Formatting scientific names in R

Here is a function that will take a character string in R and return an expression for fancy formatting in plots that properly italicize scientific names. The syntax for doing this is truly quite horrible, but this is how R does it.

scientific_name_formatter <- function(raw_name) {
    # strsplit returns a list but we are passing in only
    # one name so we just take the first element of the list
    words = strsplit(raw_name, ' ', fixed = TRUE)[[1]]
    # some sort of acronym or bin name, leave it alone    
    if(length(words) < 2) {                  
    } else if (length(words) > 2) {
        if (words[1] == 'Candidatus') {
            # for candidatus names, only the Candidatus part is italicised
            # name shortening it for brevity
            unitalic <- paste(words[2:length(words)], collapse = ' ')
            return(bquote(paste(italic(Ca.) ~ .(unitalic))))
        } else if (grepl('^[A-Z]+$', words[1])) {
            # If the first word is in all caps then it is an abreviation
            # so we don't want to italicize that at all
        } else {
            # assume that everything after the second word is strain name
            # which should not get italicised
            unitalic <- paste(words[3:length(words)], collapse = ' ')
            return(bquote(paste(italic(.(words[1])) ~ italic(.(words[2])) ~ .(unitalic) )))
    } else {
        return(bquote(paste(italic(.(words[1])) ~ italic(.(words[2])))))

I use it like the following in ggplot by setting the labels in scale_y_discrete.

scale_y_discrete(limits = df$organism_name, labels = sapply(df$organism_name, scientific_name_formatter ))

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