受教了！

好高端！

stringr package could manage this
for instance:

fruit <- c("23%","5%","121%","-52%","55%")
str_extract(fruit,"[1-99]+%")
str_extract(fruit,"[1-9]+|-[1-9]+")

you'll see what you want

Cheers,

Sorry, it should be 0-9 or 0-99.  :P