If you can work with Python/Julia/R then I would still recommend the IPython notebook, since you will not get anything more interactive and better suited to data analysis and visualization in one package. It basically allows you to run arbitrary snippets of code and interactively work with your data (code, visualize repeat). In general, I would not try to develop your algorithms directly within your app but instead generate some example data, export that data and then work with it in IPython (or another tool) to iteratively build the algorithm. As soon as you have a working solution you can then integrate/translate the code back into your application.