cells_summary: Location helper for targeting group summary cells

Description

The cells_summary() function is used to target the cells in a group summary and it is useful when applying a footnote with tab_footnote() or adding a custom style with tab_style(). The function is expressly used in each of those functions' locations argument. The 'summary' location is generated by the summary_rows() function.

Usage

cells_summary(
  groups = everything(),
  columns = everything(),
  rows = everything()
)

Value

A list object with the classes cells_summary and location_cells.

Arguments

groups: The names of the groups that the summary rows reside in.
columns: The names of the columns that are to be targeted.
rows: The names of the rows that are to be targeted.

Targeting cells with <code>columns</code>, <code>rows</code>, and <code>groups</code>

Targeting of summary cells is done through the groups, columns, and rows arguments. By default groups is set to everything(), which means that all available groups will be considered. Providing the ID values (in quotes) of row groups in c() will serve to constrain the targeting to that subset of groups.

The columns argument allows us to target a subset of summary 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).

Once the groups and columns are targeted, we may also target the rows of the summary. Summary cells in the stub will have ID values that 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)) that correspond to the row number of a summary row in a row group (numbering restarts with every row group).

Overview of location helper functions

Location helper functions can be used to target cells with virtually any function that has a locations argument. Here is a listing of all of the location helper functions, with locations corresponding roughly from top to bottom of a table:

cells_title(): targets the table title or the table subtitle depending on the value given to the groups argument ("title" or "subtitle").
cells_stubhead(): targets the stubhead location, a cell of which is only available when there is a stub; a label in that location can be created by using the tab_stubhead() function.
cells_column_spanners(): targets the spanner column labels with the spanners argument; spanner column labels appear above the column labels.
cells_column_labels(): targets the column labels with its columns argument.
cells_row_groups(): targets the row group labels in any available row groups using the groups argument.
cells_stub(): targets row labels in the table stub using the rows argument.
cells_body(): targets data cells in the table body using intersections of columns and rows.
cells_summary(): targets summary cells in the table body using the groups argument and intersections of columns and rows.
cells_grand_summary(): targets cells of the table's grand summary using intersections of columns and rows
cells_stub_summary(): targets summary row labels in the table stub using the groups and rows arguments.
cells_stub_grand_summary(): targets grand summary row labels in the table stub using the rows argument.
cells_footnotes(): targets all footnotes in the table footer (cannot be used with tab_footnote()).
cells_source_notes(): targets all source notes in the table footer (cannot be used with tab_footnote()).

When using any of the location helper functions with an appropriate function that has a locations argument (e.g., tab_style()), multiple locations can be targeted by enclosing several cells_*() helper functions in a list() (e.g., list(cells_body(), cells_grand_summary())).

Examples

Use countrypops to create a gt table. Add some styling to the summary data cells with with tab_style(), using cells_summary() in locations.

countrypops |>
  dplyr::filter(country_name == "Japan", year < 1970) |>
  dplyr::select(-contains("country")) |>
  dplyr::mutate(decade = paste0(substr(year, 1, 3), "0s")) |>
  gt(
    rowname_col = "year",
    groupname_col = "decade"
  ) |>
  fmt_number(
    columns = population,
    decimals = 0
  ) |>
  summary_rows(
    groups = "1960s",
    columns = population,
    fns = list("min", "max"),
    fmt = ~ fmt_integer(.)
  ) |>
  tab_style(
    style = list(
      cell_text(style = "italic"),
      cell_fill(color = "lightblue")
    ),
    locations = cells_summary(
      groups = "1960s",
      columns = population,
      rows = 1
    )
  ) |>
  tab_style(
    style = list(
      cell_text(style = "italic"),
      cell_fill(color = "lightgreen")
    ),
    locations = cells_summary(
      groups = "1960s",
      columns = population,
      rows = 2
    )
  )

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

Function ID

8-13

Function Introduced

v0.2.0.5 (March 31, 2020)