Print text with subscripts (programatically) to R console

Question

I'm using R to balance some complex chemical equations and would like to print these equations including subscripts to the console as the code runs. I've seen some answers posted, most of which are related to plots or rely on pasting the subscript from another program into R scripts:

1. Subscripts in R when adding other text
2. How to literally print superscripts in R not used in labels or legends?
3. Using Subscripts and Superscripts in R console

Unicode subscript in R had some pointers that were helpful. I can get the appropriate code from this link but it doesn't allow me to programatically create the code for the character I want.

CODE

Here's a simple example equation for combustion of methane that works:

> sub2 <- '\u2082' # hard-coding unicode for '2' as a subscript
> sub4 <- '\u2084' # hard-coding unicode for '4' as a subscript
> cat(sprintf('CH%s + 2 O%s --> CO%s + 2 H%sO', sub4, sub2, sub2, sub2))
CH₄ + 2 O₂ --> CO₂ + 2 H₂O

Lengthy workaround (proof-of-concept):

desired_subscript <- 3.375
subs <- c('\u2080', '\u2081', '\u2082', '\u2083', '\u2084',
          '\u2085', '\u2086', '\u2087', '\u2088', '\u2089')

charvec <- as.character(x = desired_subscript)
lapply(0:9, function(z){
  charvec <<- gsub(pattern = z, replacement = subs[z+1], x = charvec)
  return(NULL)
})

> cat(charvec)
₃.₃₇₅

Here's what doesn't work:

replacing the last digit of the unicode string to what I want:

> cat(sub(pattern = '2', replacement = '4', x = sub2))
₂

Trying to create a unicode string:

> paste('\208','4',sep = '')
[1] "\02084"

I have multiple equations to balance and the subscripts are not always whole numbers. Is there a way to programatically get unicode for the subscript that I want to include in my output to console?

Answer 1

Try this

create a function to return unicodes. Caution: No error checking

ss <- function(x) {intToUtf8(0x2080 + x)}

cat(sprintf('CH%s + 2 O%s --> CO%s + 2 H%sO', ss(4), ss(2), ss(2), ss(2)))