I am looking at codes in odf formulas that look a bit like this:
{500mgl} over {4.05grams}
I want to use a regex with gsub in R to enclose in brackets all of the elements with the pattern
([0-9]+)([A-Za-z]+)
to avoid some units not displaying in the denominator. However, if I do this, the respective units will end up separated from the real number: 4,{0.5g} So what I want to enclose first the numbers with the commas:
a<-"4,05g"
gsub("([0-9]+)(\\,)([0-9]+)([A-Za-z]+)","{\\1\\2\\3\\4}",a)
and then, enclose with brackets the pattern:
([0-9]+)([A-Za-z]+)
but only if there is not an opening bracket before the pattern. I've tried searching the web for how look back syntax works with regex, however, I get pretty confused with how it works within R's gsub. I tried things like this:
gsub("([^\\.])([0-9]+)([A-Za-z]+)","{\\2\\3}",a)
gsub("(?[\\.])([0-9]+)([A-Za-z]+)","{\\2\\3}",a)
gsub("(!\\.?)([0-9]+)([A-Za-z]+)","{\\2\\3}",a)
but honestly I have no idea what I'm doing.
EDIT: I think that the exemption for the previous character must be not a bracket but a comma. That way one would avoid the output
"0,3g
" 0,{3g}"
but be able to do
"30g"
"{30g}"
