hi, I practice R programing by the step in <<R In Action>>;
when i test by function, i get error like these;
call for help!
dstats <- function(x){c(mean=mean(x), sd=sd(x))}
> by(mtcars[,c('mpg', 'hp')], mtcars$am, dstats)
Show Traceback
Rerun with Debug
Error in is.data.frame(x) :
(list) object cannot be coerced to type 'double'
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BestRegards
Su Wenlong
Phone:13408010439
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