重载 &R中的运算符 [英] Overloading Ampersand & operator in R
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问题描述
I like to overload my ampersand operator with paste. So that way I can paste stuff easily. Like this:
R> "Hello" & " World"
[1] "Hello World"
And the way I achieve this is:
"&" <- function(...){paste(..., sep = "")}
This is all fine and dandy but you lose the ability to use ampersand as a natural "and" operator. What would be the best, fastest most beautiful way to overload my ampersand so that it recognizes when the inputs are logical?
TRUE & FALSE == FALSE
etc.
解决方案
You'll need to use the S3 object system in R:
`&` <- function(e1, e2) UseMethod("&", c(e1, e2))
`&.default` <- function(e1, e2) paste(e1, e2)
`&.logical` <- function(e1, e2) .Primitive("&")(e1, e2)
Now you can use &
as you would expect:
> 1 & 2
[1] "1 2"
> TRUE & FALSE
[1] FALSE
> "Hello" & "World"
[1] "Hello World"
>
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