[R] Partial matching with $ extractor.

[Andrew Simmons]

junk$y extracts the element named "y" because it found an exact match for
the name.

junk$yu extracts nothing because it does not find an exact match and finds
multiple partial matches.

junk$yuc or junk$yur would work because it finds no exact match and then
exactly one partial match.

On Tue, Jan 24, 2023, 17:04 Rolf Turner <r.turner using auckland.ac.nz> wrote:

>
> Has something changed, but I missed it?
>
> My recollection is that $ extraction used partial matching.
>
> E.g. if one did
>
>     junk <- list(yuck=1,yurk=2,y=3)
>     junk$y
>
> then one would get 1 as the result; probably *not* the desired result.
> See fortunes::fortune("toad").
>
> To get the desired result, one would need to use junk[["y"]].
>
> Likewise junk$yu would give 1; to get the value of "yurk", one would
> need to use junk$yur or junk$yurk or (better?) junk[["yurk"]].
>
> However, either my recollection is wrong, or something has changed.
> When I do junk$y I get 3 (the "right" answer; the same as junk[["y"]]).
> When I do junk$yu I get NULL (just as if I'd done junk[["yu"]]).
>
> So: has something changed, or am I miss-remembering, or am I completely
> confused about the whole issue?
>
> Thanks for any enlightenment.
>
> cheers,
>
> Rolf Turner
>
> --
> Honorary Research Fellow
> Department of Statistics
> University of Auckland
> Phone: +64-9-373-7599 ext. 88276
>
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