[R] the less-than-minus gotcha

[Jim Lemon]

"Moral of story, computers do what you tell them, not what you meant."

Not only a fortune, but profound wisdom.

Jim


On Mon, Feb 2, 2015 at 12:38 PM, Kevin E. Thorpe
<kevin.thorpe at utoronto.ca> wrote:
> Using = has it's problems too.
>
> For example,
>
> print(fit <- lm(...))
>
> Assigns the result of the lm call to fit and prints the results. This is
> quite a useful trick actually.
>
> print(fit = lm(...))
>
> Throws an error.
>
> Moral of story, computers do what you tell them, not what you meant.
>
> Kevin
>
> On 02/01/2015 08:26 PM, Steve Taylor wrote:
>>
>> All the more reason to use = instead of <-
>>
>>
>> -----Original Message-----
>> From: R-help [mailto:r-help-bounces at r-project.org] On Behalf Of Ben Bolker
>> Sent: Monday, 2 February 2015 2:07p
>> To: r-help at stat.math.ethz.ch
>> Subject: Re: [R] the less-than-minus gotcha
>>
>> Mike Miller <mbmiller+l <at> gmail.com> writes:
>>
>>>
>>> I've got to remember to use more spaces.  Here's the basic problem:
>>>
>>> These are the same:
>>>
>>> v< 1
>>> v<1
>>>
>>> But these are extremely different:
>>>
>>> v< -1
>>> v<-1
>>>
>>
>> This is indeed documented, in passing, in one of the pages you listed:
>>
>> http://tim-smith.us/arrgh/syntax.html
>>
>> Whitespace is meaningless, unless it isn't. Some parsing ambiguities
>> are resolved by considering whitespace around operators. See and
>> despair: x<-y (assignment) is parsed differently than x < -y (comparison)!
>>
>
>
> --
> Kevin E. Thorpe
> Head of Biostatistics,  Applied Health Research Centre (AHRC)
> Li Ka Shing Knowledge Institute of St. Michael's
> Assistant Professor, Dalla Lana School of Public Health
> University of Toronto
> email: kevin.thorpe at utoronto.ca  Tel: 416.864.5776  Fax: 416.864.3016
>
>
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