[R] Is a list an atomic object? (or is there an issue with the help page of ?tapply ?)

Tal Galili tal.galili at gmail.com
Sat Feb 4 13:17:01 CET 2017


In the help page of ?tapply it says that the first argument (X) is "an
atomic object, typically a vector."

However, tapply seems to be able to handle list objects. For example:

###################

l <- as.list(1:10)
is.atomic(l) # FALSE
index <- c(rep(1,5),rep(2,5))
tapply(l,index,unlist)

> tapply(l,index,unlist)
$`1`
[1] 1 2 3 4 5

$`2`
[1]  6  7  8  9 10


###################

Hence, does it mean a list an atomic object? (which I thought it wasn't) or
is the help for tapply needs updating?
(or some third option I'm missing?)

Thanks.





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