[Rd] Deprecating partial matching in $.data.frame

[William Dunlap]

Will you be doing the same for attribute names?

  > options(prompt=with(version, paste0(language,"-",major,".",minor,"> ")))
  R-2.15.3> x <- structure(17, AnAttr="an attribute", Abcd="a b c d")
  R-2.15.3> attr(x, "A")
  NULL
  R-2.15.3> attr(x, "An")
  [1] "an attribute"
  R-2.15.3> attr(x, "Ab")
  [1] "a b c d"

How will you deal with the common idiom of using is.null(x$n)
to see if x has a compnent named "n"?  One would not want
a warning if x had a component called "nn".

Bill Dunlap
Spotfire, TIBCO Software
wdunlap tibco.com


> -----Original Message-----
> From: r-devel-bounces at r-project.org [mailto:r-devel-bounces at r-project.org] On Behalf
> Of peter dalgaard
> Sent: Wednesday, March 20, 2013 5:28 AM
> To: r-devel at r-project.org
> Subject: [Rd] Deprecating partial matching in $.data.frame
> 
> Allowing partial matching on $-extraction has always been a source of accidents.
> Recently, someone who shall remain nameless tried names(mydata) <- "d^2" followed by
> mydata$d^2.
> 
> As variables in a data frame are generally considered similar to variables in, say, the
> global environment, it seems strange that foo$bar can give you the content of
> foo$bartender.
> 
> In R-devel (i.e., *not* R-3.0.0 beta, but 3.1.0-to-be) partial matches now gives a warning.
> 
> Of course, it is inevitable that lazy programmers will have been using code like
> 
> > anova(fit1)$P
> [1] 0.0008866369           NA
> Warning message:
> In `$.data.frame`(anova(fit1), P) : Name partially matched in data frame
> 
> and now get the warning during package checks. This can always be removed by spelling
> out the column name, as in
> 
> > anova(fit1)$`Pr(>F)`
> [1] 0.0008866369           NA
> 
> or by explicitly specifying a partial match with
> 
> > anova(fit1)[["P", exact=FALSE]]
> [1] 0.0008866369           NA
> 
> 
> --
> Peter Dalgaard, Professor
> Center for Statistics, Copenhagen Business School
> Solbjerg Plads 3, 2000 Frederiksberg, Denmark
> Phone: (+45)38153501
> Email: pd.mes at cbs.dk  Priv: PDalgd at gmail.com
> 
> ______________________________________________
> R-devel at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-devel