Improve compatability with the set_output API from scikit-learn

[paucablop]

Description

All the transformers from chemotools are compatible with scikit-learn, that is the objective of chemotools 👍. In one of the most recent releases of scikit-learn they have introduced the set_output API, which basically allows the user to define an pandas as output. This will produce a pandas.DataFrame object as output instead of the default numpy.ndarray. This works fine with most of chemotools transformers, but I have some specific issues:

👉 The column names are lost after the transformation

When I use a chemotools transformer setup to produce a pandas.DataFrame, it does not keep the column names, and produces an output without column names. I have compared the functionality with other scikit-learn transformers (such as StandardScaler(), and I have seen that they do keep the column names in the output.

👉 The API does not work when the transformer reduces the number of features

Some transformers will reduce the number of features on our dataset (e.g., will select a subset of columns from it). These are under the variable selection transformers. I don't really know how to fix this issue.

Hacktoberfest Challenge

We invite open source developers to contribute to our project during Hacktoberfest. The goal is to improve compatibility with the set_output API

How to Contribute

Here is the contributing guidelines

Contact

[We can have the the conversation in the Issue or the Discussion](#45)

Resources

👉 Link to set_output API form scikit-learn

👉Link to problem description