Why mixing 'closing prices' of 3 different companies?

[hellojinwoo]

First of all, I would like to thank you for organizing and sharing such a nice repo, Max williams. I would appreciate it if you can answer one small question.

Question

• What is the point of using the .flatten() method in the deep-q-learning-agent.ipynb file in the Example 0? (The screenshot is provided below)

• It mixes the 'closing prices' of 3 different companies (msft, ibm, qcom), so I cannot see why you flattened the train_data, which is (3*3526) numpy.ndarray and plotted it.