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VinceE
Frequent Contributor
since
02-14-2020
a week ago
128
Posts created
69
Kudos given
11
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62
Kudos received
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My Ideas
(0 Idea Submissions)Latest Contributions by VinceE
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This is great, thanks for sharing this. For the fun of it, I rewrote to avoid using the nested cursors. I think a lot of this is a matter of style/opinion, but this separates the reading and editing from the writing, and also only sorts using the lambda function, rather than once with the SQL query and once with the lambda. It's basically the same as yours, it just creates a dictionary of updated values with the OID as the key, which enables writing in the correct order. This only uses two cursors (I believe you are recreating an UpdateCursor with every SearchCursor loop--I don't know how expensive that is). However, this version does have to create the intermediate dictionary. While I still think using the SQL query could be cleaner/easier to read, I assume it is slower because it forces the user to add and calculate a separate coordinate field (unless they have a spatially enabled geodatabase). Because the spirit of the question was specifically about using the SQL query, I am going to leave that as marked correct for posterity, but thanks all the input! from string import ascii_uppercase
from arcpy.da import SearchCursor, UpdateCursor
fc = r'PATH'
# Ensure OID and SHAPE are index 0 and 1.
fld = [f.name for f in ap.ListFields(fc) if f.type not in ['Geometry', 'OID']]
all_fld = [ap.da.Describe(fc)['OIDFieldName'], 'SHAPE@'] + fld
# ['OBJECTID', 'SHAPE@', 'LBL', 'XCOOR', 'YCOOR', 'GRP']
# Indices of fields, used to call specific values in cursor rows.
grp_idx = all_fld.index('GRP')
lbl_idx = all_fld.index('LBL')
# SQL WHERE:
where = f"""GRP IS NOT NULL AND TRIM(BOTH ' ' FROM GRP) <> ''"""
# Use Python sorted w/ lambda funct; update the given row; store in dict w/ OID key.
# Sort by GROUP, then DESC x-coor.
row_dict = {}
with SearchCursor(fc, all_fld, where) as scurs:
scurs_sort = sorted(scurs, key=lambda x: (x[grp_idx], -x[1].centroid.X))
for row in scurs_sort:
row = list(row) # Can't update SCurs tuple, unlike UCurs list
current_group = row[grp_idx]
try:
if current_group != previous_group:
letter_index = 0
except NameError:
letter_index = 0
row[lbl_idx] = ascii_uppercase[letter_index]
row_dict[row[0]] = row[1:]
letter_index += 1
previous_group = current_group
# Write the new row back to the same FC, using the OID as key again.
with UpdateCursor(fc, all_fld, where) as ucurs:
for oid, *_ in ucurs:
new_data = row_dict[oid]
ucurs.updateRow([oid, *new_data])
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11-04-2021
12:29 PM
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750
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Thanks for the input! This is close to the approach I would have used had I not gotten my SQL syntax sorted out, but @JoshuaBixby's comments would be issues with the Cursor. I think I would have had to use a SearchCursor, use sorted() with a lambda function (as you have done), and then use a separate UpdateCursor InsertCursor to write the sorted rows to a blank feature class with the same schema. Probably workable, but involves iterating over the same data more times (three total?) than necessary.
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11-04-2021
07:40 AM
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7
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4619
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Looks like this was a very clear issue of bad syntax on my part... here is sorting by three fields (all ascending, by default), by priority, in case someone else stumbles across this issue. sql_clause = (None, f"""ORDER BY {grp_fld}, {agency_fld}, {xcoor_fld}""")
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11-04-2021
06:50 AM
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4624
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I am trying to loop through an existing point feature class with an UpdateCursor (DA version) and assign consecutive labels (A, B, C, D...) to a field for features that fall within the same "group," which is a numbered attribute stored in another field. Lets call them the GROUP field and the LABEL field. I have accomplished this as follows, and it seems to work fine. It uses SQL's "ORDER BY GROUP," then increments through an alphabet string to assign the LABEL, then starts over at 'A' when the GROUP changes. from string import ascii_uppercase
from arcpy.da import UpdateCursor
fc = r'C:\Users\vce50\Desktop\Cursors\Cursors\Cursors.gdb\Random_Points'
fields = ['GRP', 'LBL']
where = f"""GRP IS NOT NULL AND TRIM(BOTH ' ' FROM GRP) <> ''"""
sql_clause = (None, 'ORDER BY GRP ASC')
with UpdateCursor(fc, fields, where, sql_clause=sql_clause) as ucurs:
for group, _ in ucurs:
current_group = group
try:
if current_group != previous_group:
letter_index = 0
except NameError:
letter_index = 0
new_lbl = ascii_uppercase[letter_index]
ucurs.updateRow([group, new_lbl])
letter_index += 1
previous_group = current_group The problem is that I would also like to order the labels spatially (north to south, for example), as a secondary sort after the GROUP. I am using a File GDB feature class, so I think that means no spatial SQL queries. I have also tried adding a Y_COOR field (DOUBLE type), and using that as a secondary SQL ORDER BY: sql_clause = (None, f"""ORDER BY {grp_fld} ASC; ORDER BY {y_coor} DESC""") However, I cannot seem to get this to work. It seems like only one ORDER BY query can be passed. Is that the case? I would prefer to do this in place with an UpdateCursor, but could also read all rows using a SearchCursor, sort with Python's sorted() and lambda function to order by multiple fields, and then write rows to a new blank feature class if the UpdateCursor won't work. Any recommendations would be appreciated!
