One to Many "apply"

#1

Hi,

I have a categorical feature to do One Hot Encoding, and I tried using One to Many node. It works fine for training and evaluating, but I couldn’t figure out how to “apply” it to new data.

Let’s say my feature has (on training set) 4 distinct values: A, B, C and D. I use One to Many node to generate 4 columns, then I train a model on it.
My pipeline for new data should perform the same transformation, so I have the same 4 columns to feed my trained model.

But if I use One to Many on new data, let’s say I have a single row of data with value C on my feature. I will be missing columns A, B and D. How can I make sure the corresponding columns are created in order to feed the model?

I am relatively new to KNIME, so maybe I am missing something…

Best,
Daniel

0 Likes

#2

Hi @dvoigtgodoy

When do the one-hot-encoding you can write your “formula” into a PMML. You can reuse the PMML by PMML Transformation Apply node. I created an example wf 1_to_may_pmml.knwf (24.1 KB) . As you see the value “green” is missing in the second table , the PMML Transformation node creates a column “green” but only with values “0”.
pmml
Hope this helps,

gr. Hans

2 Likes

#3

Hi there @dvoigtgodoy,

welcome to KNIME Community Forum!

I guess what @HansS offered will do it but also there are Table Validator and Table Validator (Reference) nodes that can ensure a certain table structure.

Br,
Ivan

1 Like