I am having a shape file of polygons and another CSV file which contains a list of points as (Lat, Lng) pairs..
I want to check for each (lat, lng) pair from the CSV file which polygon does it fall inside..
The shape file is projected and the proj file reads like this..
PROJCS["Transverse_Mercator",GEOGCS["GCS_OSGB 1936", DATUM["D_OSGB_1936",SPHEROID["Airy_1830",6377563.396,299.3249646]],PRIMEM["Greenwich",0],UNIT["Degree",0.017453292519943295]],PROJECTION["Transverse_Mercator"],PARAMETER["latitude_of_origin",49],PARAMETER["central_meridian",-2],PARAMETER["scale_factor",0.9996012717],PARAMETER["false_easting",400000],PARAMETER["false_northing",-100000],UNIT["Meter",1]]
My plan is as fllows:
- Read the shape file using the
readShapePolyfunction in the R
- Read the points coordinates from the CSV file into a dataframe and convert it to SpatialPointsDataFrame
overfunction to determine which polygon it falls inside.
In order to do so,, I need to specify the
proj4string while loading the shape file in step 1 and also transform the coordinates from the CSV file into the same projection system using
spTransform function before applying the
over function in step 3 as it requires that the points and polygons must be under the same projection system.
Any idea about what should the correct value for the proj file content shown above ?