Remove empty spaces with FME PythonCaller

Question

I have 4 fields in the attribute table. After I merge these attribute fields in one single attribute field using FME Desktop 2020.1, it empty records within the fields are producing empty spaces and I want to get rid of empty spaces.

what I have:

Attribute field A

1,2,3,4
1, ,3,4
 ,2, ,4
 , , ,4
 , ,3, 
1,2, ,4


What I want:

Attribute field A

1,2,3,4
1,3,4
2,4
3
1,2,4

Answer 1

It would be easier to merge the fields without the additional commas to begin with using a field calculation in ArcGIS Desktop.

• Create "Field_A"

• Open field calculator

• Select Python parser

• Tick "Show Codeblock"

• in the "Pre-Logic Script Code" block define a function:

   def merge_fields(*fields):
       return ', '.join([f for f in fields if f])
  

• in the "Field_A = " block:

   merge_fields(!FIELD_1!, !FIELD_2!, !FIELD_3!, !FIELD_4!)
  

Note: if your data is in shapefile format, ArcGIS uses spaces in text fields to indicate NULLs so you need to handle that by stripping them:

    def merge_fields(*fields):
        return ','.join([f.strip() for f in fields if f.strip()])