Projecting my shapefile data on leaflet map using R

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鱼传尺愫
鱼传尺愫 2021-02-02 04:39

I (on Win7) was trying to get my shapefile data (Here are the data files.) to be displayed using leaflet package. But without any success. I only get the background

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  • 2021-02-02 04:50

    Hi you have to change the projection :

    library("rgdal")
    shapeData <- readOGR(".",'myGIS')
    shapeData <- spTransform(shapeData, CRS("+proj=longlat +ellps=GRS80"))
    library("leaflet")
    leaflet()  %>% addTiles() %>% 
      setView(lng = -106.363590, lat=31.968483,zoom=11) %>% 
      addPolygons(data=shapeData,weight=5,col = 'red') %>% 
      addMarkers(lng = -106.363590,lat=31.968483,popup="Hi there") 
    

    But I can't tell you why this works, i only know a little about geo and proj.

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  • 2021-02-02 05:00

    The answer of Victorp works. However I would suggest to use:

    shapeData <- spTransform(shapeData, CRS("+proj=longlat +datum=WGS84 +no_defs"))
    

    This CRS corresponds to EPSG:4326. Leaflet actually takes care of transforming from EPSG:4326 to EPSG:3857 (known as "Google Mercator").

    Now, the difference (GRS80 vs WGS84) is negligible (0,1 mm on one of the axis). And it seems that leaflet considers both to be the same Ellipsoid. However for test purposes would be advisable to have EPSG:4326.

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