Yes. I'm assuming you want to use python libraries to process the data, you can use a javascript interpreter such as Brython to run python client side in the browser.

http://www.brython.info

However. I would recon the main part of such a project would be overcomming techincal difficulties getting all the technology working together, rather than coding the features of your app.

A faster solution would be to distribute a non web python application, or upload the file for processing on the server as you outline.

regarding the undo problem, I would simply store copies of the data at the various steps if you are only working on a small sample subset.

Otherwise, there is the command pattern. Store each step as a Command object, remeber the order and which step the user is on, and you can rerun the steps on the data to get to the required step

Yes. I'm assuming you want to use python libraries to process the data, you can use a javascript interpreter such as Brython to run python client side in the browser.

http://www.brython.info

However. I would recon the main part of such a project would be overcomming techincal difficulties getting all the technology working together, rather than coding the features of your app.

A faster solution would be to distribute a non web python application, or upload the file for processing on the server as you outline.

regarding the undo problem, I would simply store copies of the data at the various steps if you are only working on a small sample subset.

Otherwise, there is the command pattern. Store each step as a Command object, remember the order and which step the user is on, and you can rerun the steps on the data to get to the required step