Python Snippets

WoodyUmstead · ‎01-08-2026

I am new to Python and have a few tasks that my team has been encouraging me to do. So I am nervous and excited to get into this. Background: 3 years of JavaScript work that was mainly freelance. This is my first Job in GIS. First project is to build an automated "save edits" script to run after you start an edit session. So I am wondering, when building my test environment can I just set my 'save path' to somewhere on my local desktop and not to the server? So when I can see that it's saving correctly I can just change the path to our mapping server and bada bing bada boom? Also I believe a few packages need to be imported, and I am not sure If that will send a yellow or red flag to our IT dept. We are still new to using scripts and automating at my company. What are best practices you have found when building test environments? I feel silly, really, asking on here. I have spent a while searching for test environments specifically for ARCgis, and what we use is Futura, third party company that has some rebranded tools over ESRI software. Thank you and any info is good info for me right now.

JeffreyThompson2 · ‎07-29-2025

I have been struggling for several days trying to convert a legacy Python 2/ArcMap based script to run in the Python 3/ArcPro environment. It is a multi-step, data management script that involves clearing out the old data and putting in the new data. The script kept failing before a call to TruncateTable with "ERROR 000187: Only supports Geodatabase tables and feature classes." and/or at Compact with "ERROR 000535: Workspace does not exist." This didn't make sense since the data being feed to TruncateTable was a feature class and the Workspace being compacted did exist. And this script works just fine in the ArcMap runtime. We figured pretty early on that it was probably some sort of data locking issue or possibly something to do with the file path names being interpreted differently in the different flavors of Python. We tried writing our file paths differently, explicitly starting and stopping an edit session, and a bunch of other stuff. None of that worked. Then, I found a StackExchange answer that mentioned ClearWorkspaceCache. I threw arcpy.management.ClearWorkspaceCache() on the line before the TruncateTable and Compact calls and the script just worked. So the data was in fact being locked by the caching. Moral of the story: If you have a script that doesn't work and you don't know why and it's giving you errors that don't make sense, try ClearWorkspaceCache().

