topic Re: In ArcMap Pro, how to get data from a selected layer in Python Questions

In ArcMap Pro, how to get data from a selected layer

jasongraham — Sat, 11 Dec 2021 06:06:19 GMT

I am using python in ArcPro and relearning a few things.

I have a feature selected in the dataframe. I want to determine the name of that layer that has a selection and return the value of the selected object in the field called "GNIS_Name" .

aprx = arcpy.mp.ArcGISProject("CURRENT")

#get selected layer 
m = aprx.listMaps(aprx)
refLyr = m.listLayers(aprx) 
sel_lyrs = refLyr.getSelectionSet(aprx)

# get name of selected stream    
Stream_Name = arcpy.da.SearchCursor(sel_lyrs, "GNIS_Name", "Any value", "")‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

currently I get the error on line 5: 'list' object has no attribute 'listLayers'

Re: In ArcMap Pro, how to get data from a selected layer

JoshuaBixby — Sat, 11 Dec 2021 06:06:22 GMT

aprx = arcpy.mp.ArcGISProject("CURRENT")
m = aprx.activeMap
lyrs = m.listLayers()
for lyr in lyrs:
    if lyr.getSelectionSet():
        print("{}: {}".format(lyr.name, lyr.getSelectionSet()))
‍‍‍‍‍‍

Re: In ArcMap Pro, how to get data from a selected layer

jasongraham — Tue, 30 Apr 2019 19:01:10 GMT

Thanks, this gets me a few steps closer.

Re: In ArcMap Pro, how to get data from a selected layer

jasongraham — Wed, 01 May 2019 18:56:58 GMT

However, in my next step, I want to take the name of that selected layer and get a field value

Stream_Name = arcpy.da.SearchCursor(lyrs, "GNIS_Name", "Any value", "")‍‍‍‍

I get the error

RuntimeError: 'in_table' is not a table or a featureclass

Am I taking the wrong approach? it seems to pass as a layer and not a feature class.

Re: In ArcMap Pro, how to get data from a selected layer

JoshuaBixby — Wed, 01 May 2019 19:23:42 GMT

There appears to be quite a bit going on, or going wrong, with your search cursor syntax. Starting with the first parameter, you are passing lyrs, which is a list. ArcPy cursors can't operate on Python lists. The second parameter seems OK, assuming "GNIS_NAME" is the name of the field in question. I am unclear what you mean by "Any Value" for the third parameter. The third positional parameter is an SQL WHERE clause, and I am not sure how to interpret what you are passing.

Re: In ArcMap Pro, how to get data from a selected layer

jasongraham — Sat, 11 Dec 2021 06:06:25 GMT

well I am learning a lot of ways not to do it. This statement will print the all the names, not just the selected row

aprx = arcpy.mp.ArcGISProject("CURRENT")
m = aprx.activeMap
lyrs = m.listLayers()
for lyr in lyrs:
    if lyr.getSelectionSet():
       sel_lyr = lyr.dataSource
       sel_oid = lyr.getSelectionSet()
       with arcpy.da.SearchCursor(sel_lyr,"GNIS_Name") as cursor:
           for row in cursor:
               print(row)‍‍‍‍‍‍‍‍‍‍

All I want is to know the path of the layer that has a selected feature, and know what the name is in the "GNIS_Name" Field of that selected feature

the lyr.getSelectionSet will give me the data source and the OID of the selected row.

I have tried to use an SQL in the search cursor like this

with arcpy.da.SearchCursor(sel_lyr,"GNIS_Name",'OID@' = sel_oid) as cursor:‍

and many variations like that, but always get a syntax error. is my entire approach wrong?

I orignially did the project in MB but elected to move to Python. I essentially need a Get Field Value function.

Re: In ArcMap Pro, how to get data from a selected layer

JoshuaBixby — Fri, 03 May 2019 02:08:12 GMT

ArcPy cursors honor selection sets on layers and table views. Instead of retrieving the the data source of the layer and passing that to the cursor, just pass the layer itself.

