With numeric values in a vector, we can perform formatting so that the targeted values are rendered in scientific notation, where extremely large or very small numbers can be expressed in a more practical fashion. Here, numbers are written in the form of a mantissa (`m`) and an exponent (`n`) with the construction m x 10^n or mEn. The mantissa component is a number between `1` and `10`. For instance, `2.5 x 10^9` can be used to represent the value 2,500,000,000 in scientific notation. In a similar way, 0.00000012 can be expressed as `1.2 x 10^-7`. Due to its ability to describe numbers more succinctly and its ease of calculation, scientific notation is widely employed in scientific and technical domains.

We have fine control over the formatting task, with the following options:

• decimals: choice of the number of decimal places, option to drop trailing zeros, and a choice of the decimal symbol

• scaling: we can choose to scale targeted values by a multiplier value

• pattern: option to use a text pattern for decoration of the formatted values

• locale-based formatting: providing a locale ID will result in formatting specific to the chosen locale

## Usage

``````vec_fmt_scientific(
x,
decimals = 2,
n_sigfig = NULL,
drop_trailing_zeros = FALSE,
drop_trailing_dec_mark = TRUE,
scale_by = 1,
exp_style = "x10n",
pattern = "{x}",
sep_mark = ",",
dec_mark = ".",
force_sign_m = FALSE,
force_sign_n = FALSE,
locale = NULL,
output = c("auto", "plain", "html", "latex", "rtf", "word")
)``````

## Arguments

x

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.

decimals

Number of decimal places

`scalar<numeric|integer>(val>=0)` // default: `2`

This corresponds to the exact number of decimal places to use. A value such as `2.34` can, for example, be formatted with `0` decimal places and it would result in `"2"`. With `4` decimal places, the formatted value becomes `"2.3400"`.

n_sigfig

Number of significant figures

`scalar<numeric|integer>(val>=1)` // default: `NULL` (`optional`)

A option to format numbers to n significant figures. By default, this is `NULL` and thus number values will be formatted according to the number of decimal places set via `decimals`. If opting to format according to the rules of significant figures, `n_sigfig` must be a number greater than or equal to `1`. Any values passed to the `decimals` and `drop_trailing_zeros` arguments will be ignored.

drop_trailing_zeros

Drop any trailing zeros

`scalar<logical>` // default: `FALSE`

A logical value that allows for removal of trailing zeros (those redundant zeros after the decimal mark).

drop_trailing_dec_mark

Drop the trailing decimal mark

`scalar<logical>` // default: `TRUE`

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.` if `FALSE`). By default trailing decimal marks are not shown.

scale_by

Scale values by a fixed multiplier

`scalar<numeric|integer>` // default: `1`

All numeric values will be multiplied by the `scale_by` value before undergoing formatting. Since the `default` value is `1`, no values will be changed unless a different multiplier value is supplied.

exp_style

Style declaration for exponent formatting

`scalar<character>` // default: `"x10n"`

Style of formatting to use for the scientific notation formatting. By default this is `"x10n"` but other options include using a single letter (e.g., `"e"`, `"E"`, etc.), a letter followed by a `"1"` to signal a minimum digit width of one, or `"low-ten"` for using a stylized `"10"` marker.

pattern

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.

sep_mark

Separator mark for digit grouping

`scalar<character>` // default: `","`

The string to use as a separator between groups of digits. For example, using `sep_mark = ","` with a value of `1000` would result in a formatted value of `"1,000"`. This argument is ignored if a `locale` is supplied (i.e., is not `NULL`).

dec_mark

Decimal mark

`scalar<character>` // default: `"."`

The string to be used as the decimal mark. For example, using `dec_mark = ","` with the value `0.152` would result in a formatted value of `"0,152"`). This argument is ignored if a `locale` is supplied (i.e., is not `NULL`).

force_sign_m, force_sign_n

Forcing the display of a positive sign

`scalar<logical>` // default: `FALSE`

Should the plus sign be shown for positive values of the mantissa (first component, `force_sign_m`) or the exponent (`force_sign_n`)? This would effectively show a sign for all values except zero on either of those numeric components of the notation. If so, use `TRUE` for either one of these options. The default for both is `FALSE`, where only negative numbers will display a sign.

locale

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 call `info_locales()` for a useful reference for all of the locales that are supported.

output

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

## Value

A character vector.

## Examples

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

``num_vals <- c(3.24e-4, 8.65, 1362902.2, -59027.3, NA)``

Using `vec_fmt_scientific()` with the default options will create a character vector with values in scientific notation. Any `NA` values remain as `NA` values. The rendering context will be autodetected unless specified in the `output` argument (here, it is of the `"plain"` output type).

``vec_fmt_scientific(num_vals)``

``#> [1] "3.24 x 10^-4" "8.65" "1.36 x 10^6" "-5.90 x 10^4" "NA"``

We can change the number of decimal places with the `decimals` option:

``vec_fmt_scientific(num_vals, decimals = 1)``

``#> [1] "3.2 x 10^-4" "8.7" "1.4 x 10^6" "-5.9 x 10^4" "NA"``

If we are formatting for a different locale, we could supply the locale ID and gt will handle any locale-specific formatting options:

``vec_fmt_scientific(num_vals, locale = "es")``

``#> [1] "3,24 x 10^-4" "8,65" "1,36 x 10^6" "-5,90 x 10^4" "NA"``

Should you need to have positive and negative signs for the mantissa component of a given value, use `force_sign_m = TRUE`:

``vec_fmt_scientific(num_vals, force_sign_m = TRUE)``

``#> [1] "+3.24 x 10^-4" "+8.65" "+1.36 x 10^6" "-5.90 x 10^4" "NA"``

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_scientific(num_vals, pattern = "[{x}]")``

``#> [1] "[3.24 x 10^-4]" "[8.65]" "[1.36 x 10^6]" "[-5.90 x 10^4]" "NA"``

15-3

## Function Introduced

`v0.7.0` (Aug 25, 2022)

The variant function intended for formatting gt table data: `fmt_scientific()`.
Other vector formatting functions: `vec_fmt_bytes()`, `vec_fmt_currency()`, `vec_fmt_date()`, `vec_fmt_datetime()`, `vec_fmt_duration()`, `vec_fmt_engineering()`, `vec_fmt_fraction()`, `vec_fmt_index()`, `vec_fmt_integer()`, `vec_fmt_markdown()`, `vec_fmt_number()`, `vec_fmt_partsper()`, `vec_fmt_percent()`, `vec_fmt_roman()`, `vec_fmt_spelled_num()`, `vec_fmt_time()`