Displaying 1 result from an estimated 1 matches for "tide_diff".
2011 Oct 26
1
Calculate the difference using ave
...", "A3"), each=3),
water = sample(c(100:200), 9),
tide = sample(c(-10:+10), 9))
df1
# What I want to calculate is:
# tide_[A2] / water_[A1],
# tide_[A3] / water_[A2]
# This 'works' for the example, but I am
# looking for a more general solution.
df1$tide_diff <- ave(df1$tide, FUN=function(L) L /
c(NA, NA, NA, df1$water)) * 100
df1
Thanks for any help!
Patrick