[R] Working With Variables Having Different Lengths

[David Winsemius]

On Oct 21, 2011, at 4:38 PM, Rich Shepard wrote:

> On Fri, 21 Oct 2011, David Winsemius wrote:
>
>> How are we to determine which lines contain information about the
>> "relationships" of param=="TDS" with whatever cases or variable has  
>> values
>> of "Cond" and "SO4"? Are you really trying to compare two disjoint  
>> groups
>> on some statistic like the means and std-dev of "quant"? (This  
>> would be a
>> job for `aggregate`.)
>
>  When I try to select rows based on non-null contents for two values  
> of
> 'param' I don't have the correct syntax.

What problem are you trying to solve?

> Perhaps I need to use multiple data
> frames instead of a single one?

That seems very unlikely. What we need is a clearer description of  
that values that your "param" variable can assume, and what you want  
to within categories of those values. We also need you to stop  
dropping context.


>
> Rich
>
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David Winsemius, MD
West Hartford, CT