[R] use logical in cor.test

[Peter Ehlers]

On 2010-03-30 2:41, pgseye wrote:
>
> Thanks for the replies.
>
> In response to Erik:
> What does
>> Both[,1]
> show you?
>
>> Both[,1]
>     [1] 3.36   NA   NA   NA   NA   NA   NA 3.92 3.50   NA   NA   NA   NA 3.76
> 3.19 3.83   NA 3.66..........
>
> What does
>> Both[,1]>  2.5
> show you?
>
>> Both[,1]>2.5
>     [1]  TRUE    NA    NA    NA    NA    NA    NA  TRUE  TRUE    NA    NA
> NA    NA  TRUE  TRUE........
>
>
> I understand a logical variable is binary, but don't know how to select a
> subset of the data (have tried the subset function, but can't seem to get it
> to work)
>
> Bill, when I run what you suggested, I get:
>
>> tBoth<- Both
>> is.na(tBoth[tBoth>  2.5])<- TRUE
> Error in is.na(tBoth[tBoth>  2.5])<- TRUE :
>    NAs are not allowed in subscripted assignments
>> R<- cor(tBoth, use = "complete.obs")
>> R[1,2]
> [1] 0.7750889
>
> Any idea with the error message?

This happens because your 'Both' already has missing values.
You can replace the line

  is.na(tBoth[tBoth > 2.5]) <- TRUE

with

  tBoth[tBoth > 2.5] <- NA

and the rest should work.

>
> Thanks again,
>
> Paul

-- 
Peter Ehlers
University of Calgary