Creating Unique IDs of points in order from west to east

Question

I have a dataset with over 1000s points. I am wondering if I am able to give each point a unique ID starting from west to east.

I am using ArcMap 10.6. Is there a way to do this in ArcMap?

Calculate new field xcoordinate > sort by xcoordinate > add new numeric field "seq" > fill field seq with counter see: https://gis.stackexchange.com/questions/193681/calculating-sequential-numbers-into-sorted-table-using-arcgis-desktop — Hans Erren, Dec 07 '20 at 20:45
A simple sort on easting and northing (descending) should work for this, though you might get more methodical results with large datasets if you use a grid to bin values first. See https://gis.stackexchange.com/questions/73978/numbering-polygons-according-to-their-spatial-relationships — Vince, Dec 07 '20 at 21:45
Check How To: Create sequential numbers in a field using Python in the Field Calculator — ahmadhanb, Dec 07 '20 at 22:30
The solution in the link takes into account OID order, I guess. — Kadir Şahbaz, Dec 07 '20 at 23:46
The Sort (management) gp tool will produce a sorted fc. You can set the sorting to be from left to right (cartesian). Then use the Create sequential number using Calc Field as stated above. — gotchula, Dec 18 '20 at 00:29

score 7 · Answer 1 · answered Dec 07 '20 at 23:28

7

First, to be sure POINT_X has no duplicate values, run next two lines in Python console.

# change layer_name
x_values = [row[0] for row in arcpy.da.SearchCursor("layer_name", "POINT_X")]
len(x_values) == len(set(x_values)) # output should be True

If POINT_X has no duplicate values you can use the following script in Field Calculator.

Open Field Calculator (by right click on seq field)

Populate the parameters as in the image using the following script. (Don't forget to change layer_name in the script)

x_values = [row[0] for row in arcpy.da.SearchCursor("layer_name", "POINT_X")]
x_values.sort(reverse=True)
def add_unique_ids(x):
    global x_values

    i = x_values.index(x)

    return i

And call the method.
```
add_unique_ids(!POINT_X!)
```

The main limitation is that features with the same POINT_X get the same seq value. I couldn't figure it out yet.

answered Dec 07 '20 at 23:28

Kadir Şahbaz

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I'm not sure. Give it a try. I have set seq as integer. – Kadir Şahbaz Dec 08 '20 at 00:06
Yes. I've tried something for duplicate values but I couldn't solve. – Kadir Şahbaz Dec 08 '20 at 00:09
I got that error. Make sure you typed the layer and field names in SearchCursor. – Kadir Şahbaz Dec 08 '20 at 00:20
1

I think this is related to the data resolution, i.e., number of digits of X coordinate that you receive from ArcGIS and how they are saved in a python list. As a workaround, you can use round builtin function of python. In this answer, if you change row[0] to round(row[0], 4) and x_values.index(x) to x_values.index(round(x ,4)), you would be fine. Here, the value of 4 is arbitrary and presumed it will work in a projected CS. – fatih_dur Dec 08 '20 at 00:32
I thought that. In your case, it would be fine. But it may return incorrect results for geographic coordinates. – Kadir Şahbaz Dec 08 '20 at 00:35
you could also export the attribute table to excel, do a sort and sequence fill there and join the result based on fid – Hans Erren Dec 08 '20 at 13:51

Creating Unique IDs of points in order from west to east

1 Answers1