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Moving values within FC works, but not for a List of FCs

GabrielBacca-Cortes

Hi Everyone -

I have a code that moves values around within a FC [which is the result of an intersection] from one field to another so that I will have them all previously intersected values aligned in one single row. The code works well when I apply it to one FC at a time, but when I extend it to a List of FCs, it does not work. I've tried fixing it by playing with the indentation of the UpdateCursor lines, but it didn't work. Any idea what might be happening/missing ?

On another token, it seems to me that what I am trying to do, it could be done a lot simpler, any ideas on how to optimize it ?

Thanks much !

Gabriel

import arcpy, os

from arcpy import env

# Set environment settings

env.workspace = r"C:\GIS\Track1\1_Orig\int2"

# Set local variables

copyFields = ("PorousMed","K_1","Pity_1","Leng_m")

insertFd1 = ['PM1','K1','P1','leng_m1']

insertFd2 = ['PM2','K2','P2','leng_m2']

insertFd3 = ['PM3','K3','P3','leng_m3']

insertFd4 = ['PM4','K4','P4','leng_m4']

insertFd5 = ['PM5','K5','P5','leng_m5']

valueList = []

try:

fcList = arcpy.ListFeatureClasses("","POLYLINE")

for fc in fcList:

print fc

rows = arcpy.da.SearchCursor(fc, copyFields)

for row in rows:

valueList.append(row[0])

valueList.append(row[1])

valueList.append(row[2])

valueList.append(row[3])

cursor = arcpy.UpdateCursor(fc, insertFd1)

for row in cursor:

row.setValue("PM1",valueList[0])

row.setValue("K1",valueList[1])

row.setValue("poros1",valueList[2])

row.setValue("leng_m1",valueList[3])

cursor.updateRow(row)

del cursor, row

cursor = arcpy.UpdateCursor(fc, insertFd2)

for row in cursor:

row.setValue("PM2",valueList[4])

row.setValue("K2",valueList[5])

row.setValue("poros2",valueList[6])

row.setValue("leng_m2",valueList[7])

cursor.updateRow(row)

del cursor, row

cursor = arcpy.UpdateCursor(fc, insertFd3)

for row in cursor:

row.setValue("PM3",valueList[8])

row.setValue("K3",valueList[9])

row.setValue("poros3",valueList[10])

row.setValue("leng_m3",valueList[11])

cursor.updateRow(row)

del cursor, row

cursor = arcpy.UpdateCursor(fc, insertFd4)

for row in cursor:

row.setValue("PM4",valueList[12])

row.setValue("K4",valueList[13])

row.setValue("poros4",valueList[14])

row.setValue("leng_m4",valueList[15])

cursor.updateRow(row)

del cursor, row

cursor = arcpy.UpdateCursor(fc, insertFd5)

for row in cursor:

row.setValue("PM5",valueList[16])

row.setValue("K5",valueList[17])

row.setValue("poros5",valueList[18])

row.setValue("leng_m5",valueList[19])

cursor.updateRow(row)

del cursor, row

except:

print arcpy.GetMessages(0)

print arcpy.GetMessages(1)

print arcpy.GetMessages(2)

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Accepted answers

XanderBakker

This code seems to get the result (assuming that I understand it now):

import arcpy, os
import sys
import traceback
from arcpy import env

# Set environment settings
# env.workspace = r"C:\GIS\Track1\1_Orig\int2"
env.workspace = r"C:\Forum\updateCursorsAtts\testdata"

# Set local variables
dct_flds = {'PorousMed': ['PM1','PM2','PM3','PM4','PM5'],
            'Kcond_1': ['Kcond1','Kcond2','Kcond3','Kcond4','Kcond5'],
            'Porosity_1': ['Poros1','Poros2','Poros3','Poros4','Poros5'],
            'Leng_m': ['leng_m1','leng_m2','leng_m3','leng_m4','leng_m5']}

# changed fieldnames corresponding to the data
# PorousMed: Text
# K_1= Kcond_1: Double
# Pity_1=Porosity_1: Double
# Leng_m: Double
def_tuple = ("",0,0,0)

