[R] subsetting by cell value with a list

[Petr Savicky]

On Thu, Mar 15, 2012 at 03:47:24PM -0500, G See wrote:
> On second thought, I must not understand your question because your
> code works fine for me.
> 
> > my.df[ which(my.df$IDX == c(17, 42)), ]
>    IDX          x
> 17  17 -0.5110095
> 42  42 -1.0686427

Hi.

This seems to work due to the fact that 17 is odd
and 42 is even, so they appear at the right place
in recycling c(17, 42).

  IDX <- 1:50
  which(IDX == c(17, 42))
  [1] 17 42
  
  which(IDX == c(18, 42))
  [1] 42
  
  which(IDX == c(18, 43))
  integer(0)

Petr Savicky.