R Shapefile not plotting lat/lon correctly

Question

I'm having trouble plotting a shapefile correctly, it seems to have the geometry and projection recognised and I can see appropriate values in geometry$num (lat ~-34, lon ~153) but when plotted it is completely wrong. I assume the projection is wrong somewhere.

Shapefile can be accessed here: https://github.com/HaydenSchilling/Example_code_and_data/tree/master/shapefile

current code to reproduce issue is:

library(sf)
library(tidyverse)

dat <- sf::read_sf("227151 (1)99%fulltrack_WGS84.shp")

ggplot(dat) + geom_sf()

The result plot currently looks like:

How do I manually fix the projection?

Answer 1

(lat ~-34, lon ~153)

It looks like latitude & longitude have been swapped, and instead of transforming to projected CRS, CRS was just replaced.

Let's try to fix this:

library(sf)
#> Linking to GEOS 3.9.3, GDAL 3.5.2, PROJ 8.2.1; sf_use_s2() is TRUE
library(ggplot2)

shp_url <- "https://github.com/HaydenSchilling/Example_code_and_data/raw/master/shapefile/227151%20(1)99%25fulltrack_WGS84.shp"
dat <- sf::read_sf(paste0("/vsicurl/", shp_url))

# let's check the object, coordinates and proj4str
# X - easting, longitude
# Y - northing, latitude

dat 
#> Simple feature collection with 1 feature and 2 fields
#> Geometry type: POLYGON
#> Dimension:     XY
#> Bounding box:  xmin: -36.21875 ymin: 150.2143 xmax: -32.31378 ymax: 152.6772
#> Projected CRS: GDA94 / Geoscience Australia Lambert
#> # A tibble: 1 × 3
#>   timestamp             sn                                              geometry
#>   <chr>                 <chr>                                      <POLYGON [m]>
#> 1 2022-03-25-2022-06-18 227151 (1) ((-34.00546 150.2143, -34.01342 150.2143, -3…
st_coordinates(dat)[1:5,]
#>              X        Y L1 L2
#> [1,] -34.00546 150.2143  1  1
#> [2,] -34.01342 150.2143  1  1
#> [3,] -34.04276 150.2143  1  1
#> [4,] -34.04364 150.2143  1  1
#> [5,] -34.06255 150.2143  1  1
dat_crs <- st_crs(dat)
dat_crs$proj4string
#> [1] "+proj=lcc +lat_0=0 +lon_0=134 +lat_1=-18 +lat_2=-36 +x_0=0 +y_0=0 +ellps=GRS80 +units=m +no_defs"

# does not look like projected easting/northing ...
# let's make an assumption based on a file name and set (NOT transform) it to WGS84 :
dat_wgs84 <- st_set_crs(dat, "WGS84")
#> Warning: st_crs<- : replacing crs does not reproject data; use st_transform for
#> that

# swap lat/lon in geometry, g[,c(1,2)] <- g[,c(2,1)] :
dat_wgs84$geometry[[1]][[1]][,c(1,2)] <- dat_wgs84$geometry[[1]][[1]][,c(2,1)]

# and update bbox :
attr(st_geometry(dat_wgs84), "bbox") <- sfheaders::sf_bbox(dat_wgs84)

# check the result
dat_wgs84
#> Simple feature collection with 1 feature and 2 fields
#> Geometry type: POLYGON
#> Dimension:     XY
#> Bounding box:  xmin: 150.2143 ymin: -36.21875 xmax: 152.6772 ymax: -32.31378
#> Geodetic CRS:  WGS 84
#> # A tibble: 1 × 3
#>   timestamp             sn                                              geometry
#> * <chr>                 <chr>                                      <POLYGON [°]>
#> 1 2022-03-25-2022-06-18 227151 (1) ((150.2143 -34.00546, 150.2143 -34.01342, 15…
mapview::mapview(dat_wgs84)

# transform to original CRS (GDA94 / Geoscience Australia Lambert)
dat_gda94 <- st_transform(dat_wgs84, dat_crs)
dat_gda94
#> Simple feature collection with 1 feature and 2 fields
#> Geometry type: POLYGON
#> Dimension:     XY
#> Bounding box:  xmin: 1456105 ymin: -4173843 xmax: 1715909 ymax: -3755963
#> Projected CRS: GDA94 / Geoscience Australia Lambert
#> # A tibble: 1 × 3
#>   timestamp             sn                                              geometry
#> * <chr>                 <chr>                                      <POLYGON [m]>
#> 1 2022-03-25-2022-06-18 227151 (1) ((1486283 -3925744, 1486170 -3926615, 148575…
ggplot(dat_gda94) + geom_sf()

^{Created on 2023-08-09 with reprex v2.0.2}