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

The change would seem to be this

      \item \command{R CMD check} now by default checks code usage
      directly on the package namespace without loading and attaching
      the package and its suggests and enhances.

and perhaps the remedies could be stated more clearly?

Putting the data objects in the namespace would seem the obvious thing to
do.

One oddity is that they are sort of in there already:

Lahman::battingLabels

    variable                             label
1   playerID                    Player ID code
2     yearID                              Year
3      stint                    Player's stint
4     teamID                              Team
5       lgID                            League
6          G                             Games
7  G_batting                   Games as batter
8         AB                           At Bats
9          R                              Runs
10         H                              Hits
11       X2B                           Doubles
12       X3B                           Triples
13        HR                          Homeruns
14       RBI                    Runs Batted In
15        SB                      Stolen Bases
16        CS                   Caught Stealing
17        BB                     Base on Balls
18        SO                        Strikeouts
19       IBB                 Intentional walks
20       HBP                      Hit by pitch
21        SH                    Sacrifice hits
22        SF                   Sacrifice flies
23      GIDP        Grounded into double plays
24     G_Old Old version of games (deprecated)

But then again, actually not:

Lahman::Label()

Error in rbind(battingLabels, pitchingLabels, fieldingLabels) :
  object 'battingLabels' not found

This is documented (:: can access datasets made available by
lazy-loading), but it sort of suggests that we might want to improve
consistency in this area.

-pd


On 27 Aug 2014, at 11:24 , Martin Maechler <maechler at stat.math.ethz.ch>
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.

I see the following two options for you:

1) export all these data sets from your NAMESPACE
  For this (I thinK), you must define them in  Lahman/R/ possibly via a
  Lahman/R/sysdata.rda

2) rewrite your functions such that ensure the data sets are
  loaded when they are used.


"2)" actually works by adding
      stopifnot(require(Lahman, quietly=TRUE))
 as first line in Label() and other such functions.

It works in the sense that  Lahman::Label("yearID")  will
work even when Lahman is not in the search path,
but   R-devel CMD check   will still give the same NOTE,
though you can argue that that note is actally a "false positive".

Not sure about another elegant way to make "2)" work, apart from
using  data() on each of the datasets inside the
function.  As I haven't tried it, that may *still* give a
(false) NOTE..

This is a somewhat interesting problem, and I wonder if everyone
else has solved it with '1)' rather than a version of '2)'.

Martin

--
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