By the way, below there is a call to `self._data = pd.concat(_samples, ignore_index=True)`. Is there a way to get the number of epochs directly from `self._data` at that point (as opposed to storing it separately during the construction of `_samples`)?

As a point of shame, I spent half an hour to an hour yesterday trying to figure it out, reading docs, trying different methods, and was unable to find one :(. This is what frustrates me about Pandas, simple things always seem to become more complicated than they need to be...

I know I can do `self._data.ix[...]` where `...` is in the range of the number of epochs, but I could not find where the number of valid entries in `self._data.ix` was stored (which in this case would be equivalent to the number of epochs).