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I'm using QGIS 2/12.3

I have a point layer with modelled data on a 1km grid, each point has a value (0-5, modelling temperatures) and lies at the centre point of a 1km grid square.

I also have a polygon layer which is of 1km squares.

I need to assign the points values to the corresponding polygons.

If I use intersect, the output layer is points, not polygons.

(I need to do this so I can intersect the km squares with another layer to find the average value for each polygon).

I realise one way might be to add a new column to the attribute table and paste data across - but I need some guidance.

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    Try completing a Spatial Join – MDHald Feb 29 '16 at 20:20
  • You may need to do a spatial join that joins the ids from the polygons to the points then do a database join to link the info back to the polygons using the Ids - hope this makes sense. – Sethinacan Mar 1 '16 at 10:34
  • Not entirely - I assume data management -> join attributes, but how to I join databases? – Stub Mandrel Mar 1 '16 at 17:06
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This is just a visual explanation of Join attributes by location.

(1) Let's assume you have a point layer (Point_temperature) with id and mod_temp fields.

(2) You also have a polygon layer (Grid) which has its own id field. (Note this id is unrelated with another id in the point layer.)

enter image description here

(3) Go to Vector | Data management | Join attributes by location.

(4) Make sure the Target is your Grid layer, and select Take attributes of the first located feature option.

(5) It will return a Joined layer (new polygon layer) in which you will see id_1 and mod_temp copied from the point layer.

enter image description here

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