nav[aria-label="Primary Navigation"] { padding: 0; & ul { list-style: none; width: 100%; display: flex; flex-direction: row; justify-content: start; align-items: start; gap: 30px; padding: 0; & li { margin: 0; } & ul li { list-style: none; } } }

Calculating the Max N/S/E/W of polygon

Emma_Cunliffe

Hi all

I have ARC 10.2.1.

I have a shapefile of polygons, and the I need the maximum N / S / E / W points for each polygon (not the centre point)

Is there a way to do this?

(I can use the tools etc, but have no knowledge of scripts or anything like that, so I would need some pretty basic instructions if that's what's required)

(Geometric attributes / extent only gives 2 max/min extents which do not reflect the actual shape of the polygon, not all 4)

Thanks

Find more posts tagged with

Accepted answers

All comments

FC_Basson

Same question and answer here: coordinates of the extents of a polygon

The extent automatically refers to the feature's maximum N/E/S/W coordinates.

Emma_Cunliffe

Hi, same reply, but I couldn't figure out how to turn off "assumed answered"
I really appreciate your help, and I may have a fundamental misunderstanding, and am happy to be corrected, but it seems that no - it doesn't.

If you assume, for the sake of argument, your shape is diamond, it gives you the bottom left coordinate and the top right coordinate as if someone had drawn a square around your shape, and given you only those two points. So it doesn't give all 4 points, and the 2 points it does give are not actually in the polygon?

FC_Basson

Ok so you actually need the maximum COORDINATE of the maximum bounding extent points

Emma_Cunliffe

Yes, the "maximum N, S, E and W points"

DanPatterson_Retired

if you have shapefiles, use the Minimum Area Bounding Rectangle option of Bounding Containers, the axis dimensions are contained in the table which you can join back to you shapefile if needed

Emma_Cunliffe

Thanks but as above, I need points that are part of the polygon, not the points of a container which (given the irregular shapes of my polygons) are not actually located within the shape

DanPatterson_Retired

sorry, misread... you need the extent then, which can be done in the field calculator since it will produce the min x, max x, min y, max y

These won't formulate a point, but if you need the minimum X regardless of y and max X regardless of y and their y equivalents, then that is different

FC_Basson

Hi Dan Patterson, yes I think Emma wants the coordinate/point for the vertice that represents each side of the bounding extent.

DarrenWiens2

Here's how you can do it using Python:

1.) Add fields to polygon feature class (could also do in Python, if you want):

2.) Run script

>>> fc = 'all_aoi' # change to your layer name or feature class path
... fields = ['SHAPE@','N_X','N_Y','E_X','E_Y','S_X','S_Y','W_X','W_Y'] # pay attention to order
... with arcpy.da.UpdateCursor(fc,fields) as cursor: # loop through polygons
...    for row in cursor: # for each polygon
...        N = arcpy.Point(0,float('-inf')) # dummy coordinates
...        E = arcpy.Point(float('-inf'),0) # dummy coordinates
...        S = arcpy.Point(0,float('inf')) # dummy coordinates
...        W = arcpy.Point(float('inf'),0) # dummy coordinates
...        for part in row[0]: # loop through polygon parts
...            for pnt in part: # loop through vertices
...                if pnt.Y > N.Y: # test coordinates
...                    N = pnt # remember coordinates if vertex is more extreme               
...                if pnt.X > E.X: # test coordinates
...                    E = pnt # remember coordinates if vertex is more extreme
...                if pnt.Y < S.Y: # test coordinates
...                    S = pnt # remember coordinates if vertex is more extreme
...                if pnt.X < W.X: # test coordinates
...                    W = pnt # remember coordinates if vertex is more extreme
...        new_row = [row[0],N.X,N.Y,E.X,E.Y,S.X,S.Y,W.X,W.Y] # build new row data, same order as fields list
...        cursor.updateRow(new_row) # write row

Join the Conversation

Signed in members can post, follow updates, and more. New here? Register a free account.

Quick Links

Community Help
Find useful guides, FAQs, and documents to help you navigate and make the most of Esri Community.