[R-sig-Geo] dissolve internal borders of polygons using st_union and group_by

[Michael Sumner]

rnaturalearth is really dirty data, there's no way forward when things are
so bad, only backing up can help.

Do you need the whole world? Where do you need, and what scale? Your
question suggests that finding the right data is the solution rather than
battling with software.

Cheers, Mike



On Fri., 18 Oct. 2019, 00:27 Roger Bivand, <Roger.Bivand using nhh.no> wrote:

> On Thu, 17 Oct 2019, Marta Rufino wrote:
>
> > Dear Roger,
> >
> > Thank you very much for your quick and dedicated response.
> >
> > Please state all versions:
> >> sessionInfo()
> >> sf_extSoftVersion()
> >
> > See bellow. I though it was a trivial issue, thus sorry for not reporting
> > it earlier.
> >
> >
> >> With an updated system, most of your code just does not work for me.
> >
> > Just updated everything, r included, and it still runs in my machine -
> > perhaps because I failed to update to proj6 and I am still using proj4 -
> I
> > will have to dedicate more time to overcome it. Is there sites that
> explain
> > win-dummies installation?
>
> You don't need to update yet, but modern PROJ will upset many workflows.
>
> >
> >
> >> You
> >> are looking for sf::aggregate():
> >> kk <- aggregate(world_map, list(world_map$continent), head, n=1)
> >> plot(st_geometry(kk))
> >>
> >
> > This will be then a fourth option:
> > # Answer from ROGER:
> > kk4 <- aggregate(world_map, list(world_map$continent), head, n=1)
> >
> > object.size(kk4)
> > kk4 %>%
> >  ggplot()+
> >  geom_sf()
> >
> > The sp_transform was simply to check if it was workable the produced file
> > (in other cases, the code functioned, but then I could not work with the
> > files produced) - so ok to remove it or change it.
> >
> > You example using rgeos is really nice and I am grateful for it, but I
> > really wanted to understand how to do it overall so I can apply in other
> > situations I am working with.
> > I don't understand the difference between all those options, that
> > apparently are giving the same result, but not so much in fact.
>
> My attempts to use st_precision() to try to find a precision level
> that removed the artefacts ended in segmentation faults, so the current
> best workaround is as shown to use rgeos, until the correct sf incantation
> is forthcoming.
>
> Roger
>
> >
> > Any further ideas on the subject?
> >
> > Thank you once again,
> > Best wishes,
> > M.
> >
> >
> >> sessionInfo()
> > R version 3.6.1 (2019-07-05)
> > Platform: x86_64-w64-mingw32/x64 (64-bit)
> > Running under: Windows >= 8 x64 (build 9200)
> >
> > Matrix products: default
> >
> > locale:
> > [1] LC_COLLATE=English_United Kingdom.1252
> > [2] LC_CTYPE=English_United Kingdom.1252
> > [3] LC_MONETARY=English_United Kingdom.1252
> > [4] LC_NUMERIC=C
> > [5] LC_TIME=English_United Kingdom.1252
> >
> > attached base packages:
> > [1] stats     graphics  grDevices utils     datasets  methods
> > [7] base
> >
> > other attached packages:
> > [1] rgeos_0.5-2         ggthemes_4.2.0      ggrepel_0.8.1
> > [4] ggplot2_3.2.1       tidyr_1.0.0         scales_1.0.0
> > [7] dplyr_0.8.3         reshape2_1.4.3      viridis_0.5.1
> > [10] viridisLite_0.3.0   units_0.6-5         rnaturalearth_0.1.0
> > [13] tmap_2.3-1          mapview_2.7.0       plotKML_0.5-9
> > [16] lubridate_1.7.4     zoo_1.8-6           rasterVis_0.46
> > [19] latticeExtra_0.6-28 RColorBrewer_1.1-2  lattice_0.20-38
> > [22] raster_3.0-7        maptools_0.9-8      sf_0.8-0
> > [25] gstat_2.0-3         rgdal_1.4-6         sp_1.3-1
> >
> > loaded via a namespace (and not attached):
> > [1] colorspace_1.4-1   class_7.3-15       colorRamps_2.3
> > [4] leaflet_2.0.2      htmlTable_1.13.2   satellite_1.0.1
> > [7] base64enc_0.1-3    dichromat_2.0-0    rstudioapi_0.10
> > [10] hexbin_1.27.3      fansi_0.4.0        codetools_0.2-16
> > [13] splines_3.6.1      knitr_1.25         zeallot_0.1.0
> > [16] Formula_1.2-3      tmaptools_2.0-2    cluster_2.1.0
> > [19] png_0.1-7          shiny_1.4.0        compiler_3.6.1
> > [22] backports_1.1.5    assertthat_0.2.1   Matrix_1.2-17
> > [25] fastmap_1.0.1      lazyeval_0.2.2     cli_1.1.0
> > [28] later_1.0.0        acepack_1.4.1      htmltools_0.4.0
> > [31] tools_3.6.1        gtable_0.3.0       glue_1.3.1
> > [34] Rcpp_1.0.2         vctrs_0.2.0        leafsync_0.1.0
> > [37] crosstalk_1.0.0    lwgeom_0.1-7       xfun_0.10
> > [40] stringr_1.4.0      mime_0.7           lifecycle_0.1.0
> > [43] XML_3.98-1.20      MASS_7.3-51.4      promises_1.1.0
> > [46] parallel_3.6.1     yaml_2.2.0         gridExtra_2.3
> > [49] aqp_1.17           rpart_4.1-15       reshape_0.8.8
> > [52] stringi_1.4.3      plotrix_3.7-6      e1071_1.7-2
> > [55] checkmate_1.9.4    intervals_0.15.1   rlang_0.4.0
> > [58] pkgconfig_2.0.3    pixmap_0.4-11      RSAGA_1.3.0
> > [61] purrr_0.3.2        htmlwidgets_1.5.1  tidyselect_0.2.5
> > [64] plyr_1.8.4         magrittr_1.5       R6_2.4.0
> > [67] Hmisc_4.2-0        DBI_1.0.0          pillar_1.4.2
> > [70] foreign_0.8-72     withr_2.1.2        shapefiles_0.7
> > [73] xts_0.11-2         survival_2.44-1.1  nnet_7.3-12
> > [76] tibble_2.1.3       spacetime_1.2-2    crayon_1.3.4
> > [79] utf8_1.1.4         KernSmooth_2.23-15 grid_3.6.1
> > [82] data.table_1.12.4  FNN_1.1.3          dismo_1.1-4
> > [85] digest_0.6.21      classInt_0.4-1     webshot_0.5.1
> > [88] xtable_1.8-4       httpuv_1.5.2       stats4_3.6.1
> > [91] munsell_0.5.0
> >> sf_extSoftVersion()
> >          GEOS           GDAL         proj.4 GDAL_with_GEOS
> >       "3.6.1"        "2.2.3"        "4.9.3"         "true"
> >    USE_PROJ_H
> >       "false"
> >>
> >
> >>
> >>
> >
>
> --
> Roger Bivand
> Department of Economics, Norwegian School of Economics,
> Helleveien 30, N-5045 Bergen, Norway.
> voice: +47 55 95 93 55; e-mail: Roger.Bivand using nhh.no
> https://orcid.org/0000-0003-2392-6140
> https://scholar.google.no/citations?user=AWeghB0AAAAJ&hl=en
>
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