Re: In ArcMap Pro, how to get data from a selected layer

RandyBurton — Sat, 11 Dec 2021 06:06:28 GMT

# instead of OID@
with arcpy.da.SearchCursor(sel_lyr,"GNIS_Name",'OID@' = sel_oid) as cursor:

# try OBJECTID or the field's actual name instead of a token
# also note the quotes around the sql part
with arcpy.da.SearchCursor(sel_lyr,"GNIS_Name","OBJECTID = sel_oid") as cursor:‍‍‍‍‍‍‍‍‍‍‍‍

Re: In ArcMap Pro, how to get data from a selected layer

jasongraham — Sat, 11 Dec 2021 06:06:30 GMT

Thanks for the help! This is what works:

import arcpy
aprx = arcpy.mp.ArcGISProject("CURRENT")
m = aprx.activeMap
lyrs = m.listLayers()
for lyr in lyrs:
    if lyr.getSelectionSet():
       sel_lyr = lyr.dataSource
       field = "GNIS_Name"
       rows = arcpy.da.SearchCursor(lyr,field)
       for row in rows:
            print(row[0])‍‍‍‍‍‍‍‍‍‍‍

now off for the rest of the code....

Re: In ArcMap Pro, how to get data from a selected layer

jasongraham — Sat, 11 Dec 2021 06:06:34 GMT

I should probably start a new question, by thought I would check here first. This code will run all the way through, all the fields gat added but the one at line 139 with the code block does nothing and I dont get any errors. I have tried changing the " to ' changing all the quotes and do not see any changes.

am I doing the codeblock wrong?

# -*- coding: utf-8 -*-

'''---------------------------------------------------------------------------
# Exposed.py
# Created on: 2019-04-10 Jason Graham
#
# Usage: For classifying hazard level from winds on cops of trees near 
# Anadromous streams Primary and secondary previaling winds.
# 
# Paramters <Workspace> 
#           <Prevailing_Wind_Direction> 
#           <Secondary_Prevailing_Wind_Direction>  
#           Selected Stream with a GNIS_Name field
#
# Description:
# When a stream is selected this tool will create a buffer for each side of a
# stream and use the direction of the prevailing and secondary winds to 
# calculate a Wind Exposure class for each section of major angles along 
# the stream.
# ---------------------------------------------------------------------------
'''
# Import arcpy module (14)
import arcpy as arcpy, datetime
import os

arcpy.env.overwriteOutput = True
arcpy.env.workspace = 'in_memory'

startTime = datetime.datetime.now()
arcpy.AddMessage ('Start processing at :')
arcpy.AddMessage (startTime.strftime('%Y-%m-%d %H:%M'))
 
# Get Parameters from user
workspace = arcpy.GetParameterAsText(0)
windP = arcpy.GetParameterAsText(1)
windS = arcpy.GetParameterAsText(2)

# Current workspace
aprx = arcpy.mp.ArcGISProject('CURRENT')
m = aprx.activeMap

# Get Selected stream info
lyrs = m.listLayers()

for lyr in lyrs:
    if lyr.getSelectionSet():
       sel_lyr = lyr.dataSource
       field = 'GNIS_Name'
       rows = arcpy.da.SearchCursor(lyr,field)
       for row in rows:
            # get name of selected stream
            Stream_Pre = row[0]
            # replaces spaces with underscore
            Stream_Name = Stream_Pre.replace(' ','_')

# Local variables:
stream = os.path.join(str(workspace),Stream_Name)

# Main Body of Script

arcpy.cartography.SimplifyLine(sel_lyr, stream, 'POINT_REMOVE', '45 Meters', 
                               'RESOLVE_ERRORS', 'NO_KEEP', 'CHECK', '')

arcpy.management.SplitLine(stream,stream + '_Split')

# Buffer the stream(Right)

arcpy.Buffer_analysis(stream + '_Split' , stream + '_Buff', '63 Feet', 'RIGHT'
                      , 'FLAT', 'NONE', '', 'PLANAR')

# Add Field named Angle

arcpy.AddField_management(stream + '_Buff', 'Angle', 'LONG', '', '', '', '', 
                          'NULLABLE', 'NON_REQUIRED', '')

