Insert columns in a regular intervals


Traying to figure out:
Having data 123456789… in which each number is in a different column,
I want to insert a new column with a comma regularly after 3 values. Like:

Any ideas?



here is an example how i would solve it.

Example.knwf (157.7 KB)



another solution would be a “String Manipulation” Node.

If your DataType is string already:

If your DataType is not a string already, either use a e.g. “Number to String” node before the “String Manipulator” or it should look like this:



Another idea is to Transpose your dataset (if it is not that big :slight_smile: ) and do some Looping
insert_column.knwf (39.0 KB) . That is what KNIME makes fun to work with, multiple ways to find a solution.

gr. Hans


True by any means, there are so many ways in Knime!
“not that big” :rofl: made my day :+1:


You could also use regex (Yeah I know many ways lead to Rome)

I used the column aggregator to concatenate the columns first
for the split I used
and because I had to remove the commas from second and third split I used regex to remove “,” from the start and end of the string.


Just a note to everyone, I’ve not looked at all the proposed solutions, but anything using the join() function will work only if it is guaranteed that all 9 columns have a value, which I don’t know at this point - it’s not confirmed by the requester.

If there are any missing values, Knime will not join with missing values. For example:

Of course, you can always convert missing values to empty string:
toEmpty($$CURRENTCOLUMN$$) via a String Manipulation (Multi Column)

And you are able to then join:

On the other hand, Column Combiner (as well as Column Aggregator used by @Daniel_Weikert) would combine missing values:

May be going with the Column Combiner/Column Aggregator + a regexReplace() to remove all commas except every 3rd one would be the fastest, unfortunately I’m not quite good with regular expression to come up with the proper expression for that.

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Ok, I ended up doing it the other way, that is concatenate the columns with NO separator, which yields 123456789, then adding commas at every 3rd position. I was able to get the proper regex for that:
regexReplace($Concatenate$, ".{3}", "$0,")


Workflow looks like this:

Here’s the workflow:
Insert new column with commas.knwf (8.3 KB)

Note: A lot of the proposed solutions here, including mine, have hardcoded 9 columns, and these solutions work only for 9 columns. Re-reading the requester’s post: “I want to insert a new column with a comma regularly after 3 values” and also notice the three dots (…) in the input data and in the result, these would suggest that 9 columns was just an example. If we have various number of columns, a lot of the suggested solutions would have to be re-configured.

Probably @HansS solution would be the most flexible to configure (change chunk size, which could also be controlled by a variable)


Hi @bruno29a,

Using the regex replace ($Concatenate$, “.{3}”, “$0,”) works super, but you also give me the empty ($$CURRENTCOLUMN$$) for empty columns that were killing me, that was also a question that I was looking for quite some time ;).

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Hi @VAGR_ISK , you can also play around with this flag to include the missing values or not in the Column Aggregator:


Hello there,

nice to see so many different ideas and solutions!

@bruno29a yours is easily generalized with adding another regexReplace() as wrapper function:

regexReplace( regexReplace( $Concatenate$, ".{3}", "$0,"), "(.*),$" , "$0" )



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