Format a vector as values in scientific notation

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

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"

Function ID

15-3

Function Introduced

v0.7.0 (Aug 25, 2022)