[Rd] eval(parse()) within mutate() returning same value for all rows
Mateo Obregón
obregonm@teo @end|ng |rom gm@||@com
Fri Dec 29 15:13:42 CET 2023
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
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?
Mateo.
--
Mateo Obregón
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