> a <- 1234.1415926
> n1 <- floor(log(a, 10) + 1)
> total.len <- nchar(as.character(a))
> n2 <- total.len - 1 - n1
> n1
[1] 4
> n2
[1] 7

或者可以这样，对负数也适用

> a <- -1234.1415926
> char.a <- as.character(a)
> pt <- gregexpr("[.]", char.a)[[1]][1]
> total.len <- nchar(char.a)
> n1 <- pt - 1
> n2 <- total.len - 1 - n1
> n2
[1] 7
> n1
[1] 5