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11-03-2021
05:40 PM
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11
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5463
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This is great, thanks Joshua. I'll dive into your blog post and check out these other methods. I appreciate you taking the time to explain this so clearly. In this case, since I'm reading/breaking down existing geometry objects, what would be your workflow here? The below line in my code is returning an array that represents the individual part of the multipart geometry (as expected): for i, part in enumerate(geom, start=1): I'm curious where you would go from here. As in my updated posting, doing the following works to retain the holes (nesting the "part" Array into another Array, then converting back a Polygon with the standard constructor): # Works:
exploded_polygon = ap.Polygon(ap.Array(part))
# Does not work, holes are not retained.
exploded_polygon = ap.Polygon(part) Is there a better method, where I take that existing "part" Array and handle it only with JSON? I guess I'm not sure how to get an existing arcpy.Array() into a format that can be used by either "AsShape" or "FromWKT." This is mostly an educational exercise at this point, since my update works, but I would definitely like to learn about more reliable methods of handling geometries. Thanks for your time!
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06-08-2021
09:21 AM
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5265
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In case someone else has a similar issue in the future: The solution to this was to nest the geometry "part" (which is already an Array) into another Array. Following this, the script works as expected. Full function below: def FeatureToPoint(in_fc, out_fc, point_location='CENTROID', explode=False):
"""
Creates a new feature class of points from input polygons or polylines.
:point_location:
CENTROID- The true centroid if it is within or on the feature;
otherwise, the label point is returned.
TRUE_CENTROID- The center of gravity for a feature.
LABEL- The labelPoint is always located within or on a feature.
:explode: create center point for each part? or just each feature?
"""
import arcpy as ap
import os
from arcpy.da import SearchCursor, InsertCursor
crs = ap.da.Describe(in_fc)['spatialReference']
ap.management.CreateFeatureclass(
out_path=os.path.dirname(out_fc),
out_name=os.path.basename(out_fc),
geometry_type='POINT',
template=in_fc,
has_m='', has_z='',
spatial_reference=crs)
flds = [f.name for f in ap.ListFields(in_fc)
if f.type not in ['Geometry', 'OID']
and f.name not in ['Shape_Area', 'Shape_Length']]
flds.insert(0, 'SHAPE@')
center_type = {'CENTROID': 'centroid',
'TRUE_CENTROID': 'trueCentroid',
'LABEL': 'labelPoint',}
with SearchCursor(in_fc, flds) as scurs, InsertCursor(out_fc, flds) as icurs:
for geom, *fields in scurs:
if explode:
for i, part in enumerate(geom, start=1):
"""
'part' is already an Array. Not clear why it needs
to be nested into another Array, but it does. Otherwise, only
the exterior ring of the part gets converted to a polygon,
excluding any internal rings.
