no visible binding for global variable for data sets in a package

Wed, Aug 27, 2014 6:29 AM

On 8/27/2014 5:24 AM, Martin Maechler wrote:

Michael Friendly <friendly at yorku.ca>
     on Tue, 26 Aug 2014 17:58:34 -0400 writes:

     > I'm updating the Lahman package of baseball statistics to the 2013
     > release. In addition to
     > the main data sets, the package also contains several convenience
     > functions that make use
     > of these data sets.  These now trigger the notes below from R CMD check
     > run with
     > Win builder, R-devel.  How can I avoid these?

     > * using R Under development (unstable) (2014-08-25 r66471)
     > * using platform: x86_64-w64-mingw32 (64-bit)
     > ...
     > * checking R code for possible problems ... NOTE
     > Label: no visible binding for global variable 'battingLabels'
     > Label: no visible binding for global variable 'pitchingLabels'
     > Label: no visible binding for global variable 'fieldingLabels'
     > battingStats: no visible binding for global variable 'Batting'
     > battingStats: no visible global function definition for 'mutate'
     > playerInfo: no visible binding for global variable 'Master'
     > teamInfo: no visible binding for global variable 'Teams'

     > One such function:

     > ## function for accessing variable labels

     > Label <- function(var, labels=rbind(battingLabels, pitchingLabels,
     > fieldingLabels)) {
     > wanted <- which(labels[,1]==var)
     > if (length(wanted)) labels[wanted[1],2] else var
     > }

and you are using the data sets you mentioned before,
(and the checking has been changed recently here).

This is a bit subtle:
Your data sets are part of your package (thanks to the default
lazyData), but *not* part of the namespace of your package.
Now, the reasoning goes as following: if someone uses a function
from your package, say Label() above,
by
	Lahman::Label(..)
and your package has not been attached to the search path,
your user will get an error, as the datasets are not found by
Label().

If you consider something like   Lahman::Label(..)
for a bit and the emphasis we put on R functions being the
primary entities, you can understand the current, i.e. new,
R CMD check warnings.

Thanks for this explicit explanation.  Now I understand why this occurs.

Not sure I quite understand how this would work.  My NAMESPACE currently 
exports
the few functions in this package:

# all the rest is data
export(battingStats,
     playerInfo,teamInfo,
     Label
     )

Do you mean to simply add all the data sets ('globals')  that are 
referred to in these functions?

# all the rest is data
export(battingStats,
     playerInfo,teamInfo,
     Label,
     battingLabels, pitchingLabels, fieldingLabels,
     Batting, Master, Teams
     )

That seems a bit odd.  Can you actually export data?  Maybe there is a 
need for a
separate NAMESPACE declaration, that might be called either of

exportdata()
globaldata()

So, this would be version 1 of "2)":

Label <- function(var, labels) {
     stopifnot(require(Lahman, quietly=TRUE))
     if(missing(labels)) labels <- rbind(battingLabels, pitchingLabels, 
fieldingLabels)
     wanted <- which(labels[,1]==var)
     if (length(wanted)) labels[wanted[1],2] else var
}

And this would be version 2, using data():

Label <- function(var, labels) {
     stopifnot(require(Lahman, quietly=TRUE))
     if(missing(labels)) {
         data(battingLabels); data(pitchingLabels); data(fieldingLabels)
         labels <- rbind(battingLabels, pitchingLabels, fieldingLabels)
         }
     wanted <- which(labels[,1]==var)
     if (length(wanted)) labels[wanted[1],2] else var
}

Michael Friendly     Email: friendly AT yorku DOT ca
Professor, Psychology Dept. & Chair, Quantitative Methods
York University      Voice: 416 736-2100 x66249 Fax: 416 736-5814
4700 Keele Street    Web:http://www.datavis.ca
Toronto, ONT  M3J 1P3 CANADA

no visible binding for global variable for data sets in a package

Thread (14 messages)