How to get val loss and save best checkpoint in the ssd_mobilenet_v1 tutorial

Prerequisites

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1. The entire URL of the documentation with the issue

https://colab.research.google.com/github/google-coral/tutorials/blob/master/retrain_detection_qat_tf1.ipynb#scrollTo=ImucOu0qgMv_

2. Describe the issue

Hi, Im doing transfer learning with the ssd mobilenet v1 and I would like to know how can I get the val loss during the training and how to save only the best checkpoint according to the best val loss. I only get the loss and by default the checkpoints saved are the first one and the last one.

Thank you.

Start with the training and checkpoint sections of retrain_detection_qat_tf1.ipynb at the linked Colab URL, and run the tutorial to confirm what loss values and checkpoint files it currently produces. Done means the tutorial explains how validation loss is obtained and how the best checkpoint is selected and saved.