1、排序sorted:将数组按某一值排序
def sort_by_target(mnist): reorder_train = np.array(sorted([(target, i) for i, target in enumerate(mnist.target[:60000])]))[:, 1] reorder_test = np.array(sorted([(target, i) for i, target in enumerate(mnist.target[60000:])]))[:, 1] print(reorder_train.shape) mnist.data[:60000] = mnist.data[reorder_train] mnist.target[:60000] = mnist.target[reorder_train] mnist.data[60000:] = mnist.data[reorder_test + 60000] mnist.target[60000:] = mnist.target[reorder_test + 60000]