Potential improvements of ave? (Act 2)

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Potential improvements of ave? (Act 2)

SOEIRO Thomas
Dear list,
 
This is a follow-up with another potential improvements of ave.
 
In the doc, x is documented as to be "a numeric", but this is not mandatory.
 
DF <- data.frame(x = letters, group = rep(1:2, each = 13))
ave(DF$x, DF$group, FUN = function(i) "a")
#  [1] "a" "a" "a" "a" "a" "a" "a" "a" "a" "a" "a" "a" "a" "a" "a" "a" "a" "a" "a"
# [20] "a" "a" "a" "a" "a" "a" "a"
 
However coercion can raise issues if the type of x and FUN(x) do not match. Coercion happens in split<-.default in the for loop with x[i] <- value[[j]].
(NB: In the following example, we can work around the problem by wrapping x with as.numeric.)
 
DF <- data.frame(x = Sys.Date() + 1:10, group = rep(1:2, each = 5))
ave(DF$x, DF$group, FUN = function(i) 1)
# Error in as.Date.numeric(value) : 'origin' must be supplied
 
So I have 2 questions/suggestions:
- Could the doc rather state that x must match the type of FUN(x) and warn for coercion?
- Could ave be more flexible (i.e. allow different type of x and FUN(x)) if using another approach than x[i] <- value[[j]] in split<-.default for recycling?
 
This has already been discussed on r-help and stackoverflow (e.g. https://stat.ethz.ch/pipermail/r-help/2016-November/442855.html)
 
Best,
 
Thomas

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