I am using QGIS 3.2.0 on a Mac (and also have QGIS 2), and I have a fishnet grid (probably created in Arc) that comprises of nearly 2 million grid cells. As a result, every change I make to the attribute table takes hours, so I can't experiment as I would usually.

I need to label each grid cell such that the north-westernmost cell is "1", and the numbers proceed by rows, until the last number goes into the south-easternmost cell. Using the row-number doesn't work, as that's not how the table is sorted. I've done this before, but cannot remember how.


You can use pyqgis.

Script will:

  1. List all centroids x, y coordiantes with each features id
  2. Sort list by x and y
  3. The ids are now in correct order - create a dictionary of id and sequential number using enumerate: attrMap = {feature id: {field index: order}, ...}
  4. Use dictionary with id as key and update field

Add your layer to the map, add a integer field to hold the numbers and execute.`

layer = iface.activeLayer() #Click layer in layer tree
idfield = 'fishnetID' #Change to match the name of your field

coords = [[round(f.geometry().centroid().asPoint().x(),0),round(f.geometry().centroid().asPoint().y(),0),f.id()] for f in layer.getFeatures()]
coords.sort(key=lambda k: (k[1],-k[0]), reverse=True)
order = [i[2] for i in coords]

i = layer.fields().indexFromName(idfield)
attrMap = {id: {i:e} for e,id in enumerate(order,1)}

enter image description here

  • 1
    Worked like a charm. Thanks. May 10 at 16:40

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.