[R] intermittent errors in [.data.frame

[Duncan Murdoch]

On 03/07/2014 2:55 PM, Spencer Graves wrote:
>         I get inconsistent results from "[.data.frame".  I've so far been
> unable to create a simple, replicable example nor a workaround.  With
> debug, I traced the problem to "rows <- rows[i]", line 131 in
> "[.data.frame":  In this example, rows = 1:45, and rows[1:3] = 1:3, as
> we expect.  However with i = 1:3, rows[i] = c(1, 2, 2):
>
>
> Browse[4]> rows[1:3]
> [1] 1 2 3
> Browse[4]>i
> [1] 1 2 3
> Browse[4]>rows[i]
> [1] 1 2 2
>
>
>
>         Absent better suggestions, I currently plan to try to simplify my
> example as much as I can while retaining the error. Unfortunately, the
> search path includes 19 packages (see below), so I expect this not to be
> easy.  Other suggestions would be welcomed.

Are you computing i using floating point values?  You may have 2.9999999 
instead of 3; as an index, it is equivalent to 2, though it will print as 3.

Duncan Murdoch