R help - Oct 2022 - Unexpected result for df column $ subset with non-existent name

Does this explain it: (from ?Extract)


name
A literal character string or a name (possibly backtick quoted). For
extraction, this is normally (see under ?Environments?) **partially
matched** to the names of the object.

-- Bert

On Fri, Oct 28, 2022 at 6:53 AM Sergei Ko <sggp.sergei at gmail.com>
wrote:
>
> Hi All,
>
> Just noticed that R returns results for non-existent name if you have
> another variable with the same beginning when you subset with $.
> See the code below:
> name_0 <- "ID"
> name_1 <- "name"
> name_2 <- "name1"
>
> v0 <- 1:200
> v1 <- c(rep(0,100), rep(1,100))
> v2 <- c(rep(0,50), rep(1,150))
>
> df <- as.data.frame(cbind(v0, v1, v2))
> colnames(df) <- c(name_0, name_1, name_2)
>
> df_1 <- df[, c(name_0, name_1)]
> df_2 <- df[, c(name_0, name_2)]
>
> table(df$name)
> table(df_1$name)
> table(df_2$name)
> colnames(df_2)[2] <- "name10"
> table(df_2$name)
> colnames(df_2)[2] <- "name_any"
> table(df_2$name)
> table(df_2[,"name"])
>
> The last row produces an error as intended.
> Any ideas?
>
> Win 10
> R version 4.2.1 (2022-06-23 ucrt) -- "Funny-Looking Kid"
>
> Regards,
> Sergiy
>
>         [[alternative HTML version deleted]]
>
> ______________________________________________
> R-help at 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.

For what it's worth, I set these options to warn me about partial matches:

options(warnPartialMatchArgs = TRUE,
        warnPartialMatchAttr = TRUE,
        warnPartialMatchDollar = TRUE)

That warns about this particular case, as well as partial argument
name matches in function calls. I don't remember what the partial
match attr does, but past me wanted to be warned about it for some
reason.

Best,
Josh

On Fri, Oct 28, 2022 at 9:26 AM Bert Gunter <bgunter.4567 at gmail.com>
wrote:
>
> Does this explain it: (from ?Extract)
>
>
> name
> A literal character string or a name (possibly backtick quoted). For
> extraction, this is normally (see under ?Environments?) **partially
> matched** to the names of the object.
>
> -- Bert
>
> On Fri, Oct 28, 2022 at 6:53 AM Sergei Ko <sggp.sergei at gmail.com>
wrote:
> >
> > Hi All,
> >
> > Just noticed that R returns results for non-existent name if you have
> > another variable with the same beginning when you subset with $.
> > See the code below:
> > name_0 <- "ID"
> > name_1 <- "name"
> > name_2 <- "name1"
> >
> > v0 <- 1:200
> > v1 <- c(rep(0,100), rep(1,100))
> > v2 <- c(rep(0,50), rep(1,150))
> >
> > df <- as.data.frame(cbind(v0, v1, v2))
> > colnames(df) <- c(name_0, name_1, name_2)
> >
> > df_1 <- df[, c(name_0, name_1)]
> > df_2 <- df[, c(name_0, name_2)]
> >
> > table(df$name)
> > table(df_1$name)
> > table(df_2$name)
> > colnames(df_2)[2] <- "name10"
> > table(df_2$name)
> > colnames(df_2)[2] <- "name_any"
> > table(df_2$name)
> > table(df_2[,"name"])
> >
> > The last row produces an error as intended.
> > Any ideas?
> >
> > Win 10
> > R version 4.2.1 (2022-06-23 ucrt) -- "Funny-Looking Kid"
> >
> > Regards,
> > Sergiy
> >
> >         [[alternative HTML version deleted]]
> >
> > ______________________________________________
> > R-help at 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.
>
> ______________________________________________
> R-help at 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.


-- 
Joshua Ulrich  |  about.me/joshuaulrich
FOSS Trading  |  www.fosstrading.com