how can i convert a shapefile to lat and lon boundaries?

Question

i have a shapefile of country subdivisions and i would like to extract an array of bounding lat and lon for each division.. is it possible to do?

Answer 1

Using the ogr Python module from OSGEO, this example will give you a tuple containing the coords that define an envelope for each feature.

from osgeo import ogr

ds = ogr.Open("mn_counties.shp")
lyr = ds.GetLayerByName("mn_counties")

lyr.ResetReading()

for feat in lyr:
    # get bounding coords in minx, maxx, miny, maxy format
    env = feat.GetGeometryRef().GetEnvelope()
    # get bounding coords in minx, miny, maxx, maxy format
    bbox = [env[0], env[2], env[1], env[3]]
    print env
    print bbox
    print

Answer 2

One possible way to proceed using SAGA GIS http://www.saga-gis.org After opening your shapefile run these 3 modules: 1. Modules\Shapes\Tools\Get Shapes extent

1. Modules\Shapes\Tools\Points\Points from lines [contrary to what the name suggest you can also use this to get points from a polygon]

2. Modules\Shapes\Tools\Points\Add Coordinates to points This will give you a table which contains the x and y coordinates of the 4 corners of the bounding box of your polygon file.

Answer 3

In arcgis, here's python code. result is a list of minx, miny, maxx, maxy, minM, maxM, minZ, maxZ (

import arcpy
for feat in arcpy.SearchCursor(r"c:\data\f.gdb\counties"):
    print feat.Shape.extent

-2.66852727251546 49.4265363633626 -2.52848181818121 49.5079454546192 NaN NaN NaN NaN
-10.463336363782 51.4455454544593 -6.01305454583045 55.3799909091533 NaN NaN NaN NaN
-4.77778181827614 54.0555454544593 -4.35347272688468 54.4100000000002 NaN NaN NaN NaN

Answer 4

Here's an R version, using example data from the rgdal package:

library(rgdal)
dsn <- system.file("vectors/ps_cant_31.MIF", package = "rgdal")[1]
d <- readOGR(dsn = dsn, layer="ps_cant_31")

## transform if this is not longlat
if (is.projected(d)) d <- spTransform(d, CRS("+proj=longlat +ellps=WGS84"))

for (i in 1:nrow(d)) {
  print(bbox(d[i,]))    
}