# Process: Calculate Polygon Main Angle (R)

arcpy.CalculatePolygonMainAngle_cartography(stream + '_Buff', 'Angle', 
                                            'GEOGRAPHIC')

# Process: Add Field (Wind)

arcpy.AddField_management(stream + '_Buff', 'wind', 'LONG', '', '', '20', '', 
                          'NULLABLE', 'REQUIRED', '')

arcpy.CalculateField_management(stream + '_Buff', 'wind', windP)

# Process: Calculate Field (Adjust Angle R)
expression1 = 'getClass((!Angle!)+ !wind!)'

codeblock1 = '''
def getClass(n):
    if n < 0:
        return n * -1
    else:   
        return n'''

arcpy.CalculateField_management(stream + '_Buff', 'wind', expression1, 
                                'PYTHON3', codeblock1)

# Process: Add Field (Wind2_R)
arcpy.AddField_management(stream + '_Buff', 'wind2', 'LONG', '', '', '20', '', 
                          'NULLABLE', 'NON_REQUIRED', '')
 
arcpy.CalculateField_management(stream + '_Buff', 'wind2', windS)

# Process: Calculate Field (Adjust Secondary Angle R)
expression2 = 'getClass((!Angle!)+ !wind2!)'

arcpy.CalculateField_management(stream + '_Buff', 'wind2', expression2, 
                                'PYTHON3', codeblock1)

# Process: Add Field (Index_R)
arcpy.AddField_management(stream + '_Buff', 'Index', 'LONG', '', '', '20', '', 
                          'NULLABLE', 'REQUIRED', '')

# Process: Calculate Field (Index R)
expressionReclass = "Reclass(!wind!)"
codeblock_wind ='''def Reclass(wind):
	if (wind >= 0 and wind <= 20):
		return 5
	elif (wind > 20 and wind <= 70):
		return 4
	elif (wind > 70 and wind <= 110):
		return 3
	elif (wind > 110 and wind <=160):
		return 2
	elif(wind > 160 and wind <=200):
		return 1
	elif(wind > 200 and wind <=250):
		return 2
	elif(wind > 250 and wind <=290):
		return 3
	elif(wind > 290 and wind <=340):
		return 4
	elif(wind > 340):
		return 5'''

arcpy.CalculateField_management(stream + '_Buff', 'Index', expressionReclass, 
                                'PYTHON_9.3', codeblock_wind)

# Process: Add Field (Index2_R)
arcpy.AddField_management(stream + '_Buff', 'Index2', 'LONG', '', '', '20', '',
                          'NULLABLE', 'NON_REQUIRED', '')

# Process: Calculate Field (Index2 R)
expressionReclass2 = 'Reclass(!wind2!)'
codeblock_wind2 = '''def Reclass(wind2):
	if (wind2 >= 0 and wind2 <= 20):
		return 5
	elif (wind2 > 20 and wind2 <= 70):
         	return 4
	elif (wind2 > 70 and wind2 <= 110):
	    	return 3
	elif (wind2 > 110 and wind2 <=160):
	    	return 2
	elif(wind2 > 160 and wind2 <=200):
	    	return 1
	elif(wind2 > 200 and wind2 <=250):
	    	return 2
	elif(wind2 > 250 and wind2 <=290):
	    	return 3
	elif(wind2 > 290 and wind2 <=340):
	    	return 4
	elif(wind2 > 340):
	    	return 5'''       
arcpy.CalculateField_management(stream + '_Buff', 'Index', expressionReclass2, 
                                'PYTHON_9.3', codeblock_wind2)
        
# Process: Add Field (Sum_R)
arcpy.AddField_management(stream + '_Buff', 'SumOfRanks', 'SHORT', '', '', 
                          '20', '', 'NULLABLE', 'NON_REQUIRED', '')

# Process: Calculate Field (Add Index R)
arcpy.CalculateField_management(stream + '_Buff', 'Index', '!Index!+ !Index2!',
                                'PYTHON_9.3', '')

