Sorting points based on Northing and Easting

Question

I have around 1320 point/centroid features in a shapefile for my research plots. Each point/centroid has X and Y coordinate associated with them which were calculated using Field Calculator > Geometry > $X $Y in QGIS. At present the reference IDs are in no particular order. But eventually I would like to create a new attribute column by the order shown in the below image. .

At first I tried to sort my points by X and Y (selecting 10 consecutive points at a time) but due to fact that all points in a single row don't lie on the same northing or easting line, the plot order was not proper.

So I would like to know if there is a neat way to sort these points spatially (X and Y) and then assign a sequence ID in the order as shown in the image.

Answer 1

It may be not the "neat way" what you have asked for, but i would go for this if i have a lots of points (but you have only 1400(c) points).

1. Separate each block ( in your image there are three blocks) using arcmap fishnet tool or others.
2. Now run following operation on every block (for your image the rightmost block where 90 points are in place)

3. Run sort tool, use "Shape" field with "Ascending" and select "UR" at first and "Descending" for second with same other setting.This will create two featureclasses one is "Left to Right" and "Top to Bottom" another "Right to Left" and "Bottom to Top" in terms of feature alignment.

4. Now assign an attribute for each row- you may use following field calculator code (this adds 1,2,3 etc for each column e.g all points in a row with attribute value of one.).

   flg = 0
   def x(f):## Where f is objectid of any sequential field
       global flg
       if math.fmod(int(f),38)==1.0: ## for my case 38 is the point in each row
           flg+=1
           return flg
       else:
           return flg
   

5. Then delete "Odd" flagged rows from "Ascending" featureclass and "Even" from "Descending" featureclass (you have got two feature classes with opposite direction but there is no change in the attribute)

6. Now run "Merge" tool for these two featureclasses which return back the original featureclass but with that "ZIGZAG" direction.

7. Apply these methods for other blocks.

N.B. All these can be automatized with better understanding