Conditional gsub replacement

I have text data (in R) and want to replace some characters with other characters in a data frame. I thought this would be an easy task using strsplit on spaces and create a vector that can I can then use matching (%in%) which can then be pasted back together. But then I thought about punctuation. There's no space between the last word of a sentence and the punctuation at the end.

I figure there's probably a more simple way to achieve what I want than the convoluted mess that's becoming my code. I would appreciate direction with this problem.

#Character String
x <- "I like 346 ice cream cones.  They're 99 percent good!  I ate 46."

#Replacement Values Dataframe
  symbol text                     
1 "346"  "three hundred forty six"
2 "99"   "ninety nine"            
3 "46"   "forty six" 

#replacement dataframe
numDF <- 
data.frame(symbol = c("346","99", "46"),
           text = c("three hundred forty six", "ninety nine","forty six"),
           stringsAsFactors = FALSE)

Desired outcome:

[1] "I like three hundred forty six ice cream cones.  They're ninety nine percent good!  You ate forty six?")

EDIT: I originally entitled this conditional gsub because that what it seems like to me even though there is no gsub involved.

Edit Report

It wasn't exactly clear whether you really wanted to convert digits to their alpha equivalents. If so then here is a much more general strategy. There are (at least) two numeric to text conversion functions in the rhelp archives: Jim Lemon's digits2text and John Fox's numberstowords. I also switched over to gregexpr to get to a vectorized approach:

Cutting and pasting Lemon's function from the HTML found here worked out of the box:

>     m <- gregexpr("[0-9]+", x)
>     sym <- regmatches(x,m)
>     regmatches(x,m) <- digits2text(as.numeric(sym[[1]]))
illion = 0 
digilen = 3 
digitext = three hundred forty six 
[1] 6 4 3
> 
> x
[1] "I like three hundred forty six ice cream cones.  They're three hundred forty six percent good!  I ate three hundred forty six."

I needed to do some editing of the numberstowords because there were some missing linefeeds that messed up the parsing (and I include the successful version below this demonstration:

>     m <- gregexpr("[0-9]+", x)
>     sym <- regmatches(x,m)
>     regmatches(x,m) <- numbers2words(as.numeric(sym[[1]]))
> 
> x
[1] "I like three hundred forty six ice cream cones.  They're three hundred forty six percent good!  I ate three hundred forty six."

Fox's function edited from: http://tolstoy.newcastle.edu.au/R/help/05/04/2715.html

numbers2words <- function(x){

    helper <- function(x){

        digits <- rev(strsplit(as.character(x), "")[[1]])
        nDigits <- length(digits)
        if (nDigits == 1) as.vector(ones[digits])
        else if (nDigits == 2)
            if (x <= 19) as.vector(teens[digits[1]])
                else trim(paste(tens[digits[2]],


                        
                        
                            answered 2012-01-02T18:55:04.597

Conditional gsub replacement

1 Answer

Your Answer