[R] difference between <- and =

[Spencer Graves]

Thank, Peter, for the clarification:  You are correct on both counts. 
For the moment, I'm stuck working in an organization with many users of 
"another R-like language", and I must use the same dialect as they do. 
Migration is on my long-term planning horizon but won't happen soon.

	  Thanks also for your many interesting and useful contributions to my 
education and that of many others.

Best Wishes,
Spencer Graves

Peter Dalgaard BSA wrote:
> Spencer Graves <spencer.graves at pdf.com> writes:
> 
> 
>>	  A common, punishing error for me, with DF being a data
>>frame, is the following:
>>
>>	  if(DF$a = 1) ...
>>
>>	  where I intended to write "if(DF$a == 1)...".  This error
>>first replaces column "a" of DF with the trivial vector 1 (of length
>>1), and then interprets that as a logical, which evaluates as TRUE.
>>Unless the "if" statement otherwise generates an error, I must restore
>>column "a" from somewhere before I can continue.
> 
> 
> Eh?
> 
> 
>>a <- list(x=2)
>>if (a$x = 1) 5
> 
> Error: syntax error
> 
> I think you're referring to another R-like language....
> 
>  
> 
>>	   In addition to specifying function arguments, I also use
>>"=" to specify named components of a list or a vector.  That works
>>fine for me. It's only the accidental use of "=" when I mean "==" that
>>creates problems.
> 
> 
> (Actually, that's the same thing. list() and c() are function calls like
> (almost) everything else.)
>