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I have a set of farms which are assigned to grid squares and the exact coordinates are unknown.

I also have a layer which subdivides the grid squares according to topographic, climate conditions etc... in each of these categories. Each farm falls in one of these categories which is known from the dataset.

How can I assign the farms into points that are randomly somewhere in the grid square and also in the subdivided topographic area?

For instance, in the Example 1 , it is known that the farm belongs to upland area (green area). So how do I reallocate it in the green area that falls within the grid square boundaries?

Example

  • Thanks again for the suggestions. I ve followed the instructions for the first approach by Hornbydd. I have cutted up the land type and placed the centroids however, I cant figure out how to reallocate a farm on a centroid, according to the code of land that it has. Please note that my sample has more than 300 farms so I d have to do this automatically. Please see attachment in scontent.xx.fbcdn.net/v/t1.0-0/s480x480/… – George Vittis Nov 21 '16 at 15:42
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First step is to run a Union on your data using the grid and land category layer. This would cut up your land use data by grid square, so in your example you would get a polygon that is the majority of your grid square coming from your blue category land class and a smaller one from the green.

The Union process carries over all attributes, so the output will have the grid square ID.

So knowing your farm point is in grid ID X and that it should be in land class Y you would simply extract the centroid of the land class Y and tag that as your farm.

Now do you have scenarios such as multiple farms in a grid cell on the same land class? My suggestion would then stack farms on top of each other...

  • Thanks for the suggestion. I will give it a go and let you know. As for the stacking it is not the best solution as I am using then interpolation methods and I will be loosing spatial variation from the different performances that coinciding points (farms) have – George Vittis Nov 18 '16 at 16:23
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    +1 . Perhaps count no of farms per grid/land cover. Transfer count to intersect polygons. Create n random points inside each and add geometry attributes. Join points table to farms and use gis.stackexchange.com/questions/159206/… to move faems – FelixIP Nov 18 '16 at 19:08
  • Thanks again for the suggestions. I ve followed the instructions for the first approach by Hornbydd. I have cutted up the land type and placed the centroids however, I cant figure out how to reallocate a farm on a centroid, according to the code of land that it has. Please note that my sample has more than 300 farms so I d have to do this automatically. Please see attachment in scontent.xx.fbcdn.net/v/t1.0-0/s480x480/… – George Vittis Nov 21 '16 at 15:46

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