[QGIS-ZA-user] aggregate crime attribute data from SAPS Station boundaries to Wards

[Arthur TAUTE]

Hi,
I would do it in PostGIS as a first choice by finding the appropriate function.
In QGIS I guess one needs to use the intersection tool and then load the result into a spreadsheet and do a pivot table per ward

Regards

Arthur Taute | Chief Technical Principal
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From: qgis-za-user [mailto:qgis-za-user-bounces at lists.osgeo.org] On Behalf Of Tim Sutton via qgis-za-user
Sent: 02 October 2018 01:38 PM
To: South Africa QGIS user group <qgis-za-user at lists.osgeo.org>
Cc: Tim Sutton <tim at kartoza.com>
Subject: Re: [QGIS-ZA-user] aggregate crime attribute data from SAPS Station boundaries to Wards

Hi Brian

This should be fairly easy to do in QGIS without using any special plugins if you don’t mind doing a few steps. Can you share the datasets you want to use with me and I will see if I can come up with an easy workflow for you?

Regards

Tim


On 02 Oct 2018, at 10:57, Brian O'Leary via qgis-za-user <qgis-za-user at lists.osgeo.org<mailto:qgis-za-user at lists.osgeo.org>> wrote:

Dear QGis SA,

I would like to know if there is a QGis tool that can assist with the following task.  I want to transfer crime attribute data from SAPS Station boundaries to Ward boundaries, assuming that crime is evenly distributed within the SAPS Station boundary.

Previously I have done this task in Arc View using a script called DataPart.avx which was written by Jianwei Dou in 2002.  The below simplified sketch illustrates what I am trying to do in Qgis.  The SAPS Station shape has the data attributes and the Ward shape is the overlay or boundary shape. The output that I need is an attribute table that has calculated the % intersection of the SAPS Station by the ward boundaries and aggregated the crime attributes to a Ward table based on the % intersection.  In the below sketch the ward boundaries intersect the SAPS Station boundary by 50% in both cases.  As there were 100 crimes in the SAPS Station boundary the output table lists Wards 1 and 2 with 50 crimes in each.

<image.png>
Any advise most welcome.

Regards
Brian O'Leary



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