access an element with empty name
Serguei Sokol writes:
Hi, 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", "")
??? x[["a"]]
??? #[1]? "A"
??? x[[""]]
??? #NULL
??? x$`a`
??? #[1]? "A"
??? x$``
??? # Error: attempt to use zero-length variable name
??? # but we can still access the second element by its index
??? x[[2]]
??? #[1] 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))
??? #[1] 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.
-k
Best, Serguei.
sessionInfo()
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
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