medium_training_validation.py

training_files = []
training_labels = []
validation_files = []
validation_labels = []

for label in range(CLASSES_SIZE):
    indexes = np.where(labels == label)[0]

    threshold = len(indexes) * 80 // 100

    training_indexes = indexes[0:threshold]
    training_files_for_class = [files[i] for i in training_indexes]

    training_files.extend(training_files_for_class)
    training_labels.extend([label] * len(training_files_for_class))

    validation_indexes = indexes[threshold:]
    validation_files_for_class = [files[i] for i in validation_indexes]

    validation_files.extend(validation_files_for_class)
    validation_labels.extend([label] * len(validation_files_for_class))