M.Laloux mlaloux

Author: Sean Gillies Version: 1.0

Abstract

This document describes a GeoJSON-like protocol for geo-spatial (GIS) vector data.

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	I return to this issue because it is very similar to How do I find vector line bearing in QGIS or GRASS? and it can be solved with Python in the same way:

	1) Haversine distance

	One can find lots of scripts by searching Haversine distance with Python on the Internet and I choose one of them in Haversine Formula in Python (Bearing and Distance between two GPS points)

	def haversine(lon1, lat1, lon2, lat2):
	"""
	Calculate the great circle distance between two points

	If you want to use Python, you don't need QGIS, except if you want to create a plugin. In this case, you should consider PyQGIS with the reference given by Curlew

	But you can also use Python modules like pyshp, osgeo (gdal and ogr) or Fiona and Shapely without QGIS

	In both cases, you need a join field that will link the polygon shapefile to the point shapefile.

	Example with Fiona and Shapely (all the elements of a shapefile (schema,geometry, records) are processed using Python dictionaries).

	With ogr and Fiona it is easier to create a new shapefile, copying the original shapefile (geometry and attributes), and adding new fields with the desired values than modify the original shapefile.