[R-sig-Geo] st_write and gpx file

[Ahmadou Dicko]

I'm glad you found a solution, and indeed GPX need a track_fid and
track_seg_id for track points.
Regarding the driver issue, it's just because it was not added to the
list of extension automatically recognized by sf::st_write.
You can look at it here:
https://github.com/r-spatial/sf/blob/ddc79d0e9b7f7500a6d6020964b180cd4064bc83/R/read.R#L670-L695

You can raise an issue on the repository and make a case for it to be added.

Best,
Ahmadou


On Sun, Mar 6, 2022 at 6:44 AM Patrick Giraudoux <
patrick.giraudoux using univ-fcomte.fr> wrote:

> I have made some additionnal trials, with the argument 'driver'
> explicit. It appears that the sf object 'walk' must compulsory have two
> fields names "track_fid" and "track_seg_id" respectively. Once created :
>
> > walk  Simple feature collection with 2095 features and 3 fields Geometry
> type: POINT Dimension: XY Bounding box: xmin: 5.951268 ymin: 47.29238
> xmax: 5.974512 ymax: 47.3015 Geodetic CRS: WGS 84 First 10 features:
> track_fid ele geometry track_seg_id 1 1 243 POINT (5.95348 47.29709) 1 2
> 1 243 POINT (5.953438 47.29704) 1 3 1 244 POINT (5.953219 47.29702) 1 4
> 1 243 POINT (5.952884 47.29713) 1 5 1 243 POINT (5.952492 47.2972) 1 6 1
> 243 POINT (5.952335 47.29743) 1 7 1 242 POINT (5.951881 47.29732) 1 8 1
> 242 POINT (5.951495 47.29724) 1 9 1 293 POINT (5.951333 47.29719) 1 10 1
> 294 POINT (5.951388 47.29706) 1
>
>
> Then,
>
> st_write(walk,dsn="walk.gpx",layer="track_points",driver="GPX")
>
> is written with no error
>
> However, st_write(walk,dsn="walk.gpx",layer="track_points") still gets
> 'Error: Could not guess driver for walk.gpx'
>
>
>
>
> Le 05/03/2022 à 20:24, Ahmadou Dicko a écrit :
> > Hi Patrick,
> >
> > You can add the driver manually.
> >
> > st_write(walk, dsn = "walk.gpx", layer = "track_points", driver = "GPX")
> >
> > Hope it helps,
> > Ahmadou
> >
> >
> > On Sat, Mar 5, 2022 at 6:53 PM Patrick Giraudoux
> > <patrick.giraudoux using univ-fcomte.fr> wrote:
> >
> >     Dear listers,
> >
> >     I am making trials with the sf package trying to write point
> >     geometries
> >     into afile. Here is the sf object:
> >
> >     > walk  Simple feature collection with 2095 features and 2 fields
> >     Geometry
> >     type: POINT Dimension: XY Bounding box: xmin: 5.951268 ymin: 47.29238
> >     xmax: 5.974512 ymax: 47.3015 Geodetic CRS: WGS 84 First 10 features:
> >     track_seg_point_id ele geometry 1 0 243 POINT (5.95348 47.29709) 2
> >     1 243
> >     POINT (5.953438 47.29704) 3 2 244 POINT (5.953219 47.29702) 4 3 243
> >     POINT (5.952884 47.29713) 5 4 243 POINT (5.952492 47.2972) 6 5 243
> >     POINT
> >     (5.952335 47.29743) 7 6 242 POINT (5.951881 47.29732) 8 7 242 POINT
> >     (5.951495 47.29724) 9 8 293 POINT (5.951333 47.29719) 10 9 294 POINT
> >     (5.951388 47.29706)
> >
> >     Writing a shapefile as well as a kml is no problem:
> >
> >     st_write(walk,"walk.shp")
> >
> >     st_write(walk,"walk.kml")
> >
> >     But I cannot go through writing a gpx file, e.g.
> >
> >     > st_write(walk,dsn="walk.gpx",layer="track_points") Error: Could
> >     not guess driver for walk.gpx
> >
> >     I have tried several other combinations all unsuccessful.
> >
> >     Have someone an idea about what goes wrong ?
> >
> >     Best,
> >
> >     Patrick
> >
> >
> >
> >
> >
> >             [[alternative HTML version deleted]]
> >
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> >
> >
> >
> > --
> > Ahmadou H. DICKO, PhD
> >
> > Statistical consultant
> > Mobile: (+221) 77 123 81 69
> > Skype: dicko.ahmadou.h
> > Twitter : @dickoah
> > Gitlab: gitlab/dickoa
> > Github: github/dickoa
>
>
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-- 
Ahmadou H. DICKO, PhD

Statistical consultant
Mobile: (+221) 77 123 81 69
Skype: dicko.ahmadou.h
Twitter : @dickoah
Gitlab: gitlab/dickoa
Github: github/dickoa

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