"""
exploded_polygon = ap.Polygon(ap.Array(part))
# Testing/visualizing outputs:
#ap.management.CopyFeatures(exploded_polygon, fr'memory\Part{i}')
point_geom = getattr(exploded_polygon, center_type[point_location])
icurs.insertRow([point_geom, *fields])
else:
point_geom = getattr(geom, center_type[point_location])
icurs.insertRow([point_geom, *fields])
return out_fc
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06-07-2021
07:08 AM
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5285
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Thanks for the input Dan. I'm still a bit confused about this situation, however. I am (in theory, anyway) familiar with the way that ArcPy deals with geometry objects--the rings, and the Null points as separators. When I add the following print statement, I am getting the exterior rings, followed by the interior rings, all separated by the null points: (the first two lines are in the original post, and are just shown here for context) for geom, *fields in scurs:
for i, part in enumerate(geom, start=1):
print([array for array in part]) <---------LINE ADDED I won't paste in what it prints (because it's long), but an example is basically: [point, point, point, None, point, point, point, None, point, point, point] --> which is exterior ring, interior ring, interior ring. This describes that middle polygon shown in the image with the two holes. Based on this, the "part" variable contains all the rings that are necessary to create a polygon. So then why does my line below not create this polygon object, with these interior rings intact?: arcpy.management.CopyFeatures(arcpy.Polygon(part), fr'memory\Part{i}') You said, "when it is read, only the exterior ring is read." I don't follow what you mean here--if I was trying to get the .boundary() or something, that would make sense to me. But since the exterior and the interior rings are contained in the "part" object (evidenced by the print statement), why can't "part" be used to construct a Polygon object? The arcpy.Polygon() class doesn't read interior rings in this case? Would you be able to provide some code that would convert a polygon's part into a separate polygon? In regard to the difference between 'centroid', 'trueCentroid', and 'labelPoint'--my code here is part of a larger script that allows the user to supply any of these. The above snippet is just an example to make it easier for folks to help me solve this issue. For now, the centroid is sort of a moot point, it's really the polygon situation that I would like to understand. And as for MultipartToSinglepart--my goal is to learn about the inner workings of geometries, and why this isn't working the way I would expect it to. But you're right, I'll probably just revert to that once I (hopefully) learn why this approach is wrong. Thanks again for all your help.
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06-06-2021
06:20 PM
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5291
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I am attempting to generate a center point for each part of a multipart geometry. The issue I am having is that when reading multipart geometries (some with holes), the internal rings are not retained when reading/writing the individual parts. For testing, I am copying each part to a memory feature class (see images where holes are ignored). Because of this, the "labelPoint" property is not working as I would like it to. I am aware that I can use MultipartToSinglePart first, but I'd prefer to understand what part of this I'm not doing correctly, and handle the whole thing using Cursors. # IMPORTS------------------------------------------------------------------#
import arcpy
import os
from arcpy.da import InsertCursor, SearchCursor
# INPUTS-------------------------------------------------------------------#
in_fc = r'E:\SCRATCH.gdb\_MULTIPART_POLY'
out_fc = r'E:\SCRATCH.gdb\_CENTROID'
# MAIN---------------------------------------------------------------------#
# Create new output feature class.
arcpy.management.CreateFeatureclass(
out_path=os.path.dirname(out_fc),
out_name=os.path.basename(out_fc),
geometry_type='POINT',
template=in_fc,
spatial_reference=2248)
# Get relevant fields from the input FC to transfer. Add SHAPE@ token.
flds = [f.name for f in ap.ListFields(in_fc)
if f.type not in ['Geometry', 'OID']
and f.name not in ['Shape_Area', 'Shape_Length']]
flds.insert(0, 'SHAPE@')
# Read geometries, write centroids. Make TEMP copies of each geometry part.
with SearchCursor(in_fc, flds) as scurs, InsertCursor(out_fc, flds) as icurs:
for geom, *fields in scurs:
for i, part in enumerate(geom, start=1):
arcpy.management.CopyFeatures(arcpy.Polygon(part), fr'memory\Part{i}')
point_geom = getattr(arcpy.Polygon(part), 'labelPoint')
icurs.insertRow([point_geom, *fields]) The input polygon (one, multipart feature), followed by the output polygon parts and corresponding points: Input polygons. Separate output polygons, and corresponding label points.
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06-05-2021
08:48 PM
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5
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5352
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I have field teams that frequently need to take map areas offline while using Field Maps to collect data. I have found that once a map is set up to be taken offline, the hosted feature layers within that are editable are converted to WGS84--meaning, after the collected field data is synced, and then exported to a File Geodatabase, the spatial reference for this data will be WGS84. To be clear, these layers were originally published in our State Plane coordinate system (except the basemap, that's WGS84), and I do not have this same experience when using live syncing (NOT taking the maps offline). In cases where cell service is decent, and we don't need to set up maps as offline capable, the exported feature layers seems to maintain the original State Plane coordinate system that they started with when published. Can anyone confirm that this is expected behavior, and/or if there is a workaround? My guess as to what is happening is that an offline device cannot manage complex coordinate system transformations on the fly, so everything is transformed into Web Mercator once a map is "offline enabled."
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05-04-2021
06:28 AM
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4
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2250
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Eric, Did you ever get a resolution to this issue? I am finding something similar when taking photos using Survey123 on an iPad--regardless of orientation, the EXIF orientation tag is logged as 1.
