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I have a list of UK postcodes and a number of participants in a survey. I would like to map the first three letters of the UK postcode and I would like a shape....a circular shape for example which will show a figure and its size is relative to the figure, ie. 50% is half the size of 100% in each postcode area. This will show how many people participated from different areas.

I am totally new to QGIS and I was hoping that I could get a link to either a guide on how to do this, or link to practice data together with a step-by-step guide.

PolyGeo
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Winter
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    Two questions to clarify what you already have: Are the postcodes and survey already spatial data? And does the list of survey participants have the postcode for each survey? – Micha Jul 05 '15 at 07:24
  • The free data from https://www.ordnancesurvey.co.uk/business-and-government/products/code-point-open.html is already spatial. See also http://gis.stackexchange.com/questions/85631/uk-postcode-boundaries?rq=1 if you want polygons. – AndreJ Jul 09 '15 at 07:54
  • using the opendata csv you can create postcode polygons using GRASS [GIS] here is an example https://www.r-bloggers.com/gb-postcode-polygons-open-data/ *links to a 2018 created dataset – Mapperz Jun 17 '20 at 21:51
  • I reopened this tread again because the first answer was too general to answer correctly to the innitial question. I am in the same situation so i'm providing another solution and in the same time asking for new answers Thank you for your understanding – Honk Jun 19 '20 at 07:59

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Assuming you have a spatial table for post codes and a .csv containing number of participants with a name or id that is common to both the spatial file and the .csv, the following tutorial will enable you to create a spatial file of the required data: http://www.qgistutorials.com/en/docs/performing_table_joins.html

If your new postcode file is not points then you need to use the following answer to get centroid points from postcode polygons: How to determine the centroid of polygons?

Once you have your points you can use the "Layer Properties" dialogue to create your desired circles (use "Graduated" in style) see http://docs.qgis.org/2.0/en/docs/training_manual/vector_classification/classification.html

Create labels (use the expression: left( "Postcode_name_field" ,3) to get the first three characters of the postcode name - see my favourite: Learning to use expressions in QGIS?

til_b
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Tim in Kyneton
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