How do I import and export more than one numpy arrays?

Question

I have four numpy arrays X_train, y_train, X_test, y_test.

I want to know how do I export and import them all together.

I tried exporting them using

numpy.save("data.npy",list, [X_train, y_train, X_test, y_test])

I then tried importing using

np_data = numpy.load("data.npy", allow_pickle=True)

But I can't access the data, and get the following errors:

np_data says array(<class 'list'>, dtype=object)
np_data[0] says IndexError: too many indices for array: array is 0-dimensional, but 1 were indexed

and also I don't understand why allow_pickle is necessary ?

Answer 1

You can simply use numpy.savez to save multiple numpy arrays to a single file. This would look as follows in your case:

numpy.savez("data.npy", X_train=X_train, y_train=y_train, X_test=X_test, y_test=y_test)