Why was offset used to plot time series in Notebook 10?

[abhi8893]

In model_1 , the time series is plotted as follows:

offset = 300
plt.figure(figsize=(10, 7))
# Account for the test_window offset and index into test_labels to ensure correct plotting
plot_time_series(timesteps=X_test[-len(test_windows):], values=test_labels[:, 0], start=offset, label="Test_data")
plot_time_series(timesteps=X_test[-len(test_windows):], values=model_1_preds, start=offset, format="-", label="model_1_preds")

I don't get where this offset = 300 is coming from?
Thanks!

[mrdbourke]

Hey abhi,

Check the parameters of the plot_time_series() function.

The start parameter is used to start the plot at a certain index (an offset).

# Account for the test_window offset and index into test_labels to ensure correct plotting
plot_time_series(timesteps=X_test[-len(test_windows):], 
    values=test_labels[:, 0], 
    start=offset, # 'offset' variable used here to make the plot start later in the series
    label="Test_data")

Try adjusting the offset parameter and seeing how it changes the plot.

[abhi8893]

Oh, do you mean you set an offset=300 to just focus on newer timesteps? The X_test starts at around 2019 November, so setting an offset of 300 would make it start from 300 timesteps later. Please tell me if I am getting something wrong here?

[mrdbourke]

Yes, what you're saying is correct.