# Copyright (c) Microsoft Corporation. All rights reserved.
# Licensed under the MIT License.

import gzip
import numpy as np
import struct


# load compressed MNIST gz files and return numpy arrays
def load_data(filename, label=False):
    with gzip.open(filename) as gz:
        struct.unpack('I', gz.read(4))
        n_items = struct.unpack('>I', gz.read(4))
        if not label:
            n_rows = struct.unpack('>I', gz.read(4))[0]
            n_cols = struct.unpack('>I', gz.read(4))[0]
            res = np.frombuffer(gz.read(n_items[0] * n_rows * n_cols), dtype=np.uint8)
            res = res.reshape(n_items[0], n_rows * n_cols)
        else:
            res = np.frombuffer(gz.read(n_items[0]), dtype=np.uint8)
            res = res.reshape(n_items[0], 1)
    return res


# one-hot encode a 1-D array
def one_hot_encode(array, num_of_classes):
    return np.eye(num_of_classes)[array.reshape(-1)]