Suppose I have:
Book Value
A 10
B 11
C 9
D 8
A 12
C 4
D 5
B 7
I want to summarize above not by Book but by groupings of Books as in
(below)
I have a list ... basic_map <- list(c("A",B"),c("C,D"))
Big_names <- c("A1", "A2")
Names(basic_map) <- big_names
Try this:
testdf <- data.frame(book=factor(c("A", "B", "C", "D", "A", "C", "D",
"B")), value=c(10,11,9,8,12,4,5,7))
bookgroup <- rep("A1", nrow(testdf))
bookgroup[testdf$book=="C" | testdf$book=="D"] <- "A2"
tapply(testdf$value, bookgroup, sum)
Regards,
Richie.
Mathematical Sciences Unit
HSL
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