# Process: Add Field (Class_R)
arcpy.AddField_management(stream + '_Buff', 'Class', 'SHORT', '', '', '20', '',
                          'NULLABLE', 'NON_REQUIRED', '')

# Process: Calculate Field (Class R)
codeblock3 = '''
def Reclass(SumOfRanks):
	if (SumOfRanks >= 0 and SumOfRanks <= 1):
		return 1
	elif (SumOfRanks > 1 and SumOfRanks <= 4):
		return 2
	elif (SumOfRanks > 4 and SumOfRanks <= 6):
		return 3
	elif (SumOfRanks > 6 and SumOfRanks <= 8):
		return 4
	elif (SumOfRanks > 8 and SumOfRanks <= 10):
		return 5'''
    
arcpy.CalculateField_management(stream + '_Buff', 'Index', 
                                'Reclass(!SumOfRanks!)', 'PYTHON_9.3'
                                ,codeblock3)

# add new layer and delete extra layers
m.addDataFromPath (stream + '_Buff')

#arcpy.DeleteFeatures_management (stream)
#arcpy.DeleteFeatures_management (stream + '_Split')

endTime = datetime.datetime.now()
arcpy.AddMessage ('Finished processing at :')
arcpy.AddMessage (endTime.strftime('%Y-%m-%d %H:%M'))
arcpy.AddMessage ('Process duration:')
arcpy.AddMessage (endTime - startTime)‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

Re: In ArcMap Pro, how to get data from a selected layer

RandyBurton — Thu, 16 May 2019 21:08:03 GMT

You might try adding the following line just after CalculateField - at line 141. GetMessages will return messages from the CalculateField tool (i.e., the tool last used) and you can see if it ran successfully.

arcpy.AddMessage(arcpy.GetMessages())‍

Re: In ArcMap Pro, how to get data from a selected layer

jasongraham — Thu, 16 May 2019 21:21:43 GMT

Thanks, it didnt give my any despite running the whole script. I will try another method.

Re: In ArcMap Pro, how to get data from a selected layer

jasongraham — Sat, 11 Dec 2021 06:06:36 GMT

For what is worth, I have tried all three methods. They all run without error but do not fill in the index field and does not report any errors.

Method 1
index = ['Index']
rows = arcpy.UpdateCursor(fc, index)
for row in rows:
    if (row.wind >= 0 and row.wind <= 20):
        index = 5
    elif (row.wind > 20 and row.wind <= 70):
        index = 4
    elif (row.wind > 70 and row.wind <= 110):
        index = 3
    elif (row.wind > 110 and row.wind <=160):
        index = 2
    elif(row.wind > 160 and row.wind <=200):
        index = 1
    elif(row.wind > 200 and row.wind <=250):
        index = 2
    elif(row.wind > 250 and row.wind <=290):
        index = 3
    elif(row.wind > 290 and row.wind <=340):
        index = 4
    elif(row.wind > 340):
        index = 5
    rows.updateRow(row)   
del row
del rows    
    
method 2
fields = ['Index', 'wind']
with arcpy.da.UpdateCursor(fc,fields) as cursor:
    for row in cursor:
        #wind = row[1]
        #Index = row[0]

        if (row[1] >= 0 and row[1] <= 20):
            row[0] = 5
        elif (row[1] > 20 and row[1] <= 70):
            row[0] = 4
        elif (row[1] > 70 and row[1] <= 110):
            row[0] = 3
        elif (row[1] > 110 and row[1] <=160):
            row[0] = 2
        elif(row[1] > 160 and row[1] <=200):
            row[0] = 1
        elif(row[1] > 200 and row[1] <=250):
            row[0] = 2
        elif(row[1] > 250 and row[1] <=290):
            row[0] = 3
        elif(row[1] > 290 and row[1] <=340):
            row[0] = 4
        elif(row[1] > 340):
            row[0] = 5
    
        cursor.updateRow(row)'''
        
arcpy.AddMessage(arcpy.GetMessages())

