Tmap: non-standard projections do not work

[Nowosad]

See my comments:

library(tmap)
library(spData)

# st_transform does not support wintri ...---------------------------------
w2 = sf::st_transform(world, crs = "+proj=wintri")
#> Warning in CPL_crs_from_proj4string(x): GDAL cannot import PROJ.4 string
#> `+proj=wintri': returning missing CRS
#> OGR: Corrupt data
#> Error in CPL_transform(x, crs$proj4string): OGR error
# ... however, st_transform_proj does -------------------------------------
w3 = lwgeom::st_transform_proj(world, crs = "+proj=wintri")
#> Linking to GEOS 3.6.1, GDAL 2.2.4, proj.4 4.9.3
# it could be plot using sf::plot -----------------------------------------
plot(st_geometry(w3))

# but not using tmap ------------------------------------------------------
tm_shape(w3) + tm_polygons()
#> OGR: Corrupt data
#> Error in CPL_area(st_geometry(x)): OGR error

Created on 2018-07-10 by the reprex package (v0.2.0).

[mtennekes]

Thanks! I knew about the problems with the "wintri" projection, but didn't knew the lwgeom alternatives.

It should work now. I also made the helper functions from tmaptools more robust. See https://github.com/mtennekes/tmaptools/commit/0eb579af1c85b8b357a9e2e46193b6351cedaa80

[mtennekes]

Only the print "OGR: Corrupt data" cannot easily be suppressed.

[mtennekes]

Hmm, the lwgeom methods have problems with other projections, e.g. mercator:

all(sf::st_is_valid(world))
w4 = lwgeom::st_transform_proj(world, crs = "+proj=merc")
# Failed on geometry 7
# Error in CPL_lwgeom_transform(x, c(st_crs(x)$proj4string, crs)) : 
#  st_lwgeom_transform failed
w4 = sf::st_transform(world, crs = "+proj=merc")

[tim-salabim]

For more info see https://github.com/r-spatial/sf/issues/509

[mtennekes]

Ok, it should work now.

In tmaptools, I've created an internal function st_transform2 which first tries st_transform and than st_transform_proj.

Please reopen if needed.