CristinaBurgosOtero · ‎06-18-2025

I am trying to iterate through the features of a layer and verify two different variables in two different fields in the same row. If both variables are true then it will apply a geoprocessing tool with one of the 2 results. The geoprocessing is Feature vertices to Point. I want to run it to create an output with points at the start of the line feature or on both sides of the line feature. I used already If/elif/else and it didn't work. I added the selection feature to apply the function of the geoprocessing tool to only the features that meet the conditions because without it it will apply it to all the lines in the layer once the condition was True in some of them and not just to the ones that meet the conditions. I tried this code and it works in separates blocks using notebook in ArcPro but when I put it all together it doesn't work. What do you think could be change to make it work? or what am I doing wrong here? import arcpy from arcpy import env arcpy.env.workspace = "workspace_gdb" feature_class = "Line_Feature_Class" output_vertices_topoint = "output_location" output_vertices_topoint2 = "output_location" value_x1 = "W" value_x2 = "N" value_x3 = "NW" value_y1 = "NS" value_y2 = "WE" field_name1 = "WindDegrees1" field_name2 = "WBDirection" domain_name = "Wind Direction" domains = arcpy.da.ListDomains(arcpy.env.workspace) target_domain= None for domain in domains: if domain_name == domain.name: target_domain=domain break if target_domain: # Create a dictionary of coded values. coded_values = domain.codedValues arcpy.management.MakeFeatureLayer(feature_class, "temp_layer") with arcpy.da.SearchCursor("temp_layer", ["SHAPE@", field_name1, field_name2]) as search_cursor: for row in search_cursor: object_id = row[0] coded_value1 = row[1] coded_value2 = row[2] if coded_value1 == value_y1 and coded_value2 == value_x3: # Select the feature arcpy.management.SelectLayerByAttribute("temp_layer", "NEW_SELECTION", f"{field_name1} = '{value_y1}' AND {field_name2} = '{value_x3}'") # Perform actions on the selected feature arcpy.management.FeatureVerticesToPoints("temp_layer", output_vertices_topoint, "START") else: print(f"Feature does not meet any condition.") arcpy.management.SelectLayerByAttribute(feature_class, "CLEAR_SELECTION") break with arcpy.da.SearchCursor("temp_layer", ["SHAPE@", field_name1, field_name2]) as search_cursor: for row in search_cursor: object_id = row[0] coded_value1 = row[1] coded_value2 = row[2] if coded_value1 == value_y2 and coded_value2 == value_x3: # Select the feature arcpy.management.SelectLayerByAttribute("temp_layer", "NEW_SELECTION", f"{field_name1} = '{value_y2}' AND {field_name2} = '{value_x3}'") # Perform actions on the selected feature arcpy.management.FeatureVerticesToPoints("temp_layer", output_vertices_topoint2, "START") else: print(f"Feature does not meet any condition.") arcpy.management.SelectLayerByAttribute(feature_class, "CLEAR_SELECTION") break with arcpy.da.SearchCursor("temp_layer", ["SHAPE@", field_name1, field_name2]) as search_cursor: for row in search_cursor: object_id = row[0] coded_value1 = row[1] coded_value2 = row[2] if coded_value1 == value_y1 and coded_value2 == value_x2: # Select the feature arcpy.management.SelectLayerByAttribute("temp_layer", "NEW_SELECTION", f"{field_name1} = '{value_y1}' AND {field_name2} = '{value_x2}'") # Perform actions on the selected feature arcpy.management.FeatureVerticesToPoints("temp_layer", output_vertices_topoint2, "START") else: print(f"Feature does not meet any condition.") arcpy.management.SelectLayerByAttribute(feature_class, "CLEAR_SELECTION") break with arcpy.da.SearchCursor("temp_layer", ["SHAPE@", field_name1, field_name2]) as search_cursor: for row in search_cursor: object_id = row[0] coded_value1 = row[1] coded_value2 = row[2] if coded_value1 == value_y1 and coded_value2 == value_x1: # Select the feature arcpy.management.SelectLayerByAttribute("temp_layer", "NEW_SELECTION", f"{field_name1} = '{value_y1}' AND {field_name2} = '{value_x1}'") # Perform actions on the selected feature arcpy.management.FeatureVerticesToPoints("temp_layer", output_vertices_topoint, "BOTH_ENDS") else: print(f"Feature does not meet any condition.") arcpy.management.SelectLayerByAttribute(feature_class, "CLEAR_SELECTION") break with arcpy.da.SearchCursor("temp_layer", ["SHAPE@", field_name1, field_name2]) as search_cursor: for row in search_cursor: object_id = row[0] coded_value1 = row[1] coded_value2 = row[2] if coded_value1 == value_y2 and coded_value2 == value_x2: # Select the feature arcpy.management.SelectLayerByAttribute("temp_layer", "NEW_SELECTION", f"{field_name1} = '{value_y2}' AND {field_name2} = '{value_x2}'") # Perform actions on the selected feature arcpy.management.FeatureVerticesToPoints("temp_layer", output_vertices_topoint, "BOTH_ENDS") else: print(f"Feature does not meet any condition.") arcpy.management.SelectLayerByAttribute(feature_class, "CLEAR_SELECTION") break with arcpy.da.SearchCursor("temp_layer", ["SHAPE@", field_name1, field_name2]) as search_cursor: for row in search_cursor: object_id = row[0] coded_value1 = row[1] coded_value2 = row[2] if coded_value1 == value_y2 and coded_value2 == value_x1: # Select the feature arcpy.management.SelectLayerByAttribute("temp_layer", "NEW_SELECTION", f"{field_name1} = '{value_y2}' AND {field_name2} = '{value_x1}'") # Perform actions on the selected feature arcpy.management.FeatureVerticesToPoints("temp_layer", output_vertices_topoint2, "START") else: print(f"Feature does not meet any condition.") print (row[1], row[2]) arcpy.management.SelectLayerByAttribute(feature_class, "CLEAR_SELECTION") break

DanPatterson · ‎04-09-2025

Yes... some more einsum examples.

DanPatterson · ‎04-01-2025

A followup to the recent einsum post, but with a field calculator twist # ---- a numeric field, python expression which uses the shape field to return the longest edge on the perimeter longest_seg(!Shape!) # ---- the code block ----- import json import numpy as np # def longest_seg(a): """Longest edge""" v = json.loads(a.JSON) r = v['rings'] a = np.array(r).squeeze() a = a[0] if a.ndim > 2 else a diff = a[1:] - a[:-1] ret = np.sqrt(np.einsum('ij,ij->i', diff, diff)) val = np.max(ret) return val lines 12-13 : really? having to convert to JSON format just to get at the array values? line 14 : the json format assumes a multipolygon so a nested, nested set of nests of values... numpy squeeze() gets rid of all the extra nesting line 15 : a check, but used for dimensions > 2, it will take the first part (the outer ring of the first shape) lines 16-17 : einsum .... read the previous article line 18: you will get an array of the segment lengths forming the perimeter... this demo is using the max, so modify the code if you want the minimum or the average or the 3rd from the end, etc etc. Just dont' over-fluff field calculator code to try and do everything line 19 return the value There really has to be a better way of converting an arcpy shape into another format which can be used without having to use cursors and deal with the featureclass rather than the feature itself. like make __geo_interface__ read the shape without having to use that in cursors.

Python Snippets

Python Snippets

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Python Snippets