[R] all.equal() and which()

[Frank Samuelson]

I think that this thread demonstrates a useful point:
The more logical and useful output of all.equal(A,B) would be
a vector of TRUEs and FALSEs with a length equal to that of the arguments,
rather than some human readable text string.
If I really want a tolerance I can always do sd/min/max/etc(abs(A-B))
and have it in a useful numeric form.

-Frank


Marc Schwartz (via MN) wrote:
> On Fri, 2006-02-03 at 10:41 -0500, tom wright wrote:
> 
>>Please excuse the lack of a complete dataset here, if its needed I'll be
>>happy to provide it.
>>Can anyone show me how to rewrite this?
>>
>>Browse[1]> time(data)[24210:24220]
>>[1] 24.209 24.210 24.211 24.212 24.213 24.214 24.215 24.216 24.217 
>>[10] 24.218 24.219
>>
>>Browse[1]> which(time(data)==24.211)
>>numeric(0)
>>
>>I'm assuming its an eps fault but
>>which(all.equal(time(data),24.211))
>>
>>dosnt seem to work
> 
> 
> 
> There might be an easier way, but here is one approach:
> 
> 
>>mydat
> 
>  [1] 24.209 24.210 24.211 24.212 24.213 24.214 24.215 24.216 24.217
> [10] 24.218 24.219
> 
> 
>>which(sapply(mydat, function(x) isTRUE(all.equal(24.211, x))))
> 
> [1] 3
> 
> 
> This uses sapply() to check each element of 'mydat' against the target
> value of 24.211.  The use of 'isTRUE(all.equal(...))' returns a boolean
> result of either TRUE or FALSE, enabling the use of which() against the
> vector returned from sapply():
> 
> 
>>sapply(mydat, function(x) isTRUE(all.equal(24.211, x)))
> 
>  [1] FALSE FALSE  TRUE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE
> 
> See ?all.equal and ?isTRUE for more information.
> 
> HTH,
> 
> Marc Schwartz
> 
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