[Rd] access an element with empty name
Kurt@Hornik @ending from wu@@c@@t
Mon May 14 15:55:47 CEST 2018
>>>>> Serguei Sokol writes:
> I came across a case where I cannot access a list element by its empty name.
> Minimal example can be constructed as
> x=list("A", 1)
> names(x)=c("a", "")
> # "A"
> # "A"
> # Error: attempt to use zero-length variable name
> # but we can still access the second element by its index
> # 1
> To my mind, it should be perfectly legal to access an element by an
> empty name as we can have for example
> match("", names(x))
> # 2
> Hence a traditional question: is it a bug or feature?
A feature according to the docs: ? Extract says
Neither empty (‘""’) nor ‘NA’ indices match any names, not even
empty nor missing names.
> R version 3.5.0 (2018-04-23)
> Platform: x86_64-pc-linux-gnu (64-bit)
> Running under: Mageia 6
> Matrix products: default
> BLAS/LAPACK: /home/opt/OpenBLAS/lib/libopenblas_sandybridge-r0.3.0.dev.so
>  C
> attached base packages:
>  stats graphics grDevices utils datasets methods base
> loaded via a namespace (and not attached):
>  compiler_3.5.0
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