via inclusion of the "row" and "column" keywords in targets) will not permeate into the stub. The additional keyword "stub" may be used alone or in conjunction with "body" to project or expand the styling into the stub.

Examples

Use exibble to create a gt table with a stub and row groups. This contains an assortment of values that could potentially undergo some styling via tab_style_body().

gt_tbl <-
  exibble %>%
  gt(
    rowname_col = "row",
    groupname_col = "group"
  )

Cells in the table body can be styled through specification of literal values in the values argument of tab_style_body(). It's okay to search for numerical, character, or logical values across all columns. Let's target the values 49.95 and 33.33 and style those cells with an orange fill.

gt_tbl %>%
  tab_style_body(
    style = cell_fill(color = "orange"),
    values = c(49.95, 33.33)
  )

This image of a table was generated from the first code example in the `tab_style_body()` help file.

Multiple styles can be combined in a list, here's an example of that using the same cell targets:

gt_tbl %>%
  tab_style_body(
    style = list(
      cell_text(font = google_font("Inter"), color = "white"),
      cell_fill(color = "red"),
      cell_borders(
        sides = c("left", "right"),
        color = "steelblue",
        weight = px(4)
      )
    ),
    values = c(49.95, 33.33)
  )

This image of a table was generated from the second code example in the `tab_style_body()` help file.

You can opt to color entire rows or columns (or both, should you want to) with those specific keywords in the targets argument. For the 49.95 value we will style the entire row and with 33.33 the entire column will get the same styling.

gt_tbl %>%
  tab_style_body(
    style = cell_fill(color = "lightblue"),
    values = 49.95,
    targets = "row"
  ) %>%
  tab_style_body(
    style = cell_fill(color = "lightblue"),
    values = 33.33,
    targets = "column"
  )

This image of a table was generated from the third code example in the `tab_style_body()` help file.

In a minor variation to the prior example, it's possible to extend the styling to other locations, or, entirely project the styling elsewhere. This is done with the extents argument. Valid keywords that can be included in the vector are: "body" (the default) and "stub". Let's take the previous example and extend the styling of the row into the stub.

gt_tbl %>%
  tab_style_body(
    style = cell_fill(color = "lightblue"),
    values = 49.95,
    targets = "row",
    extents = c("body", "stub")
  ) %>%
  tab_style_body(
    style = cell_fill(color = "lightblue"),
    values = 33.33,
    targets = "column"
  )

This image of a table was generated from the fourth code example in the `tab_style_body()` help file.

We can also use the pattern argument to target cell values in character-based columns. The "fctr" column is skipped because it is in fact a factor-based column.

gt_tbl %>%
  tab_style_body(
    style = cell_fill(color = "green"),
    pattern = "ne|na"
  )

This image of a table was generated from the fifth code example in the `tab_style_body()` help file.

For the most flexibility in targeting, it's best to use the fn argument. The function you give to fn will be invoked separately on all cells so the columns argument of tab_style_body() might be useful to limit which cells should be evaluated. For this next example, the supplied function should only be used on numeric values and we can make sure of this by using columns = where(is.numeric).

gt_tbl %>%
  tab_style_body(
    columns = where(is.numeric),
    style = cell_fill(color = "pink"),
    fn = function(x) x >= 0 && x < 50
  )

This image of a table was generated from the sixth code example in the `tab_style_body()` help file.

Function ID