Flow variable for data type in Column Rename node

KNIME Analytics Platform
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How can I pass a flow variable to the Column Rename node to change the data type from datavalue to stringvalue? I’m trying to avoid having manually change it for hundreds of columns.

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The simple way to figure out flow variable is to first configure the node the way you want it.Then go to the Flow Variables tab and define the name for a flow variable for the field you want:
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Run the node, and see what value the Flow Variable takes.
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Create that flow variable and use to control the configuration of the node:
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If you have hundreds of columns, then I’d probably consider using a string($$CURRENTCOLUMN$$) function in the String Manipulation (Multi-Column) node.

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I like to use the Column Expressions node to perform a logic test and flag the columns, then column splitter node to separate them, then a Multi-Column node to apply the changes to all routed columns as described above.

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Thanks for the prompt reply. I tried the String Manipulation node, but can get it to convert the column headers to strings like the manual Column Rename node will. What am I missing? Executing the node with the attached configuration does nothing.

String Manipulation
String Manipulation1271×875 181 KB

5

The screenshot is cut off; how is the rest of node configured?

It would be easiest if you uploaded some data and maybe a workflow so that we can take a look.

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Here’s the workflow with the Column Rename node and a String Manipulation stub. Its my attempt at Just KnimeIt Challenge 17. Its too large to send. Here’s a DropBox link. Thanks for having a look.

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Use the Column Auto Type Cast node first.

If after that you still want strings, then the String Manipulation (Multi Column) node will work…

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Thanks very much! All I needed was the Column Auto Type Cast node. The only reason I was using the String Manipulation node was to feed a manual Column Rename node. Folks like you are great. I’m a 76 year old retiree and relative Knime neophyte. I’m playing with Knime to keep a few brain cells firing.

6 Likes
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:+1: :+1: :+1: :+1: :+1: :+1: :+1: Awesome!

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Though the rename node does allow the change of variable types it can lead to unwanted results

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