[R] Making objects global in a package

[William Dunlap]

What the OP is doing looks fine to me.

The environment holding the data vectors is not necessary, but it helps
organize things - you know where to look for this sort of data vector.

I would avoid the *.rda file, since it is not text, hence not readily
editable
or trackable with most source control systems.


Bill Dunlap
TIBCO Software
wdunlap tibco.com

On Fri, Jul 13, 2018 at 6:17 PM, Jeff Newmiller <jdnewmil using dcn.davis.ca.us>
wrote:

> a) There is a mailing list for package development questions:
> R-package-devel.
>
> b) This seems like a job for the sysdata.rda file... no explicit
> environments needed. See the Writing R Extensions manual.
>
> On July 13, 2018 5:51:06 PM PDT, Michael Hannon <
> jmhannon.ucdavis using gmail.com> wrote:
> >Greetings.  I'm putting together a small package in which I use
> >`dplyr::read_csv()` to read CSV files from several different sources.
> >I do
> >this in several different files, but with various kinds of subsequent
> >processing, depending on the file.
> >
> >I find it useful to specify column types, as the apparent data type of
> >a given
> >column sometimes changes unexpectedly deep into the file.  I.e., a
> >field that
> >consistently looks like an integer, suddenly becomes a fraction:
> >
> >    1, 1, ..., 1, 1/2, 1, ...
> >
> >Hence, the column type has to be treated as a character, rather than as
> >an
> >integer (with the possibility of later conversion to double, if
> >necessary).
> >(This is just an example.)
> >
> >Therefore I use the `col_types` argument in all of the calls to
> >`read_csv()`.
> >
> >These calls are spread over several files, but I want the keep all of
> >the
> >column types in a single place, yet have them available in each of the
> >several
> >files.  This is just for the sake of maintainability.
> >
> >At the moment I do this by putting the column-type definitions into a
> >single,
> >file:
> >
> >    000_define_data_attributes.R
> >
> >that:
> >
> >    (1) is named so that it's parsed first by `devtools::build()`
> >    (2) sets up an environment and stuffs the column types into it:
> >
> >            data_env <- new.env(parent=emptyenv())
> >            data_env$col_types_alpha <- list(
> >                Date = col_date(),
> >                var1 = col_double(),
> >                ...
> >            )
> >
> >There are a few other things that go into the file as well.
> >
> >Then I pick off the appropriate stuff from the environment in the other
> >files:
> >
> >foo_alpha <- read_csv("alpha.csv", col_types =
> >data_env$col_types_alpha)
> >
> >This seems to work, but it doesn't "feel" right to me.  (If this were
> >Python,
> >people would accuse me of being "non-pythonic").
> >
> >Hence, I'm seeking suggestions for the best practice for this kind of
> >thing.
> >
> >BTW, I note that both the sources of data ("alpha", etc.) and the
> >column types
> >are more or less guaranteed to be static for the foreseeable future.
> >Hence,
> >there really isn't much danger in just replicating the column-type
> >definitions
> >in each of the various files, which would obviate the need for the
> >"000..."
> >file.  In other words, this is mostly a style thing.
> >
> >Thanks for any advice you can provide.
> >
> >-- Mike
> >
> >______________________________________________
> >R-help using 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.
>
> --
> Sent from my phone. Please excuse my brevity.
>
> ______________________________________________
> R-help using 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.
>

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