Hello,
Try the following.
d <- read.table(text="
D Y C
a 2005 10
a 2006 0
a 2007 9
b 2005 1
b 2006 0
b 2007 1
c 2005 5
c 2006 NA
c 2007 4 ", header=TRUE)
d
prn <- lapply(split(d, d$D), function(x){
x <- x[!is.na(x$C), ]
x[c(FALSE, diff(x$C)/x$C[-length(x$C)] < -0.5 & diff(x$C) < -5), ]
})
do.call(rbind, prn)
Hope this helps,
Rui Barradas
Em 23-07-2012 11:08, Katrin Ronnenberg escreveu:
hello there,
I'm an R beginner and got plunged into this. I guess my attempts are hopeless
so far, so I won't even show them.
I want to write a loop, which prints all erroneous values. My definition of
erroneous: If the current counts (partridge counts in a hunting district)
differ from last years counts by more than 50 percent and absolut values differ
by more than 5 animals I want r to print these values.
I have a grouping variable District "D", the year "Y" and the counts "C".
example table:
D Y C
a 2005 10
a 2006 0
a 2007 9
b 2005 1
b 2006 0
b 2007 1
c 2005 5
c 2006 NA
c 2007 4
Although the difference in a and b is 100 percent I would doubt a's population
breakdown, whereas District b is credible. To confuse things I want the loop to
skip missing values and instead look at the year after.
Any help is very much appreciated!
Thanks,
Katrin
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and provide commented, minimal, self-contained, reproducible code.
