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Related: Convert roman numerals to numbers in R

In the above question, an answer states that there is a function utils:::.roman2numeric() to convert roman to numeric. I also found out that there is a similar function to convert numeric to roman: utils:::.numeric2roman(). Unfortunately it does not work for some numbers, why?

E.g. 3978, 3985 produces NA

This is similar to how as.roman() doesn't work for some roman numbers converting to numerics. E.g. MMMCMXI gives NA instead of 3911.

Is there another function that works for numeric to roman 100% of the time? (Best if it's builtin)

Bonus: another function that works, other than utils:::.roman2numeric(), for roman to numeric. (as.roman() does not work as explained earlier).

DialFrost
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1 Answers1

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From the help page ?utils::as.roman:

Only numbers between 1 and 3899 have a unique representation as roman numbers, and hence others result in as.roman(NA).

Here is a function that claims to convert larger numeric values to Roman.

For the other direction you could try gtools::roman2int.

neilfws
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