[R] Identifying the particular X or Y in a sorted list

[Rui Barradas]

Hello,


Shankar Lanke wrote
> 
> Dear All,
> 
> I have a data sets as shown below A (Patient ID ), B and C are the
> Concentration of drug in blood on day 1 and day 4, D is the difference in
> conc. To do this in R I have written a code as follows, identified the
> number of patients who have more concentration on day 4 . Here I want to
> identify specifically the patient ID (is he patient 1 or 2 or 5 and 7),
> whose concentration is more.
> How to write a code to get the list of A (patient ID whose difference is
> more on day 4).
> 
> Data<-(myDf$B-myDf$C)
> sum(Data>0)
> 
>   A B CD (B-C)  1 14 10 4  2 12 7 5  3 11 15 -4  4 8 3 5  5 1 8 -7
> 
> I appreciate your help, thank you very much in advance.
> 
> Regards
> 
> 	[[alternative HTML version deleted]]
> 
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> 

If I understand it correctly, this should do it.

x <- read.table(text="
A B C D
1 14 10 4
2 12 7 5
3 11 15 -4
4 8 3 5
5 1 8 -7
", header=TRUE)

which(x$D == max(x$D))
x$A[ which(x$D == max(x$D)) ]

Or you can save the values of the which() function and use them when needed.

Hope this helps,
Rui Barradas



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