# create list of fields from dictionary (contains all fields: input and output)
flds = []
for k, lst in dct_flds.items():
    flds.append(k)
    for fld in lst:
        flds.append(fld)

flds_in = dct_flds.keys()

try:
    fcList = arcpy.ListFeatureClasses("","POLYLINE")
    print fcList
    for fc in fcList:
        print fc
        # create the list from the input fields
        valueList = []
        with arcpy.da.SearchCursor(fc, flds_in) as curs:
            for row in curs:
                valueList.append(list(row))

        # correct for less than 5 elements
        while len(valueList) <= 5:
            valueList.append(def_tuple)

        with arcpy.da.UpdateCursor(fc, flds) as curs:
            for row in curs:
                for fld_in, lst_out in dct_flds.items():
                    # val_in = row[flds.index(fld_in)]
                    for fld_out in lst_out:
                        num = int(fld_out[-1:])
                        lst_vals = list(valueList[num])
                        row[flds.index(fld_out)] = lst_vals[flds_in.index(fld_in)]
                curs.updateRow(row)

except Exception as e:
    print e
    tb = sys.exc_info()[2]
    tbinfo = traceback.format_tb(tb)[0]
    pymsg = "PYTHON ERRORS:\nTraceback info:\n" + tbinfo + "\nError Info:\n" + str(sys.exc_info()[1])
    msgs = "ArcPy ERRORS:\n" + arcpy.GetMessages(2) + "\n"
    print pymsg + "\n"
    print msgs

I'll attach the updated dataset for you to check the result.

Kind regards, Xander

send.zip

All comments

JoshuaBixby

At first glance, you seem to be mixing older/original cursors and the newer data access (arcpy.da) cursors. Your syntax for the update cursors seems wrong. The arcpy.da.UpdateCursor syntax is (in_table, field_names, {where_clause}, {spatial_reference}, {explode_to_points}, {sql_clause}) whereas the arcpy.UpdateCursor syntax is (dataset, {where_clause}, {spatial_reference}, {fields}, {sort_fields}). You appear to be passing your field list as a where clause to your update cursors.

Overall, I recommend switching to using all arcpy.da cursors.

GabrielBacca-Cortes

Thanks Joshua for your response. I tried what you suggested but didn't solve my main problem which is the iteration of this procedure through the other FCs. Actually, when I switched everything back to the newer data access version, it didn't work at all not even for the first FC. I know it is not ideal having cursors with DA and without it, but it gives me the result I want, only that it can be replicated with the list of FCs.

thanks again,

Gabriel

SuryaKant

Hi Gabriel,
I tried to understand your script but it it very confusing(please don't mind). Could you explain your work process(details are important). What are your inputs and what would be your expected result.
This will help me to write a script for you.
Surya

XanderBakker

Yeah, some explanation on the general idea would be helpful. From what I see in your code it doesn’t make much sense:

Your create a list of polyline featureclasses in you workspace
You loop through the featureclasses
- for each feature in the current featureclass you append the values of the input fields to a list
- next you create an update cursor on the same featureclass and start to set the values of the output fields. When doing this you assign the first 4 values of the list (not the additional values appended to the list).

Please note that for the second feature in the featureclass (da.searchcursor) you add the values to the list, but the values from the 1st feature will still be assigned. I don’t think that is what you want to achieve, right?

Since this is all happing in the same featureclass, you could use a single da.UpdateCursor to do this (assuming that you want to assign the value from each feature input field to the output fields of the same feature. That does make sense, although I don’t see why you would want to duplicate those values 5 times in your featureclass...

GabrielBacca-Cortes

Hi Xander and Surya: Thanks for your response.

The two bullets in which Xander summarized part of my code are correct. I am sorry I should have provided a better explanation on my first post. The list of values I am creating is a 5rx4c table that I can index out as follows, so that I can move values to different fields within the same FC as:

[ 0 1 2 3 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19

4 5 6 7 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19

8 9 10 11 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19

12 13 14 15 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19

16 17 18 19] 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19

The values in the original file, in vertical order in the input fields, are the result of intersecting a polyline against polygons, but the main goal of this code is to have a one single part polyline that includes all the information from the intersection. I need to do this for thousands of intersected polylines {FCs} and then append them all out, but that's not in the code I posted. In order to get a one single part polyline I will dissolve the FC for the output fields.

