On 29 December 2023 at 14:13, Mateo Obregón wrote:
| Hi all-
|
| Looking through stackoverflow for R string combining examples, I found the
| following from 3 years ago:
|
|
<https://stackoverflow.com/questions/63881854/how-to-format-strings-using-values-from-other-column-in-r>
|
| The top answer suggests to use eval(parse(sprintf())). I tried the suggestion
Well:
> fortunes::fortune(106)
If the answer is parse() you should usually rethink the question.
-- Thomas Lumley
R-help (February 2005)
>
| and it did not return the expected combines strings. I thought that this
might
| be an issue with some leftover values being reused, so I explicitly eval()
| with a new.env():
|
| > library(dplyr)
| > df <- tibble(words=c("%s plus %s equals %s"),
| args=c("1,1,2","2,2,4","3,3,6"))
| > df |> mutate(combined = eval(parse(text=sprintf("sprintf('%s', %s)", words,
| args)), envir=new.env()))
|
| # A tibble: 3 × 3
| words args combined
| <chr> <chr> <chr>
| 1 %s plus %s equals %s 1,1,2 3 plus 3 equals 6
| 2 %s plus %s equals %s 2,2,4 3 plus 3 equals 6
| 3 %s plus %s equals %s 3,3,6 3 plus 3 equals 6
|
| The `combined` is not what I was expecting, as the same last eval() is
| returned for all three rows.
|
| Am I missing something? What has changed in the past three years?
Nothing if you use the first answer which relies only on base R and still
works:
> words <- c('%s + %s equal %s', '%s + %s equal %s')
> arguments <- c('1,1,2', '2,2,4')
> df <- data.frame(words, arguments)
> df
words arguments
1 %s + %s equal %s 1,1,2
2 %s + %s equal %s 2,2,4
> df$combined <- apply(df, 1, function(x) do.call(sprintf,
c(as.list(strsplit(x[2], ',')[[1]]), fmt = x[[1]])))
> df
words arguments combined
1 %s + %s equal %s 1,1,2 1 + 1 equal 2
2 %s + %s equal %s 2,2,4 2 + 2 equal 4
>
I am not the best person to answer what may have changed in `dplyr` in those
three years -- and neither is this list which is primarily concerned with
developing R itself.
Dirk
--
dirk.eddelbuettel.com | @eddelbuettel | e...@debian.org
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