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With numeric values in a vector, we can transform those to Roman numerals, rounding values as necessary.


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



A numeric vector.


Should Roman numerals should be rendered as uppercase ("upper") or lowercase ("lower") letters? By default, this is set to "upper".


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.


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, 0, -5, 1.3, NA)

Using vec_fmt_roman() with the default options will create a character vector with values rendered as Roman numerals. Zero values will be rendered as "N", any NA values remain as NA values, negative values will be automatically made positive, and values greater than or equal to 3900 will be rendered as "ex terminis". The rendering context will be autodetected unless specified in the output argument (here, it is of the "plain" output type).


#> [1] "I" "IV" "V" "VIII" "XII" "XX" "N" "V" "I" "NA"

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

vec_fmt_roman(num_vals, case = "lower")

#> [1] "i" "iv" "v" "viii" "xii" "xx" "n" "v" "i" "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_roman(num_vals, case = "lower", pattern = "{x}.")

#> [1] "i." "iv." "v." "viii." "xii." "xx." "n." "v." "i." "NA"

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