[EMAIL PROTECTED] said the following on 5/14/2008
12:40 PM:
Using R 2.6.2, say I have the following list of lists, "comb":
data1 <- list(a = 1, b = 2, c = 3)
data2 <- list(a = 4, b = 5, c = 6)
data3 <- list(a = 3, b = 6, c = 9)
comb <- list(data1 = data1, data2 = data2, data3 = data3)
So that all names for the lowest level list are common. How can I most
efficiently access all of the sublist items "a" indexed by the outer
list names? For example, I can loop through comb[[i]], unlisting as I
go, and then look up the field "a", as below, but there has got to be a
cleaner way.
finaldata <- double(0)
for(i in 1:length(names(comb))) {
test <- unlist(comb[[i]])
finaldata <- c(finaldata, test[which(names(test) == "a")])
}
data.frame(names(comb), finaldata)
Gives what I want:
names.comb. finaldata
1 data1 1
2 data2 4
3 data3 3
Any help you can give would be greatly appreciated. Thanks.
Try
data.frame(names.comb = names(comb),
finaldata = sapply(comb, "[[", "a"))
HTH,
--sundar
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