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I am using QGIS to map a number of radio antennas (for mobile network). Once I have the layer of the sites (done), I would like to assign to each site a coverage area (envelope). I could achieve that using the "fixed distance buffer" function of fTools

However, I couldn't make the envelope have a Hexagon shape.

When I specify the number of segments: 1: I obtain a square 2: I obtain an octagon ...

How can I do to have a Hexagon?

Thank you

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I don't know of a plugin that does hexagons and I also can't enter a value of less than 5 in the buffer tool so I can't reproduce what you see. There is a tool which will do squares, diamonds and oval buffers, but again that's not really what you're after. I suspect you will need to do a little scripting. – MappaGnosis Jan 4 '13 at 14:41

As MappaGnosis indicated, you could write a little script for this. Here's one called polygonbuffer which takes three arguments: The output file name, the radius of your buffer, and the number of corners of the polygons.

Open a Python console in QGIS, paste the script and press enter to define the function, then call using something like polygonbuffer("polygons.shp",50,6) to get hexagons with a radius of 50 map units:

import numpy as np
def polygonbuffer(outputFilename, bufferLength, polygonSides=6):
 layer = qgis.utils.iface.activeLayer()
 provider = layer.dataProvider()
 fields = provider.fields()
 writer = QgsVectorFileWriter(outputFilename, "CP1250", fields, QGis.WKBPolygon,, "ESRI Shapefile")
 inFeat = QgsFeature()
 outFeat = QgsFeature()
 inGeom = QgsGeometry() provider.attributeIndexes() )
 while provider.nextFeature(inFeat):
  point = inFeat.geometry().asPoint()
  inGeom = inFeat.geometry()
   [[QgsPoint(point[0]+np.sin(angle)*bufferLength, point[1]+np.cos(angle)*bufferLength)
     for angle in np.linspace(0,2*np.pi,polygonSides, endpoint=False)]]))
  outFeat.setAttributeMap( inFeat.attributeMap() )
  writer.addFeature( outFeat )
 del writer
 newlayer = QgsVectorLayer(outputFilename, "Polygons", "ogr")

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