fmt_currency: Format values as currencies

Description

With numeric values in a gt table, we can perform currency-based formatting. This function supports both automatic formatting with a three-letter or numeric currency code. We can also specify a custom currency that is formatted according to the output context with the currency() helper function. Numeric formatting facilitated through the use of a locale ID. We have fine control over the conversion from numeric values to currency values, where we could take advantage of the following options:

the currency: providing a currency code or common currency name will procure the correct currency symbol and number of currency subunits; we could also use the currency() helper function to specify a custom currency
currency symbol placement: the currency symbol can be placed before or after the values
decimals/subunits: choice of the number of decimal places, and a choice of the decimal symbol, and an option on whether to include or exclude the currency subunits (decimal portion)
negative values: choice of a negative sign or parentheses for values less than zero
digit grouping separators: options to enable/disable digit separators and provide a choice of separator symbol
scaling: we can choose to scale targeted values by a multiplier value
large-number suffixing: larger figures (thousands, millions, etc.) can be autoscaled and decorated with the appropriate suffixes
pattern: option to use a text pattern for decoration of the formatted currency values
locale-based formatting: providing a locale ID will result in currency formatting specific to the chosen locale

We can use the info_currencies() function for a useful reference on all of the possible inputs to the currency argument.

Usage

fmt_currency(
  data,
  columns = everything(),
  rows = everything(),
  currency = "USD",
  use_subunits = TRUE,
  decimals = NULL,
  drop_trailing_dec_mark = TRUE,
  use_seps = TRUE,
  accounting = FALSE,
  scale_by = 1,
  suffixing = FALSE,
  pattern = "{x}",
  sep_mark = ",",
  dec_mark = ".",
  force_sign = FALSE,
  placement = "left",
  incl_space = FALSE,
  system = c("intl", "ind"),
  locale = NULL
)

Value

An object of class gt_tbl.

Arguments

data

A table object that is created using the gt() function.

columns

The columns to format. 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 to format. Providing everything() (the default) results in all rows in columns being formatted. 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).

currency

The currency to use for the numeric value. This input can be supplied as a 3-letter currency code (e.g., "USD" for U.S. Dollars, "EUR" for the Euro currency). Use info_currencies() to get an information table with all of the valid currency codes and examples of each. Alternatively, we can provide a common currency name (e.g., "dollar", "pound", "yen", etc.) to simplify the process. Use info_currencies() with the type == "symbol" option to view an information table with all of the supported currency symbol names along with examples.

We can also use the currency() helper function to specify a custom currency, where the string could vary across output contexts. For example, using currency(html = "&fnof;", default = "f") would give us a suitable glyph for the Dutch guilder in an HTML output table, and it would simply be the letter "f" in all other output contexts). Please note that decimals will default to 2 when using the currency() helper function.

If nothing is provided to currency then "USD" (U.S. dollars) will be used.

use_subunits

An option for whether the subunits portion of a currency value should be displayed. By default, this is TRUE.

decimals

An option to specify the exact number of decimal places to use. The default number of decimal places is 2.

drop_trailing_dec_mark

A logical value that determines whether decimal marks should always appear even if there are no decimal digits to display after formatting (e.g, 23 becomes 23.). The default for this is TRUE, which means that trailing decimal marks are not shown.

use_seps

An option to use digit group separators. The type of digit group separator is set by sep_mark and overridden if a locale ID is provided to locale. This setting is TRUE by default.

accounting

An option to use accounting style for values. With FALSE (the default), negative values will be shown with a minus sign. Using accounting = TRUE will put negative values in parentheses.

scale_by

A value to scale the input. The default is 1.0. All numeric values will be multiplied by this value first before undergoing formatting. This value will be ignored if using any of the suffixing options (i.e., where suffixing is not set to FALSE).

suffixing

An option to scale and apply suffixes to larger numbers (e.g., 1924000 can be transformed to 1.92M). This option can accept a logical value, where FALSE (the default) will not perform this transformation and TRUE will apply thousands (K), millions (M), billions (B), and trillions (T) suffixes after automatic value scaling. We can also specify which symbols to use for each of the value ranges by using a character vector of the preferred symbols to replace the defaults (e.g., c("k", "Ml", "Bn", "Tr")).

