Passing through columns in scikit-learn typically means that those columns are not subjected to any transformations. There are a few ways to do this in scikit-learn.
1. Using ColumnTransformer
One way to pass through columns is to use the passthrough parameter in a ColumnTransformer object. Here’s an example:
In this example, we use the 'passthrough' string for the transformer object in the tuple corresponding to the columns that we want to pass through. We also include a StandardScaler transformer for the other columns. The resulting transformed data will include the original ‘sepal length (cm)’ and ‘sepal width (cm)’ columns.
2. Using FunctionTransformer
Another way to pass through columns is to use a FunctionTransformer object in a Pipeline. Here’s an example:
In this example, we define a Pipeline with a ColumnTransformer object followed by a StandardScaler object. We specify the columns to pass through using the 'passthrough' string, and we specify those columns in the third element of the tuple.