On 15/10/2016 5:48 AM, Kaiyin Zhong wrote:> Here is the code:
>
> summary(c(1:5, NA))
> summary(c("a", NA))
>
> It seems in the firs case the number of NAs is reported, but not in the
> second.
>
> Tested with R 3.3.1 on a mac.
summary() is a generic function, so the output depends on the class of
the input. There's no special method for character vectors, so you get
the default output. Numeric vectors show more detail.
If you want a particular behaviour for character objects, just write a
summary.character method.
Here's the default:
> summary(c("a", NA))
Length Class Mode
2 character character
Here's a method and example using it:
> summary.character <- function (x, ...) { cat("this character
vector
has", sum(is.na(x)), " NA value(s)\n")}
> summary(c("a", NA))
this character vector has 1 NA value(s)
Duncan Murdoch