tab_style_body: Target cells in the table body and style accordingly

In gt: Easily Create Presentation-Ready Display Tables

Target cells in the table body and style accordingly

Description

With tab_style_body() we can target cells through 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"
)

Arguments

data	The gt table data object ⁠obj:<gt_tbl>⁠ // required This is the gt table object that is commonly created through use of the gt() function.
style	Style declarations ⁠<style expressions>⁠ // required The styles to use for the targeted cells. cell_text(), cell_fill(), and cell_borders() 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	Columns to target ⁠<column-targeting expression>⁠ // default: everything() The columns to which the targeting operations are constrained. Can either be a series of column names provided in c(), a vector of column indices, or a select helper function (e.g. starts_with(), ends_with(), contains(), matches(), num_range(), and everything()). This argument works in tandem with the spanners argument.
rows	Rows to target ⁠<row-targeting expression>⁠ // default: everything() In conjunction with columns, we can specify which of their rows should form a constraint for targeting operations. The default everything() results in all rows in columns being formatted. Alternatively, we can supply a vector of row IDs within c(), a vector of row indices, or a select helper function (e.g. starts_with(), ends_with(), contains(), matches(), 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	Values for targeting ⁠vector<character|numeric|integer>⁠ // default: NULL (optional) The specific value or values that should be targeted for styling. If pattern is also supplied then values will be ignored.
pattern	Regex pattern for targeting ⁠scalar<character>⁠ // default: NULL (optional) A regex pattern that can target solely those values in character-based columns. If values is also supplied, pattern will take precedence.
fn	Function to return logical values ⁠<function>⁠ // default: NULL (optional) 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	Styling targets ⁠vector<character>⁠ // default: "cell" 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	Styling extents ⁠vector<character>⁠ // default: "body" 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.

Value

An object of class gt_tbl.

Targeting cells with columns and rows

Targeting of values is done through columns and additionally by rows (if nothing is provided for rows then entire columns are selected). The columns argument allows us to constrain a subset of cells contained in the resolved columns. We say resolved because aside from declaring column names in c() (with bare column names or names in quotes) we can use tidyselect-style expressions. This can be as basic as supplying a select helper like starts_with(), or, providing a more complex incantation like

where(~ is.numeric(.x) && max(.x, na.rm = TRUE) > 1E6)

which targets numeric columns that have a maximum value greater than 1,000,000 (excluding any NAs from consideration).

By default all columns and rows are selected (with the everything() defaults). Cell values that are incompatible with a given search will be skipped over. So it's safe to select all columns with a type of search (only those values that can be formatted will be formatted), but, you may not want that. One strategy is to format the bulk of cell values with one formatting function and then constrain the columns for later passes with other types of formatting (the last formatting done to a cell is what you get in the final output).

Once the columns are targeted, we may also target the rows within those columns. This can be done in a variety of ways. If a stub is present, then we potentially have row identifiers. Those can be used much like column names in the columns-targeting scenario. We can use simpler tidyselect-style expressions (the select helpers should work well here) and we can use quoted row identifiers in c(). It's also possible to use row indices (e.g., c(3, 5, 6)) though these index values must correspond to the row numbers of the input data (the indices won't necessarily match those of rearranged rows if row groups are present). One more type of expression is possible, an expression that takes column values (can involve any of the available columns in the table) and returns a logical vector.

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)
  )

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)
  )

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"
  )

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"
  )

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"
  )

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
  )

Styling every NA value in a table is also easily accomplished with the fn argument by way of is.na().

gt_tbl |>
  tab_style_body(
    style = cell_text(color = "red3"),
    fn = function(x) is.na(x)
  ) |>
  sub_missing(missing_text = "Not Available")

Function ID

2-11

Function Introduced

v0.8.0 (November 16, 2022)

See Also

Other part creation/modification functions: tab_caption(), tab_footnote(), tab_header(), tab_info(), tab_options(), tab_row_group(), tab_source_note(), tab_spanner(), tab_spanner_delim(), tab_stub_indent(), tab_stubhead(), tab_style()

gt documentation built on Sept. 11, 2024, 5:15 p.m.