Hi Ashim,
Pls provide the exact link of what you're referring - this stuff is never
as much on the top of people's minds as we assume it to be.
Do try loading your shapefiles on other tools and check there :
mapshaper.org is a site that does a lot of quick, cool things with
shapefiles; QGIS is a software that does everything with shapefiles. Both
are free and open source.
The latter will help you re-save the shapefile into any CRS you want.
Right-click the layer > Save As (or "Export") and remember to choose your
preferred CRS in the dropdown.
Can you give background on what this CRS : *2154* : is and why you want to
transform to that? Because I've only come across two main CRS's both being
under the "WSG 84" category :
- EPSG 4326 : this makes everything in latitude longitude
- EPSG 3857 : this makes everything in meters from the equator (I think)
and we need to get the data in this format when we want to do things in
physical distance terms like making a 1km distance buffer or measuring areas
I haven't learned GIS stuff from theory, I just use it, so don't know more
details about CRS. I do understand that the dizzying multitude of CRS's out
there are so because apparently GIS folks like to re-orient the center of
the world (geometrically speaking) to where their data is to ensure least
distortion of their shapes in the rendering. When I come across anything
that's in a non-standard CRS, my first move is to transform it to either
lat-longs (4326) or meters (3857).
Regards
Nikhil VJ
On Monday, April 15, 2019 at 1:57:20 PM UTC+5:30, Ashim wrote:
>
> Dear All,
>
> I am referring to 2011_Dist. * set of shapefile. (District level
> shapefiles).
>
> When I read them as simple features in R, ( like this )
>
> map <- st_read("2011_Dist.shp") %>% st_as_sf()
>
> ( it's unprojected because it says 4326 in the epsg when I read the above )
>
> plot(map$geometry)
>
> it looks OK.
>
> But when I do :
>
> map <- st_read("2011_Dist.shp") %>% st_as_sf() %>% st_transform(crs= 2154)
>
> plot(map$geometry)
>
> the map is TILTED.
>
> What is the correct projection to use for this dataset? Please clarify.
>
> Best Regards,
> Ashim
>
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