'+' operator to support non numeric arguments in r

Question

The "+" supports numeric, integer and Date in r. All below operations are valid.

> 5 + 5L
[1] 10
> Sys.Date() + 5
[1] "2018-01-18"

But + doesn't work between character. Like:

> "one" + "one"
Error in "one" + "one" : non-numeric argument to binary operator
> "What is date today? Ans:" + Sys.Date()
Error in unclass(e1) + unclass(e2) : 
  non-numeric argument to binary operator

Is it forbidden to allow other than numeric argument in r? Or someone can overwrite + behavior to support other types of argument.

@Carcigenicate I was looking for substitute of `paste`. That means, I was expecting `"oneone"`. — MKR, Jan 13 '18 at 19:49
Why is this behaviour inconsistent? What do you expect `"one"+"two"` to deliver? It just is not defined for character arguments. — Bhas, Jan 13 '18 at 19:49
@MKR Oh, so string concatenation. R creators seem to have chosen for `+` to he used solely for numeric uses. Doesn't seem inconsistent. — Carcigenicate, Jan 13 '18 at 19:51
@Bhas Yes. `paste` is available but sometime I miss that capability. esp. while using from command line in `RStudio`. — MKR, Jan 13 '18 at 19:52
@Carcigenicate Agree. Title of issue is not appropriate. There is no consistency. Rather I'm looking for additional feature. — MKR, Jan 13 '18 at 19:53
@RichScriven Thanks Rich. It seems solution from `aocall` is more elegant. — MKR, Jan 13 '18 at 20:07
... which is also the same as [this answer](https://stackoverflow.com/questions/4730551/making-a-string-concatenation-operator-in-r/30649288#30649288) on that question. — Rich Scriven, Jan 13 '18 at 20:09
@RichScriven yes. I should have done some more research before asking it. Thanks again. — MKR, Jan 13 '18 at 20:11

score 7 · Accepted Answer · answered Jan 13 '18 at 20:02

7

You could redefine +, though I don't recommend it.

`+` <- function(x, y) UseMethod("+")
`+.character` <- function(x, y) paste0(x, y)
`+.default` <- .Primitive("+")

1 + 1 ##2
"a" + "b" ##"ab"
"a" + 2 ##"a2"

answered Jan 13 '18 at 20:02

alan ocallaghan

3,044
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I do wonder why R's core team never added it to R itself... – Tal Galili Nov 19 '19 at 16:51

'+' operator to support non numeric arguments in r

1 Answers1