[R] Operator proposal: %between%

[David Winsemius]

On Sep 4, 2014, at 12:54 PM, Greg Snow wrote:

> 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.

If you are accepting feature requests I would like to see a `%btwn%` function that would accept as its second argument either a two element numeric or alpha vector or a two column matrix of with the same number of rows as the first argument. Something along these lines:


> `%btwn%` <- function(x,y) if(!is.null(dim(y))&&dim(y)[1] == length(x) ){x >= y[,1] & x < y[,2]}else{x >= y[1] & x <y[2]}
> 4 %btwn% c(2,6)
[1] TRUE

-- 
David
> 
> On Thu, Sep 4, 2014 at 8:41 AM, Torbjørn 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
>> Torbjørn Lindahl
>> 
>>        [[alternative HTML version deleted]]
>> 
>> ______________________________________________
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>> https://stat.ethz.ch/mailman/listinfo/r-help
>> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
>> and provide commented, minimal, self-contained, reproducible code.
> 
> 
> 
> -- 
> Gregory (Greg) L. Snow Ph.D.
> 538280 at gmail.com
> 
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.

David Winsemius
Alameda, CA, USA