If I understand correctly, no looping (ave(), for()) or type casting
(as.character()) is needed -- indexing and matching suffice:
> with(df, ID[!ID %in% unique(ID[samples %in% c("B","C") ])])
[1] 3 3
Cheers,
Bert
Bert Gunter
"The trouble with having an open mind is that people keep coming along
and sticking things into it."
-- Opus (aka Berkeley Breathed in his "Bloom County" comic strip )
On Sat, Jul 15, 2017 at 8:54 AM, David Winsemius <[email protected]> wrote:
>
>> On Jul 15, 2017, at 4:01 AM, Andras Farkas via R-help <[email protected]>
>> wrote:
>>
>> Dear All,
>>
>> wonder if you could please assist with the following
>>
>> df<-data.frame(ID=c(1,1,1,2,2,3,3,4,4,5,5),samples=c("A","B","C","A","C","A","D","C","B","A","C"))
>>
>> from this data frame the goal is to extract the value of 3 from the ID
>> column based on the logic that the ID=3 in the data frame has NO row that
>> would pair 3 with either "B", AND/OR "C" in the samples column...
>>
>
> This returns a vector that determines if either of those characters are in
> the character values of that factor column you created. Coercing to character
> is needed because leaving samples as a factor generated an invalid factor
> level warning and gave useless results.
>
> with( df, ave( as.character(samples), ID, FUN=function(x) {!any(x %in%
> c("B","C"))}))
> [1] "FALSE" "FALSE" "FALSE" "FALSE" "FALSE" "TRUE" "TRUE" "FALSE" "FALSE"
> [10] "FALSE" "FALSE"
>
> You can then use it to extract and consolidate to a single value (although
> wrapping with as.logical was needed because `ave` returned character class
> values):
>
> unique( df$ID[ as.logical( # fails without this since "FALSE" != FALSE
> with( df,
> ave( as.character(samples), ID, FUN=function(x)
> {!any(x %in% c("B","C"))})))
> ] )
> #[1] 3
>
> The same sort of logic could also be constructed with a for-loop:
>
>> for (x in unique(df$ID) ) { if ( !any( df$samples[df$ID==x] %in% c("b","C"))
>> ) print(x) }
> [1] 3
>
> Although you are warned that for-loops do not return values and you might
> need to make an assignment rather than just printing.
>
> --
>
> David Winsemius
> Alameda, CA, USA
>
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