[R-pkg-devel] Problem with package containing spatial data

[Alexandre Courtiol]

Hi Igor,

I had the same issue using terra rather than sf a couple of weeks ago.

I thought of solving the issue as follow:


   1.

   store the shapefiles under extdata.
   2.

   create a function that loads the files:

.build_internal_files <- function() {
  ## This function should not be called by the user.
  ## It performs the lazy loading of the data since terra cannot
handle rda files
  assign("CountryBorders",
terra::vect(system.file("extdata/CountryBorders.shp", package =
"IsoriX")), envir = as.environment("package:IsoriX"))
  assign("OceanMask", terra::vect(system.file("extdata/OceanMask.shp",
package = "IsoriX")), envir = as.environment("package:IsoriX"))
}


   1. call that function automatically upon attach using .onAttach():

.onAttach <- function(libname, pkgname) {
    .build_internal_files() ## lazy loading of the internal data
}

It seems to work...

Note that .onAttach() is a standard way of defining a function that is
recognised by R and ran when the package is attached.

++

Alex

On Thu, 9 Feb 2023 at 11:11, Duncan Murdoch <murdoch.duncan using gmail.com>
wrote:

> On 09/02/2023 3:56 a.m., Ivan Krylov wrote:
> > В Wed, 8 Feb 2023 11:32:36 -0300
> > Igor L <igorlaltuf using gmail.com> пишет:
> >
> >> spatial_aisp <- sf::st_read('data-raw/shp_aisp/lm_aisp_2019.shp')
> >>
> >> plot(spatial_aisp) # works
> >>
> >> # Same data from .rda file after use usethis::use_data(spatial_aisp,
> >> overwrite = TRUE)
> >>
> >> x <- ispdata::spatial_aisp
> >>
> >> plot(x) # do not work
> >
> > Does this break in a new R session, but start working when you load the
> > sf namespace? I think that your package needs to depend on sf in order
> > for this to work. Specifying it in Imports may be enough to make the
> > plot.sf S3 method available to the user.
>
> Specifying a package in the Imports field of DESCRIPTION guarantees that
> it will be available to load, but doesn't load it.  Importing something
> from it via the NAMESPACE triggers a load, as does executing code like
> pkg::fn, or explicitly calling loadNamespace("pkg"), or loading a
> package that does one of these things.
>
>
> > You may encounter other problems if you go this way, like R CMD check
> > complaining that you don't use the package you're importing. Loading
> > the data from a file on demand would also load the sf namespace and
> > thus solve the problem.
>
> Workarounds for the check complaints are discussed here, among other
> places:  https://stackoverflow.com/a/75384338/2554330 .
>
> Duncan Murdoch
>
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>


-- 
Alexandre Courtiol, www.datazoogang.de

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