[GIS] Using replace string function in QGIS Field Calculator

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Within an attribute table I'm trying to replace one string with another using the 'replace' function . As an example, there are a number of features whose field 'NAME' contain the string '(B)' and I'm wanting to replace this with the word 'County'. I'm selecting the 'update existing field' checkbox and using the following expression

 replace( '(B)','(B)','County')

The end result is that the field 'NAME' for every feature is replaced by 'County' irrespective of whether or not the field 'NAME' originally contained the string '(B)'.

Best Answer

replace( '(B)','(B)','County')

tells QGIS to replace the '(B)' in '(B)' with 'Country'.

You want

replace("Name",'(B)','Country')

= replace the '(B)' in "Name" with 'Country'.

Note that the double quotes indicate a field name while the single quotes refer to a static string. These are not interchangeable.

Related Solutions

[GIS] Updating attribute field with random string value

You may create your own custom python function through field calculator function editor to create random strings to populate a field:

Click on the function editor tab within field cal
Create new file and copy in code below

Load the function

from qgis.core import *
from qgis.gui import *
import random, string

@qgsfunction(args='auto', group='Custom')
def myFun(value1, feature, parent):
    return randomword(10)

def randomword(length):
    return ''.join(random.choice(string.lowercase) for i in range(length))

Make a call under expression tab like and click Ok button to run:

myFun("fieldNameToBeUpdated")

Best Answer

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[GIS] Updating attribute field with random string value

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