enum: Enumerate items in an object.
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Description Usage Arguments Note See Also Examples

View source: R/misc.R

enum() is creating a vector of integers to enumarate items in an object. It is particularly useful in the for(i in enum(object)) construct.

enum(x)

`x`	Any object.

The pattern for(i in 1:length(object)) is often found, but it fails in case length(object) == 0! enum() is indeed a synonym of seq_along(), but the later one is less expressive in the context.

seq_along()

enum(letters)
enum(numeric(0))
# Compare with:
1:length(numeric(0))
enum(NULL)
letters5 <- letters[1:5]
for (i in enum(letters5)) cat("letter", i, "=", letters5[i], "\n")