Including NA values in the vector will ensure that the particular range will either not be included in the transformation (e.g, c(NA, "M", "B", "T") won't modify numbers in the thousands range) or the range will inherit a previous suffix (e.g., with c("K", "M", NA, "T"), all numbers in the range of millions and billions will be in terms of millions).

Any use of suffixing (where it is not set expressly as FALSE) means that any value provided to scale_by will be ignored.

If using system = "ind" then the default suffix set provided by suffixing = TRUE will be c(NA, "L", "Cr"). This doesn't apply suffixes to the thousands range, but does express values in lakhs and crores.

pattern

A formatting pattern that allows for decoration of the formatted value. The value itself is represented by {x} and all other characters are taken to be string literals.

sep_mark

The mark to use as a separator between groups of digits (e.g., using sep_mark = "," with 1000 would result in a formatted value of 1,000).

dec_mark

The character to use as a decimal mark (e.g., using dec_mark = "," with 0.152 would result in a formatted value of 0,152).

force_sign

Should the positive sign be shown for positive values (effectively showing a sign for all values except zero)? If so, use TRUE for this option. The default is FALSE, where only negative numbers will display a minus sign. This option is disregarded when using accounting notation with accounting = TRUE.

placement

The placement of the currency symbol. This can be either be left (the default) or right.

incl_space

An option for whether to include a space between the value and the currency symbol. The default is to not introduce a space character.

system

The numbering system to use. By default, this is the international numbering system ("intl") whereby grouping separators (i.e., sep_mark) are separated by three digits. The alternative system, the Indian numbering system ("ind") uses grouping separators that correspond to thousand, lakh, crore, and higher quantities.

locale

An optional locale identifier that can be used for formatting the value according the locale's rules. Examples include "en" for English (United States) and "fr" for French (France). The use of a locale ID will override any locale-specific values provided. We can use the info_locales() function as a useful reference for all of the locales that are supported.

Compatibility of formatting function with data values

The fmt_currency() formatting function is compatible with body cells that are of the "numeric" or "integer" types. Any other types of body cells are ignored during formatting. This is to say that cells of incompatible data types may be targeted, but there will be no attempt to format them.

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

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 target 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 formatting function will be skipped over, like character values and numeric fmt_*() functions. So it's safe to select all columns with a particular formatting function (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. This is nice if you want to base formatting on values in the column or another column, or, you'd like to use a more complex predicate expression.

Adapting output to a specific <code>locale</code>

This formatting function can adapt outputs according to a provided locale value. Examples include "en" for English (United States) and "fr" for French (France). The use of a valid locale ID here means separator and decimal marks will be correct for the given locale. Should any values be provided in sep_mark or dec_mark, they will be overridden by the locale's preferred values.

Note that a locale value provided here will override any global locale setting performed in gt()'s own locale argument (it is settable there as a value received by all other functions that have a locale argument). As a useful reference on which locales are supported, we can use the info_locales() function to view an info table.

Examples

Use exibble to create a gt table. Format the currency column to have currency values in euros ("EUR").

exibble |>
  gt() |>
  fmt_currency(
    columns = currency,
    currency = "EUR"
  )

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

Use exibble to create a gt table. Keep only the num and currency, columns, then, format those columns using the "CNY" and "GBP" currencies.

exibble |>
  dplyr::select(num, currency) |>
  gt() |>
  fmt_currency(
    columns = num,
    currency = "CNY"
  ) |>
  fmt_currency(
    columns = currency,
    currency = "GBP"
  )

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

Function ID

3-8

Function Introduced

v0.2.0.5 (March 31, 2020)