Recycling when one vector's length does not evenly divide into the other's is usually unintended. Most code throws a warning or an error:
> 1:3 + 1:2
 2 4 4
In 1:3 + 1:2 :
longer object length is not a multiple of shorter object length
> data.frame(a = 1:3, b = 1:2)
Error in data.frame(a = 1:3, b = 1:2) :
arguments imply differing number of rows: 3, 2
The pmin() and pmax() functions recycle silently in such cases:
> pmin(1:3, 1:2)
 1 2 1
It would be nice to get a warning here.
This is not a bug. Wishes should be marked as such (see the R FAQ).
fulfilled for 2.14.0