vec_fmt_index: Format a vector as indexed characters

View source: R/format_vec.R

vec_fmt_indexR Documentation

Format a vector as indexed characters


With numeric values in a vector, we can transform those to index values, usually based on letters. These characters can be derived from a specified locale and they are intended for ordering (often leaving out characters with diacritical marks).


  case = c("upper", "lower"),
  index_algo = c("repeat", "excel"),
  pattern = "{x}",
  locale = NULL,
  output = c("auto", "plain", "html", "latex", "rtf", "word")



The input vector

vector(numeric|integer) // required

This is the input vector that will undergo transformation to a character vector of the same length. Values within the vector will be formatted.


Use uppercase or lowercase letters

⁠singl-kw:[upper|lower]⁠ // default: "upper"

Should the resulting index characters be rendered as uppercase ("upper") or lowercase ("lower") letters? By default, this is set to "upper".


Indexing algorithm

⁠singl-kw:[repeat|excel]⁠ // default: "repeat"

The indexing algorithm handles the recycling of the index character set. By default, the "repeat" option is used where characters are doubled, tripled, and so on, when moving past the character set limit. The alternative is the "excel" option, where Excel-based column naming is adapted and used here (e.g., ⁠[..., Y, Z, AA, AB, ...]⁠).


Specification of the formatting pattern

⁠scalar<character>⁠ // default: "{x}"

A formatting pattern that allows for decoration of the formatted value. The formatted value is represented by the {x} (which can be used multiple times, if needed) and all other characters will be interpreted as string literals.


Locale identifier

⁠scalar<character>⁠ // default: NULL (optional)

An optional locale identifier that can be used for formatting values according the locale's rules. Examples include "en" for English (United States) and "fr" for French (France). We can use the info_locales() function as a useful reference for all of the locales that are supported. A locale ID can be also set in the initial gt() function call (where it would be used automatically by any function with a locale argument) but a locale value provided here will override that global locale.


Output format

⁠singl-kw:[auto|plain|html|latex|rtf|word]⁠ // default: "auto"

The output style of the resulting character vector. This can either be "auto" (the default), "plain", "html", "latex", "rtf", or "word". In knitr rendering (i.e., Quarto or R Markdown), the "auto" option will choose the correct output value


A character vector.


Let's create a numeric vector for the next few examples:

num_vals <- c(1, 4, 5, 8, 12, 20, 26, 34, 0, -5, 1.3, NA)

Using vec_fmt_index() with the default options will create a character vector with values rendered as index numerals. Zero values will be rendered as "" (i.e., empty strings), any NA values remain as NA values, and negative values will be automatically made positive. The rendering context will be autodetected unless specified in the output argument (here, it is of the "plain" output type).

#> [1] "A" "D" "E" "H" "L" "T" "Z" "HH" "" "E" "A" "NA"

We can also use vec_fmt_index() with the case = "lower" option to create a character vector with values rendered as lowercase Roman numerals.

vec_fmt_index(num_vals, case = "lower")
#> [1] "a" "d" "e" "h" "l" "t" "z" "hh" "" "e" "a" "NA"

If we are formatting for a different locale, we could supply the locale ID and let gt obtain a locale-specific set of index values:

vec_fmt_index(1:10, locale = "so")
#> [1] "B" "C" "D" "F" "G" "H" "J" "K" "L" "M"

As a last example, one can wrap the values in a pattern with the pattern argument. Note here that NA values won't have the pattern applied.

vec_fmt_index(num_vals, case = "lower", pattern = "{x}.")
#> [1] "a." "d." "e." "h." "l." "t." "z." "hh." "." "e." "a." "NA"

Function ID


Function Introduced

v0.9.0 (Mar 31, 2023)

See Also

The variant function intended for formatting gt table data: fmt_index().

Other vector formatting functions: vec_fmt_bytes(), vec_fmt_currency(), vec_fmt_datetime(), vec_fmt_date(), vec_fmt_duration(), vec_fmt_engineering(), vec_fmt_fraction(), vec_fmt_integer(), vec_fmt_markdown(), vec_fmt_number(), vec_fmt_partsper(), vec_fmt_percent(), vec_fmt_roman(), vec_fmt_scientific(), vec_fmt_spelled_num(), vec_fmt_time()

gt documentation built on June 22, 2024, 11:11 a.m.