$ does not evaluate its second argument, it does something like as.character(substitute(name)).
You should be using lapply(list, function(x) x$a) or lapply(list, `[[`, "a") On Thu, Oct 27, 2022, 12:29 Hilmar Berger <hilmar.ber...@gmx.de> wrote: > Dear all, > > I'm a little bit surprised by the behavior of the $ operator when used > in lapply - any indication what might be wrong is appreciated. > > > xx = list(A=list(a=1:3, b=LETTERS[1:3]),"B"=list(a=7:9, > b=LETTERS[7:9])) > lapply(xx,`$`,"a") $A NULL $B NULL > `$`(xx[[1]],"a") > [1] 1 2 3 > > lapply(xx,`[`,"a") $A $A$a [1] 1 2 3 $B $B$a [1] 7 8 9 Any idea why I > `$`(object, name) works when applied to the single list element but not > within lapply (in contrast to `[`)? > I checked the help page of the extraction operators but could not find > anything that explains this. Thanks and best regards Hilmar > > sessionInfo() R version 4.2.1 (2022-06-23) Platform: x86_64-pc-linux-gnu > (64-bit) Running under: Ubuntu 20.04.5 LTS Matrix products: default > BLAS: /usr/lib/x86_64-linux-gnu/openblas-pthread/libblas.so.3 LAPACK: > /usr/lib/x86_64-linux-gnu/openblas-pthread/liblapack.so.3 locale: [1] > LC_CTYPE=en_US.UTF-8 LC_NUMERIC=C [3] LC_TIME=de_DE.UTF-8 > LC_COLLATE=en_US.UTF-8 [5] LC_MONETARY=de_DE.UTF-8 > LC_MESSAGES=en_US.UTF-8 [7] LC_PAPER=de_DE.UTF-8 LC_NAME=C [9] > LC_ADDRESS=C LC_TELEPHONE=C [11] LC_MEASUREMENT=de_DE.UTF-8 > LC_IDENTIFICATION=C attached base packages: [1] stats graphics grDevices > utils datasets methods base loaded via a namespace (and not attached): > [1] compiler_4.2.1 > > [[alternative HTML version deleted]] > > ______________________________________________ > R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide > http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. > [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
