OK, this is very elementary, but I need help.  I have looked in Verzani,
past postings etc.

Problem:  I need to subtract the "length" date between "h4" and "a3"  #which
would be 4-1
I would rather not convert the two columns into four columns (with headings
being "a3","a4","c4","h4").


DF <- data.frame(length=c(1,2,3,4),
Tanks=c("a3","a4","c4","h4"))

???

Much appreciated, keith

	[[alternative HTML version deleted]]

