topic Re: Sorting Issue in Python Questions

Sorting Issue

TonyAlmeida — Tue, 26 Oct 2021 18:18:57 GMT

I have a shapefile that I am trying to sort a specific field but for some weird reason it changing the shape of the features, . The following does short the field I want but it is making the features bigger. I am not sure why this is happening?

BPs ="BPs1" data = [] with arcpy.da.SearchCursor(BPs,"*") as cursor: for row in cursor: data.append(row) data.sort(key=lambda tup: tup[21]) # sorts based on the 21st field count = 0 with arcpy.da.UpdateCursor(BPs,"*") as cursor: for row in cursor: row = data[count] count += 1 cursor.updateRow(row)

Re: Sorting Issue

JoshuaBixby — Tue, 26 Oct 2021 18:30:52 GMT

Can you elaborate on "it is making features bigger?" And can you give an example?

Re: Sorting Issue

TonyAlmeida — Tue, 26 Oct 2021 18:40:06 GMT

The first image is what the actual feature should be but after I run the sort I post it sorts the features but changes the shape, makes them bigger.

Re: Sorting Issue

JayantaPoddar — Tue, 26 Oct 2021 18:40:34 GMT

Did you try Sort (Data Management) instead?

Re: Sorting Issue

TonyAlmeida — Tue, 26 Oct 2021 18:42:23 GMT

I was trying to use the arcpy.da.UpdateCursor because I need to add an increment to the features that are sorted.

Re: Sorting Issue

JoshKalovGIS — Tue, 26 Oct 2021 19:05:53 GMT

I don't know if this would cause your issues but I would recommend specifying the field names (searchcursor and updatecursor docs recommend this) and using SHAPE@ for the geometry because it returns a geometry object which is less likely to get rounded or manipulated.

So above your SearchCursor I would add a line:

fields = [f.name for f in arcpy.ListFields(BPs)] fields = fields - ['Shape'] + ['SHAPE@']

And then in your SearchCursor and UpdateCursor, pass the fields variable instead of "*"

Re: Sorting Issue

Anonymous User — Tue, 26 Oct 2021 21:23:37 GMT

You can also sort within the cursor using the sql clause so you could probably avoid having to create that sort list,

Edited: but it lookes liek you are trying to created a sorted featureclass I'd probably create a new featureclass instead of updating the old.

with arcpy.da.UpdateCursor(BPs,fields, sql_clause=(None, ' ORDER BY ' + field + ' DESC'), where_clause=(field + ' IS NOT NULL')) as cursor: count=0 for row in cursor: row[0] = count # or other calc based on what you need. count += 1 cursor.updateRow(row)

or to create the sorted list:

data = [row for row in with arcpy.da.SearchCursor(BPs,"*", sql_clause=(None, ' ORDER BY ' + field + ' DESC'), where_clause=(field + ' IS NOT NULL'))]