Integration using MNN tutorial

Hi everyone,

I am working on data integration of 10 single cell samples together using MNNcorrect in scanpy.
I found this tutorial, and I have a lot of questions. (link to the tutorial : scanpy_03_integration)

It runs fine, but I am not understanding why certain steps are done :

  1. adata.raw = adata : this for me means that, whatever has been performed (e.g : scaling normalization) on adata object, whatever was in adata.raw wil be replaced by adata, isn’t it ?
  2. adata2 = adata.rawtoadata() : What is this function suposed to do other than creating an object named adata2, from object adata ? Which here, will consist of assigning adata to the new variable adata2…
  3. Finaly, I do not understand the part where we check if data is normalized ? How is this supposed to help with knowing if the data is normalized or not.

Found this tutorial very helpful and it works fine, but certain parts of it are unclear.
If anyone could help me with this I would be very grateful,

Thanks in advance,