The vec_fmt_roman() function

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).

vec_fmt_roman(num_vals)

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

#> [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"  

#> [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."   
[10] "NA"   

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