So, yes, the valueList will have to be re-created for each FC, to re-distribute the proper values within it as indicated above.

The code, as it is, does the job for the first FC but it stalls and does not move on to the next FC.

Let me know if you have further questions. Thanks a bunch for comments !

Gabriel

JoshuaBixby

By stall out, what exactly do you mean? Does it stop running and hang? Does it complete but not update what you expect? Does it stop running and generate an error?

GabrielBacca-Cortes

Joshua - by stall out I mean that it does not move to the next FC and locks the modified file, that is the first FC, without generating an error,

regards,

Gabriel

JoshuaBixby

Regarding your use of the older/original UpdateCursor, you are using incorrect syntax. You are getting lucky, if one wants to call it that, because there is a bug in the UpdateCursor where passing a Python list instead of a text-based where_clause causes the where_clause to be ignored. In effect, using cursor = arcpy.UpdateCursor(fc) generates the same cursor for you.

The fact that switching everything to the Data Access cursors meant the code didn't work at all, not even the first FC, is telling you something is wrong with the code even for the first FC. What exactly happened when you use arcpy.da UpdateCursors? Does it run and nothing happens? An error code is generated?

XanderBakker

Sorry Gabriel, it is still unclear what you mean exactly, but if I have to rewrite what your original code was trying to do, then it would be something like this.

import arcpy, os
from arcpy import env

# Set environment settings
env.workspace = r"C:\GIS\Track1\1_Orig\int2"

# Set local variables
dct_flds = {'PorousMed': ['PM1','PM2','PM3','PM4','PM5'],
            'K_1': ['K1','K2','K3','K4','K5'],
            'Pity_1': ['P1','P2','P3','P4','P5'],
            'Leng_m': ['leng_m1','leng_m2','leng_m3','leng_m4','leng_m5']}

# create list of fields from dictionary (contains all fields: input and output)
flds = []
for k, lst in dct_flds.items():
    flds.append(k)
    for fld in lst:
        flds.append(fld)

try:
    fcList = arcpy.ListFeatureClasses("","POLYLINE")
    for fc in fcList:
        print fc
        with arcpy.da.UpdateCursor(fc, flds) as curs:
            for row in rows:
                for fld_in, lst_out in dct_flds.items():
                    val_in = row[flds.index(fld_in)]
                    for fld_out in lst_out:
                        row[flds.index(fld_out)] = val_in
                curs.updateRow(row)

except:
    print arcpy.GetMessages(0)
    print arcpy.GetMessages(1)
    print arcpy.GetMessages(2)

GabrielBacca-Cortes

Thanks Xander - I ran the script you sent, but didn't run. The [flds] list looks very different from what I need. So I am hoping that by adding the fields on top here, it is clearer how the code should deliver the results I want.

PM PM1 PM2 pm5

K_1 K1 K2 k5

Pit_1 P1 P2 p5

LenM Lm1 Lm2 lm5

[ 0 1 2 3 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19

4 5 6 7 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19

8 9 10 11 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19

12 13 14 15 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19

16 17 18 19] 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19

After dissolving I will be getting:

PM1 PM2 pm5

K1 K2 k5

P1 P2 p5

Lm1 Lm2 lm5

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19

SusanJones

I had exactly this last week with using the arcpy.da.InsertCursor and arcpy.da.SearchCursor.

Seems that can only use one cursor at a time.

In the end I pulled all my search records into an array and used them as part of my insert/update records.

Took a bit of getting my head around, but got there in the end.

Here is my logic:

#todo: process Layer

print "\nProcess CAFS Layer"

#todo: search Data

recs = arcpy.da.SearchCursor(in_table = "EMU_VIEW", field_names = ["VehicleId", "Timestamp", "Longitude", "Latitude"])

rows = []

for rec in recs:

pt = [rec[2], rec[3]]

row = [pt, rec[1], rec[0], "CAFS", rec[1], rec[2], rec[3]]

rows.append(row)

del recs

#todo: insert Data

print "insert Data"

fldList = ["SHAPE@XY", "DateTime", "VehicleID", "FeedType", "Timestamp", "Longitude", "Latitude"]

irecs = arcpy.da.InsertCursor(in_table = fc, field_names = fldList)

for row in rows:

irecs.insertRow(row)

del irecs

Susan

JoshuaBixby

I wouldn't go as far as saying you can only use one cursor at a time. There are several factors that affect how and whether multiple cursors will work together on a data set. The types of locks that the cursors require are one factor. The order of which cursors are opened first can be a factor. The backend data storage format is another factor. When it comes to using multiple cursors to access spatial data, having the data in an enterprise DBMS makes a big difference.

