topic Re: Cursor if/then statements in Python Questions

Cursor if/then statements

QuangTruong — Sun, 12 Dec 2021 01:33:26 GMT

Hi, I am trying to search through a dataset to find a certain value in a certain field in order to update another field in that same row, but I can't quite seem to make the code snippet work. Can somebody tell me what I'm doing wrong? The below code completes just fine but returns nothing.

import arcpy

arcpy.env.workspace = r"C:\Users\paperspace\Google Drive\QTA\19010_PDX Zoning\PDXZoning\PDX_Kerns.gdb"

fieldNames = ['TLID', 'RNO']
tlidList = arcpy.da.SearchCursor("taxlots_Kerns", fieldNames)

for tlids in tlidList:
    string = "*-STR*"
    if tlids[1] == string:
        print(tlids)

I can't tell if I'm using the wildcard incorrectly, the comparison incorrectly, or if there's something else I'm doing wrong. Thanks,

Re: Cursor if/then statements

DanPatterson_Retired — Sun, 12 Dec 2021 01:33:28 GMT

Strings are iterables, so you can look for substrings in strings

s = "-STR"

tlids = [ "abc", "-str", "A_STR", "a_-STR"]

[s in i for i in tlids]

[False, False, False, True]‍‍‍‍‍‍‍

Re: Cursor if/then statements

BlakeTerhune — Sun, 12 Dec 2021 01:33:31 GMT

Applying this logic to your code would be something like this.

import arcpy

arcpy.env.workspace = r"C:\Users\paperspace\Google Drive\QTA\19010_PDX Zoning\PDXZoning\PDX_Kerns.gdb"

fieldNames = ['TLID', 'RNO']
find_string = "-STR"
with arcpy.da.SearchCursor("taxlots_Kerns", fieldNames) as tlidList:
    for tlid, rno in tlidList:
        if find_string in tlid:
            print(tlid)‍‍‍‍‍‍‍‍‍‍

Re: Cursor if/then statements

JoshuaBixby — Sun, 12 Dec 2021 01:33:34 GMT

If you want to update rows, you should use an update cursor instead of a search cursor. Instead of doing the string search in Python, you can also put a SQL WHERE clause when you set up the cursor:

import arcpy

arcpy.env.workspace = r"C:\Users\paperspace\Google Drive\QTA\19010_PDX Zoning\PDXZoning\PDX_Kerns.gdb"

fieldNames = ['TLID', 'RNO']
tlidList = arcpy.da.SearchCursor("taxlots_Kerns", fieldNames)
sql = "RNO LIKE '%-STR%'"

with arcpy.da.UpdateCursor("taxlots_Kerns", fieldNames, sql) as cur:
    for row in cur:
        row.updateRow()  # update row with new values‍‍‍‍‍‍‍‍‍‍‍