[R] questions on some operators in R

Joshua Wiley jwiley.psych at gmail.com
Sat Jun 19 01:07:34 CEST 2010

On Fri, Jun 18, 2010 at 2:15 PM, Horace Tso <Horace.Tso at pgn.com> wrote:
> You still couldn't sway me into the <- camp. '=' is better for yet two more reasons,
> 1. it requires one keystroke, rather than two,
> 2. to type '<', one has to hold Shift then the ',' key, so it's a total of three strokes all together.
> In a typical script, you have hundreds of assignment statements. Those extra keystroke translate into quite a bit more wear on your fingers.

I certainly appreciate the desire to save keystrokes particularly for
common tasks.  But I wonder, if '=' is the only assignment operator,
what is used for formal argument matching?

I find being able to distinguish the two makes code clearer (besides
that assignment within a function becomes more tedious), and, at least
for me, I have less assignment statements than argument matching.  It
also seems like a great deal of work to change such a fundamental
function for the relatively slight potential gain.

As a side note, for me it is less keystrokes because using a shortcut,
with two keystrokes, I can get ' <- ' which is the assignment plus
the space before and after it, which I would add for readability
anyways (although I suppose liking spaces in code may just be personal

> H
> -----Original Message-----
> From: Erik Iverson [mailto:eriki at ccbr.umn.edu]
> Sent: Friday, June 18, 2010 1:23 PM
> To: Greg Snow
> Cc: Horace Tso; li li; r-help
> Subject: Re: [R] questions on some operators in R
> Greg Snow wrote:
>> Your example could also be used as an argument against allowing '=' as a shortcut for <- after all if you are used to using <- (rather than =) then you will see the problem with x<-2 right off.  But if we eliminate <- and only use =, then how do you do:
>>> mean( x <- rnorm(100) )
>> Or
>>> system.time( output <- longrunningfunction(args) )
>> Is
>>> mean( { x=rnorm(100) } )
>> Really and improvement?
> Certainly not in my mind!
> For me, here is certainly an undefinable aesthetic appeal to the '<-'
> assignment operator.  The visual requirement of seeing '<-' for me is so
> strong, that even when running example code from this list, I must
> replace all assignments done with '=' to '<-' before submitting them to
> R! I've also noticed that there seems to be an association between using
> '=' for assignments and writing code with 0 spaces per line in it.  Of
> course, I insist on fixing that before running the code, too.  :)
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Joshua Wiley
Ph.D. Student
Health Psychology
University of California, Los Angeles

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