chemSymWords

There seems to be a fad right now of merchandising articles containing words made up of chemical symbols. Beryllium Erbium (BeEr) is particularly popular and I have to admit I have a T-Shirt claiming “Call me NErDy”. I’ve put together a small code in R which will check to see if a word can be created purely by element symbols and then output a PNG.

The algorithm to turn a word into symbols is fairly straightforward and involves a little recursion. The recursive function is shown below. It comprises of an outer function (chemwordRecurse) and an inner one chemwordRecurseInternal. The output variable (a list) is initialized in the outer function and utilized within the inner one. This allows a single output to be updated which can be a problem when recursion traverses a tree-like pathway as there could be multiple instances of the output. Recall is a way to recursively call using a placeholder as opposed to specifying the function name.

chemWordRecurse <- function(w, t, sym=elements) {
  out <- list()

  chemWordRecurseInternal <- function(w, t, sym) {
    if (nchar(w) == 0) {
      out[[length(out) + 1]] <<- unlist(t)
    }
    for (i in 1:min(max(nchar(sym)), nchar(w))) {
      find_el <- match(toupper(substring(w, 1, i)),toupper(sym))
      if (!is.na(find_el)) {
        Recall(substring(w, i + 1), c(t, find_el), sym)
      }
    }
  }
  chemWordRecurseInternal(w, t, sym)
  return(out)
}

An old stackexchange thread (http://puzzling.stackexchange.com/questions/5456/the-longest-word-made-from-chemical-symbols) challenges the longest word which can be made out of chemical symbols. At the time of this writing it’s Floccinaucinihilipilifications at 30 letters.

The code can be found at https://github.com/harveyl888/chemSymWords