R help - Sep 2014 - Operator proposal: %between%

Not sure if this is the proper list to propose changes like this, if it
passes constructive criticism, it would like to have a %between% operator
in the R language.

I currently have this in my local R startup script:

`%between%` <- function(x,...) {
  y <- range( unlist(c(...)) )
  return( x >= y[1] & x =< y[2] )
}

It allows me to do things like: 5 %between c(1,10)

and also as act as an "in_range" operator:
foo %between% a.long.list.with.many.values

This may seem unnecessary, since 5 >= foo[1] && foo<= foo[2] is
also quite
short to type, but there is a mental cost to this, eg if you are deeply
focused on a complicated program flow, the %between% construct is a lot
easier to type out, and relate to, than the logically more complex
construct with && and <=/>=, at least in my experience.

-- 
mvh
Torbj?rn Lindahl

	[[alternative HTML version deleted]]

On 04/09/2014 10:41 AM, Torbj?rn Lindahl wrote:
> Not sure if this is the proper list to propose changes like this, if it
> passes constructive criticism, it would like to have a %between% operator
> in the R language.
But it appears that you do:
>
> I currently have this in my local R startup script:
>
> `%between%` <- function(x,...) {
>    y <- range( unlist(c(...)) )
>    return( x >= y[1] & x =< y[2] )
> }
>
> It allows me to do things like: 5 %between c(1,10)
>
> and also as act as an "in_range" operator:
> foo %between% a.long.list.with.many.values
So what you are asking is that someone should make this available to 
others, as well.  That seems like a reasonable thing to do, but why 
shouldn't that someone be you?
>
> This may seem unnecessary, since 5 >= foo[1] && foo<= foo[2]
is also quite
> short to type, but there is a mental cost to this, eg if you are deeply
> focused on a complicated program flow, the %between% construct is a lot
> easier to type out, and relate to, than the logically more complex
> construct with && and <=/>=, at least in my experience.
>
One problem with your definition is that it's not clear it does the 
right thing when x is a vector.  I might have a vector of lower bounds, 
and a vector of upper bounds, and want to check each element of x 
against the corresponding bound, i.e. compute

  lower <= x & x <= upper

Your %between% operator could be rewritten so that x %between% 
cbind(lower, upper) would give this result, but it doesn't do so now.   
(I'm not saying you *should* rewrite it like that, but it's something 
you should consider.)

Duncan Murdoch

The TeachingDemos package has %<% and %<=% operators for a between
style comparison.  So for your example you could write:

1 %<% 5 %<% 10

or

1 %<=% 5 %<=% 10

And these operators already work with vectors:

lb %<=% x %<% ub

and can even be further chained:

0 %<% x %<% y %<% z %<% 1  # only points where x < y and y < z
and all
between 0 and 1.

It is a little bit different syntax from yours, but would that do what you want?

If not, we could add a %between% function (expand it a bit following
Duncan's suggestion) to the TeachingDemos package if you don't want to
create your own package.

On Thu, Sep 4, 2014 at 8:41 AM, Torbj?rn Lindahl
<torbjorn.lindahl at gmail.com> wrote:
> Not sure if this is the proper list to propose changes like this, if it
> passes constructive criticism, it would like to have a %between% operator
> in the R language.
>
> I currently have this in my local R startup script:
>
> `%between%` <- function(x,...) {
>   y <- range( unlist(c(...)) )
>   return( x >= y[1] & x =< y[2] )
> }
>
> It allows me to do things like: 5 %between c(1,10)
>
> and also as act as an "in_range" operator:
> foo %between% a.long.list.with.many.values
>
> This may seem unnecessary, since 5 >= foo[1] && foo<= foo[2]
is also quite
> short to type, but there is a mental cost to this, eg if you are deeply
> focused on a complicated program flow, the %between% construct is a lot
> easier to type out, and relate to, than the logically more complex
> construct with && and <=/>=, at least in my experience.
>
> --
> mvh
> Torbj?rn Lindahl
>
>         [[alternative HTML version deleted]]
>
> ______________________________________________
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> and provide commented, minimal, self-contained, reproducible code.


-- 
Gregory (Greg) L. Snow Ph.D.
538280 at gmail.com

On Thu, Sep 4, 2014 at 10:41 AM, Torbj?rn Lindahl
<torbjorn.lindahl at gmail.com> wrote:
> Not sure if this is the proper list to propose changes like this, if it
> passes constructive criticism, it would like to have a %between% operator
> in the R language.
>
There is a between function in the data.table package.
> library(data.table)
> between
function (x, lower, upper, incbounds = TRUE)
{
    if (incbounds)
        x >= lower & x <= upper
    else x > lower & x < upper
}

and also in the tis package which works differently:
> library(tis)
> between
function (y, x1, x2)
{
    y <- unclass(y)
    x1 <- unclass(x1)
    x2 <- unclass(x2)
    small <- pmin(x1, x2)
    large <- pmax(x1, x2)
    (y >= small) & (y <= large)
}

In addition, SQL has a between operator
> library(sqldf)
> sqldf("select * from BOD where Time between 3 and 5")
  Time demand
1    3   19.0
2    4   16.0
3    5   15.6