What is the best way to apply the ClassificationInterpretation methods on the training set. For example to plot the confusion matrix, or get the top/bottom losses on the training set. This could be useful for comparing training and validation set results for signs of overfitting, but the main reason I want to use it is to apply the FileDeleter class from lesson 2 to clean up the training set as well. To do that, it seems we need a way to apply the top_losses() method to the training set.
Your best bet is probably to run what is called “cross validation”, in essence you should cycle through all of your data giving each image a chance to be in the validation set. eg if your validation set is 20%, you cut your data into 5 pieces ABCDE. Then you train on ABCD with E as validation, then ABCE with D as validation and so forth. In fastai v1 AFAIK you’d have to read up on creating your own datasets to get this working.