SusanJones

Totally agree - storage format is part of it. For tis particular task I have been using File Geodatbase

GabrielBacca-Cortes

thanks Susan for your response. The problems are somewhat different as in your code all the values within each field are taken from one FC and inserted into the fields of another FC, but I modified my code based on that Search-Insert Cursor logic and this is what I got: [let me remind you that in my case each line from the array/valueList goes into a different set of fields, so that I indexed 'valueList' for as many 'lines' or number of inserts I have]

# Import system modules

import arcpy, os

from arcpy import env

# Set environment settings

env.workspace = r"C:\GIS\Track1\1_Orig\Track_int2"

# Set local variables

copyFields = ("PorousMed","Kcond_1","Porosity_1","Leng_m")

insertFd1 = ['PM1','Kcond1','Poros1','leng_m1']

insertFd2 = ['PM2','Kcond2','Poros2','leng_m2']

insertFd3 = ['PM3','Kcond3','Poros3','leng_m3']

insertFd4 = ['PM4','Kcond4','Poros4','leng_m4']

insertFd5 = ['PM5','Kcond5','Poros5','leng_m5']

try:

fcList = arcpy.ListFeatureClasses("","POLYLINE")

for fc in fcList:

print fc

vals = arcpy.da.SearchCursor(fc, copyFields)

valueList = []

for row in vals:

line = [vals[0],vals[1],vals[2],vals[3]]

valueList.append(line)

del vals

cursor = arcpy.da.InsertCursor(fc, insertFd1)

for row in rows:

cursor.insertRow(valueList[0])

del cursor

cursor = arcpy.da.InsertCursor(fc, insertFd2)

for row in rows:

cursor.insertRow(valueList[1])

del cursor

cursor = arcpy.da.InsertCursor(fc, insertFd3)

for row in rows:

cursor.insertRow(valueList[2])

del cursor

cursor = arcpy.da.InsertCursor(fc, insertFd4)

for row in rows:

cursor.insertRow(valueList[3])

del cursor

cursor = arcpy.da.InsertCursor(fc, insertFd5)

for row in rows:

cursor.insertRow(valueList[4])

del cursor

except:

print arcpy.GetMessages(0)

print arcpy.GetMessages(1)

print arcpy.GetMessages(2)

Unfortunately, this didn't work. I think the partitioning within each indexed 'valueList' among the respective fields didn't happen. any thoughts ?

thanks !

XanderBakker

I just posted the code and attached the result using your shapefiles. Let me know if it is what you were looking for.

GabrielBacca-Cortes

Thanks Xander - yes, it does work. Only that through 'valueList', the code moves the second set of values [1] instead of the first set [0] from 'flds_in' to PM1-K1-P1-lengm1. I've been trying to fix this, but honestly I am having difficulties understanding the code enough to modify it, 🙂

For the first FC 'xy_1.shp', I'd like to move to PM1-Kcond1-Poros1-Lengm1, the first row of values from 'flds_in':

['Gravelly silt', 0.25, 4.2924, 0.41] not the second row: ['Silty Sand', 10.5, 11.2832, 0.36].

Also, and this is my lack of understanding of the code, but when I print 'valueList', running the code only for the first FC in order to see what the code does more clearly, it prints:

[[u'Silty Sand', 10.5, 8.9952, 0.36], [u'Medium Sand', 85.2, 12.1677, 0.35]]

in which the terms for the third field [Leng_m#] are wrong but they are correct when the code runs and its entirety and delivers the final result:

[['Silty Sand', 10.5, 11.2832, 0.36], ['Medium Sand', 85.2, 5.9327, 0.35]]

Thanks again !

Gabriel

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