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

• PolyGeo: Please focus your question on the particular software you wish to ask about. You have a tag for ArcGIS Desktop and the only answer so far uses that software. You also mention FME Desktop and Python in your question body and title. I recommend you edit your question to focus it on ArcGIS Desktop so that the first answer is not stranded, and it can be re-opened. You can always ask about the other software in separate questions.

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()])

• Dan Iseminger: With FME use an AttributeTrimmer to remove any last ',' then a StringReplacer to replace ' ,' with nothing.
• gisgis: @user2856 thanks a lot it works just perfect, but how could I integrate these lines of code in PythonCaller in FME ?
• user2856: @gisgis I don't use FME. Do you want me to delete my answer?
• gisgis: no i found it helpful. It worked, but somehow my question it is closed and need to be reviewed for whatsoever reason that i dont understand. But again thanks a lot it worked in my case and I checked your answer as accepted answer.