R: Relabel columns with a function

cols_label_with {gt}

R Documentation

Relabel columns with a function

Description

Column labels can be modified from their default values (the names of the columns from the input table data). When you create a gt table object using gt(), column names effectively become the column labels. While this serves as a good first approximation, you may want to make adjustments so that the columns names present better in the gt output table. The cols_label_with() function allows for modification of column labels through a supplied function. By default, the function will be invoked on all column labels but this can be limited to a subset via the columns argument. With the fn argument, we provide either a bare function name, a RHS formula (with . representing the vector of column labels), or, an anonymous function (e.g., function(x) tools::toTitleCase(x)).

Usage

cols_label_with(data, columns = everything(), fn)

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.

columns

Columns to target

⁠<column-targeting expression>⁠ // default: everything()

The columns for which the column-labeling operations should be applied. 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()).

fn

Function to apply

⁠function|formula⁠ // required

The function or function call to be applied to the column labels. This can take the form of a bare function (e.g., tools::toTitleCase), a function call as a RHS formula (e.g., ~ tools::toTitleCase(.)), or an anonymous function as in function(x) tools::toTitleCase(x).

Value

An object of class gt_tbl.

A note on column names and column labels

It's important to note that while columns can be freely relabeled, we continue to refer to columns by their original column names. Column names in a tibble or data frame must be unique whereas column labels in gt have no requirement for uniqueness (which is useful for labeling columns as, say, measurement units that may be repeated several times—usually under different spanner labels). Thus, we can still easily distinguish between columns in other gt function calls (e.g., in all of the ⁠fmt*()⁠ functions) even though we may lose distinguishability in column labels once they have been relabeled.

Examples

Use a subset of the sp500 dataset to create a gt table. We want all the column labels to be entirely capitalized versions of the default labels but, instead of using cols_label() and rewriting each label manually in capital letters we can use cols_label_with() and instruct it to apply the toupper() function to all column labels.

sp500 |>
  dplyr::filter(
    date >= "2015-12-01" &
      date <= "2015-12-15"
  ) |>
  dplyr::select(-c(adj_close, volume)) |>
  gt() |>
  cols_label_with(fn = toupper)

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

Use the countrypops dataset to create a gt table. To improve the presentation of the table, we are again going to change the default column labels via function calls supplied within cols_label_with(). We can, if we prefer, apply multiple types of column label changes in sequence with multiple calls of cols_label_with(). Here, we use the make_clean_names() functions from the janitor package and follow up with the removal of a numeral with gsub().

countrypops |>
  dplyr::filter(year == 2021) |>
  dplyr::filter(grepl("^C", country_code_3)) |>
  dplyr::select(-country_code_2, -year) |>
  head(8) |>
  gt() |>
  cols_move_to_start(columns = country_code_3) |>
  fmt_integer(columns = population) |>
  cols_label_with(
    fn = ~ janitor::make_clean_names(., case = "title")
  ) |>
  cols_label_with(
    fn = ~ gsub("[0-9]", "", .)
  )

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

We can make a svelte gt table with the pizzaplace dataset. There are ways to use one instance of cols_label_with() with multiple functions called on the column labels. In the example, we use an anonymous function call (with the function(x) { ... } construction) to perform multiple mutations of x (the vector of column labels). We can even use the md() helper function with that to signal to gt that the column label should be interpreted as Markdown text.

pizzaplace |>
  dplyr::mutate(month = substr(date, 6, 7)) |>
  dplyr::group_by(month) |>
  dplyr::summarize(pizze_vendute = dplyr::n()) |>
  dplyr::ungroup() |>
  dplyr::mutate(frazione_della_quota = pizze_vendute / 4000) |>
  dplyr::mutate(date = paste0("2015/", month, "/01")) |>
  dplyr::select(-month) |>
  gt(rowname_col = "date") |>
  fmt_date(date, date_style = "month", locale = "it") |>
  fmt_percent(columns = frazione_della_quota) |>
  fmt_integer(columns = pizze_vendute) |>
  cols_width(everything() ~ px(100)) |>
  cols_label_with(
    fn = function(x) {
      janitor::make_clean_names(x, case = "title") |>
        toupper() |>
        stringr::str_replace_all("^|$", "**") |>
        md()
    }
  )

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

Function ID

5-5

Function Introduced

v0.9.0 (March 31, 2023)