# Plus-equals

Found this on Twitter.

This hack works for other operators as well, like `+<-`

, `-<-`

and even `!<-`

. This made me come up with an idea of two Python-like operators for increasing/decreasing scalars/concatenating vectors:

```
`+<-` = function(x, value) {
if (length(x) > 1) c(x, value) else x + value
}
`-<-` = function(x, value) {
if (length(x) > 1) x[x != value] else x - value
}
# Some examples:
x = 5
+x = 7
print(x) # [1] 12
-x = 15
print(x) # [1] -3
y = c(1, 3, 5)
+y = 7
print(y) # [1] 1 3 5 7
-y = 1
print(y) # [1] 3 5 7
```

They are not really reliable (you need to know the length of the input variable before the operation or else the result may be a surprise to you), but it’s amusing, isn’t it?

[UPDATE]

This is even more impressive:

```
# A logical function
even = function(x) { x %% 2 == 0 }
`%is%<-` = function(x, fun, value) {
ifelse(fun(x), value, x)
}
x = 1:10
x %is% even = NA
print(x) # [1] 1 NA 3 NA 5 NA 7 NA 9 NA
```

(Inspired by this article)