[solved] Create bitmask based on changes in a column

KNIME Analytics Platform
#1

Hi,

I have a column with the content [1,1,1,4,4,5,5,5]. I want to know in which rows the changes occur from one row to the next one. I marked the ones bold: [1,1,1,4,4,5,5,5] in other words, I want something like [1,0,0,1,0,1,0,0].

I see the following possibilities but do not know to to use KNIME:

  1. Loop through the column and compare the previous row with the current row in a JavaSnippet, create a new row ant write 1 oder 0. But in the Java-Snippet, I can only access complete column...
  2. Take  the column, create a copy, add an item in the first row of the copy and a last only on the original. Then substract both columns and I get non-zeros values at the rows with the change. But in KNIME I cannot add a cell to only one column.

Can you please help me with my problem?

spider

#2

Hi spider,

please find attached a workflow that hopefully solves your problem. Don't hesitate to ask if anything is unclear with the workflow or it doesn't help.

Best,

Martin

#3

Hi hornm,

thanks very much. You used my 2nd idea and used the "Lag column" node in KNIME to add an additional row. I haven't known this node.

I modified your KNIME workflow to use fewer nodes and attached it.

Kind regards from spider