[R] Does a formula object have a "left hand side"

[Erik Iverson]

Excellent, thank you all!

William Dunlap wrote:
> attr(terms(formula), "response") is 1 if
> the formula has a left hand side and 0
> otherwise.
> 
> At a lower level, you can look at
> length(formula): 2 means there is no LHS,
> 3 means there is (any other value indicates
> that someone made a call object that the
> parser would not make).
> 
> Bill Dunlap
> Spotfire, TIBCO Software
> wdunlap tibco.com  
> 
>> -----Original Message-----
>> From: r-help-bounces at r-project.org 
>> [mailto:r-help-bounces at r-project.org] On Behalf Of Erik Iverson
>> Sent: Monday, December 13, 2010 12:17 PM
>> To: R-help
>> Subject: [R] Does a formula object have a "left hand side"
>>
>> Hello,
>>
>> Does anyone know of a function that will determine whether
>> or not a formula object has a left hand side?
>>
>> I.e., can differentiate between
>>
>> y ~ x + z
>>
>> and
>>
>> ~ x + z
>>
>> Perhaps I'm overlooking the obvious...
>>
>> Thanks!
>>
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