keras: how to save the training history attribute of the history object

What I use is the following:

    with open('/trainHistoryDict', 'wb') as file_pi:
        pickle.dump(history.history, file_pi)

In this way I save the history as a dictionary in case I want to plot the loss or accuracy later on.

Another way to do this:

As history.history is a dict, you can convert it as well to a pandas DataFrame object, which can then be saved to suit your needs.

Step by step:

import pandas as pd

# assuming you stored your model.fit results in a 'history' variable:
history = model.fit(x_train, y_train, epochs=10)

# convert the history.history dict to a pandas DataFrame:     
hist_df = pd.DataFrame(history.history) 

# save to json:  
hist_json_file = 'history.json' 
with open(hist_json_file, mode='w') as f:
    hist_df.to_json(f)

# or save to csv: 
hist_csv_file = 'history.csv'
with open(hist_csv_file, mode='w') as f:
    hist_df.to_csv(f)