Replace field values with arcpy update cursor

Question

I am a bit new for the arcpy. I have a database table so I can't use field calculator. so I would like to use Python script for solving the issue.

import arcpy
... # Your input feature class
... table = r'D:\werk_map.gdb\test_gw_bsl'
... # Start an update cursor and change values from 0 to 100 in a field called "your_field"
... with arcpy.da.UpdateCursor(table, "Thickness") as cursor:
... for row in cursor:
... if row[0] == "0,1":
... row[0] = "0,5"
... cursor.updateRow(row)

enter image description here

I just want to replace all "0,1" values in the thickness field with "0,5". The above written arcpy script is running without error but not changing the values in the table. I think may be it has do something with the comma in the field value.

• Midavalo: Welcome to GIS SE! Thank you for taking the new user tour.
• GISHuman: After your for statement try: print row[0] to see what is actually being picked up by the cursor

Answer 1

First I don't see why you can't do this using the Field Calculator - it works on Database Tables as well as Feature Classes and Layers.

Now onto your script - you are very close. Your cursor if is checking for "0,1" and wanting to replace with "0,5" - the quote-marks around it means it is looking for text but your values are numbers, stored in a numeric type field. Python won't find text in a numeric field.

Also, because of how python treats commas, you will need to use a decimal point . in your code (it won't affect how it is stored in your table):

import arcpy
 # Your input feature class
 table = r'D:\werk_map.gdb\test_gw_bsl'
 # Start an update cursor and change values from 0 to 100 in a field called "your_field"
 with arcpy.da.UpdateCursor(table, "Thickness") as cursor:
 for row in cursor:
 if row[0] == 0.1:
 row[0] = 0.5
 cursor.updateRow(row)

• Ram: Thank you, Midavalo for you reply. i tried your suggestion but its not working. The field thickness accepts only ", " commas instead of "." decimal points( float nummer). The field calculator is greyed out. I think its a relational database table.
• GISHuman: Just curious as to how you know its a numeric field? I would have thought since it contained a comma that it would have to be text?
• Midavalo: @GISKid The values are right-aligned in the screenshot. Numbers are (usually) right-aligned, text is left-aligned. I could be wrong though, other countries/regions may have the left/right align settings different than what I use
• Ram: yes its a float numeric field
• Ram: yes exactly we use commas instead of decimal points in numeric field