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04-29-2021
02:45 PM
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3825
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Thanks for the quick reply Aaron. Fantastic, thanks, this has helped me get this to work in both Map Viewer and in the online interface for Field Maps. After a mobile reload, everything shows as expected. Some screenshots for posterity. This is within Map Viewer.
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04-23-2021
06:57 AM
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1
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9849
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I am unable to view all fields within a hosted feature layer when using the Field Maps app. These are fields that I have added after the initial push to an ArcGIS Online map, and after pulling this map up once in Field Maps (on mobile) to make sure it shows. I added one additional field through Pro, one through Map Viewer (the new version), and one using the Data tab for the hosted feature layer. In all three of the above places, I can then see these three additional fields. However they will not show up in Field Maps. Is there some way to toggle what fields display within the Field Maps app? Or refresh what shows somehow? Thanks in advance.
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04-22-2021
10:02 PM
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7
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9898
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I don't think this is the best way to create smooth, aesthetically pleasing contours. I have found the best approach is smooth the source data, rather than the contours lines. Try using Focal Statistics on your DEM (which I assume you have access to, since you referenced lidar) first, and THEN running contours.
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11-25-2020
11:56 AM
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3484
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Definitely a workaround, but I wish we didn't have to do this every time. It seems like deleting and recreating the legend will fix the issue (at least sometimes?), but I can't tell what triggers it to happen in the first place or what triggers it again after creating a new legend. Seems like a fresh, new bug for Pro; I don't recall dealing with legend issues as much in ArcMap, even if the GUI was a little confusing.
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10-26-2020
07:00 PM
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2774
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Thanks for the reply Tom Bole. I'd really appreciate you passing this along to the Layout team. Please let me know if this is something that gets logged. At the very least, it's frustrating that a legend will hop around when adjusting small formatting settings, and at worst, "Only show features visible in the map extent" is entirely unusable while generating a Map Series.
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08-31-2020
05:38 AM
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4786
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My kudoed posts
| Title | Kudos | Posted |
|---|---|---|
| 1 | 10-09-2024 08:46 AM | |
| 1 | 07-07-2020 01:01 PM | |
| 1 | 10-09-2024 07:22 AM | |
| 1 | 07-17-2024 02:57 PM | |
| 1 | 10-24-2024 07:51 AM |
Activity Feed
- Posted Re: Creating Lowercase "globalid" Fields on ArcGIS Pro Questions. a week ago
- Kudoed Re: Creating Lowercase "globalid" Fields for DavidSolari. a week ago
- Kudoed Re: Can't Sort Table on "Date_Only" Field Type? for KevinMacLeodEV. a week ago
- Posted Creating Lowercase "globalid" Fields on ArcGIS Pro Questions. a week ago
- Got a Kudo for Re: Serializing based on categories. 10-15-2025 03:55 AM
- Posted Re: Date Range Domain End Date of Current Date on ArcGIS Pro Questions. 08-13-2025 11:22 AM
- Posted Re: Date Range Domain End Date of Current Date on ArcGIS Pro Questions. 08-13-2025 11:10 AM
- Got a Kudo for Re: Calculating "None" Using Field Calculator Yields "WARNING 003571". 07-22-2025 05:39 AM
- Got a Kudo for Calculating "None" Using Field Calculator Yields "WARNING 003571". 07-22-2025 05:37 AM
- Kudoed Re: How to convert WKT polygon data in csv file into ArsGIS pro layer for logri-sl. 07-01-2025 07:03 AM
- Kudoed Re: How to convert WKT polygon data in csv file into ArsGIS pro layer for logri-sl. 06-25-2025 09:26 AM
- Kudoed Re: How to convert WKT polygon data in csv file into ArsGIS pro layer for DaveKim2. 06-25-2025 09:26 AM
- Got a Kudo for Re: How to convert WKT polygon data in csv file into ArsGIS pro layer. 06-09-2025 06:32 AM
- Got a Kudo for Cannot Apply Symbology From Layer Using Python Script. 02-20-2025 10:41 AM
- Got a Kudo for Cannot Apply Symbology From Layer Using Python Script. 02-20-2025 10:37 AM
- Got a Kudo for How to SelectByLocation, in memory, without adding to current map?. 01-28-2025 12:27 PM
- Got a Kudo for Re: Storing ELAPSED Time in Attribute Table?. 01-03-2025 10:16 AM
- Got a Kudo for Calculating "None" Using Field Calculator Yields "WARNING 003571". 01-03-2025 09:26 AM
- Got a Kudo for Re: Deleting a feature using arcade - help with code. 10-30-2024 02:49 AM
- Got a Kudo for Re: Select nearest polygons from point that sum to a value in the point. 10-28-2024 04:33 PM
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