method 3        
expressionReclass = "Reclass(!wind!)"
codeblock_wind ='''def Reclass(wind):
	if (wind >= 0 and wind <= 20):
		return 5
	elif (wind > 20 and wind <= 70):
		return 4
	elif (wind > 70 and wind <= 110):
		return 3
	elif (wind > 110 and wind <=160):
		return 2
	elif(wind > 160 and wind <=200):
		return 1
	elif(wind > 200 and wind <=250):
		return 2
	elif(wind > 250 and wind <=290):
		return 3
	elif(wind > 290 and wind <=340):
		return 4
	elif(wind > 340):
		return 5'''   
#cursor = arcpy.UpdateCursor(sel_lyr,'Index')

arcpy.CalculateField_management(stream + '_Buff', 'Index', expressionReclass, 
                                'PYTHON_9.3', codeblock_wind)‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

Re: In ArcMap Pro, how to get data from a selected layer

JoshuaBixby — Sat, 18 May 2019 14:46:25 GMT

Have you tried hard coding the parameters and then loading the script in the interactive Python window. If it works there, then you know it has to do with running the script as a tool.

Re: In ArcMap Pro, how to get data from a selected layer

jasongraham — Sat, 18 May 2019 20:07:08 GMT

Yes, they all work. I did an addmessage be for and after the function. Before index is 0 and after it has a number but it does not seem to write to the table.

Re: In ArcMap Pro, how to get data from a selected layer

JoshuaBixby — Sat, 18 May 2019 23:00:00 GMT

I am a bit confused. I asked if you have run it in the interactive Python window. Your response, "yes, they all work." But, then you state "it does not seem to write to the table." I will rephrase my question. Do you get the exact same results if you run the script as a script tool vs running it in the interactive Python window?

Re: In ArcMap Pro, how to get data from a selected layer

jasongraham — Sun, 19 May 2019 11:42:14 GMT

Sorry, I will try to clarify.

In the version I used codeblocks, (method 3) I tested the code in the field calculator and that was successful.

In method two above I used addmessage to see the results in each stage and the output seems correct but no change in the feature class table.

The code at this point can not be test on the interactive withndow as it requires to get parameters from users. If I put temp values in, it works fine. Off for holiday, get back to it later. Thanks

Re: In ArcMap Pro, how to get data from a selected layer

JoshuaBixby — Sun, 19 May 2019 14:07:13 GMT

If I put temp values in, it works fine.

If you put temp values in and run it from the interactive Python window, as a script tool, or both?

Re: In ArcMap Pro, how to get data from a selected layer

jasongraham — Wed, 29 May 2019 22:35:35 GMT

as a script tool

Re: In ArcMap Pro, how to get data from a selected layer

jasongraham — Sat, 11 Dec 2021 06:06:39 GMT

When I use this to update a field:

fields = ['Index', 'wind']
arcpy.AddMessage(fc)

with arcpy.da.UpdateCursor(fc,fields) as cursor:
    for row in cursor:
        #wind = row[1]
        #Index = row[0]
        arcpy.AddMessage(row)
        if (row[1] >= 0 and row[1] <= 20):
            row[0] = 5
        elif (row[1] > 20 and row[1] <= 70):
            row[0] = 4
        elif (row[1] > 70 and row[1] <= 110):
            row[0] = 3
        elif (row[1] > 110 and row[1] <=160):
            row[0] = 2
        elif(row[1] > 160 and row[1] <=200):
            row[0] = 1
        elif(row[1] > 200 and row[1] <=250):
            row[0] = 2
        elif(row[1] > 250 and row[1] <=290):
            row[0] = 3
        elif(row[1] > 290 and row[1] <=340):
            row[0] = 4
        elif(row[1] > 340):
            row[0] = 5

        cursor.updateRow(row)
        arcpy.AddMessage(row)‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

and check the messages I get

[None, 101]
[3, 101]
[None, 56]
[4, 56]
[None, 24]
[4, 24]
[None, 47]
[4, 47]
showing that Index has nothing and wind has data which is right

then the next add message has data in both.

However the actual table never gets updated but the tool completes without error.