These are deviations from the convention: ‘is.vector(as.vector(x, m), m)’
should be true for any mode ‘m’, including the default ‘"any"’.
* Case 1
These are documented.
- ‘is.vector’ returns ‘TRUE’ if ‘x’ is a vector of the specified mode having no
attributes _other than names_. It returns ‘FALSE’ otherwise.
- ‘as.vector’ removes _all_ attributes including names for results of atomic
mode (but not those of mode ‘"list"’ nor ‘"expression"’).
Because of the quirk of 'as.vector' for result of mode "list",
is.vector(as.vector(data.frame(a=1))) returns FALSE.
> is.vector(as.vector(data.frame(a=1)))
[1] FALSE
> is.vector(as.vector(data.frame(a=1), "list"), "list")
[1] FALSE
* Case 2
as.vector(call("c")) (mode="any", the default) is not an error.
On the other hand, as documented, if ‘mode = "any"’, ‘is.vector’ may return
‘TRUE’ for the atomic modes, ‘list’ and ‘expression’.
As a result, is.vector(as.vector(call("c"))) returns FALSE.
> is.vector(as.vector(call("c")))
[1] FALSE
> sessionInfo()
R version 3.0.1 (2013-05-16)
Platform: i386-w64-mingw32/i386 (32-bit)
locale:
[1] LC_COLLATE=English_United States.1252
[2] LC_CTYPE=English_United States.1252
[3] LC_MONETARY=English_United States.1252
[4] LC_NUMERIC=C
[5] LC_TIME=English_United States.1252
attached base packages:
[1] stats graphics grDevices utils datasets methods base
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