utils.py

import os
import numpy as np
from cntk.io import (MinibatchSource, CTFDeserializer, StreamDef, StreamDefs,
                     INFINITELY_REPEAT, FULL_DATA_SWEEP)

import matplotlib.pyplot as plt
import imageio


def check_path(path):
    if not os.path.exists(path):
        readme_file = os.path.normpath(os.path.join(
            os.path.dirname(path), "..", "README.md"))
        raise RuntimeError(
            "File '%s' does not exist. Please follow the instructions at %s to download and prepare it." % (path, readme_file))


def create_reader(path, is_training, input_dim):
    return MinibatchSource(CTFDeserializer(path, StreamDefs(
        features  = StreamDef(field='features', shape=input_dim, is_sparse=False),
    )), randomize=is_training, max_sweeps = INFINITELY_REPEAT if is_training else 1)


np.random.seed(np.random.randint(100))
def noise_sample(num_samples, embedding):
    return np.random.uniform(
        low = -1.0,
        high = 1.0,
        size = [num_samples, embedding]
    ).astype(np.float32)


def plot_images(images, subplot_shape):
    plt.style.use('ggplot')
    fig, axes = plt.subplots(*subplot_shape)
    for image, ax in zip(images, axes.flatten()):
        ax.imshow(image.reshape(28, 28), vmin=0, vmax=1.0, cmap='gray')
        ax.axis('off')
    plt.show()


def save_images(images, size, image_path=''):
    if len(images.shape) == 3:  # Greyscale [batch, h, w] --> [batch, h, w, 1]
        images = images[:, :, :, np.newaxis]

    def merge(images, size):
        h, w = images.shape[1], images.shape[2]
        img = np.zeros((h * size[0], w * size[1], 3), dtype=images.dtype)
        for idx, image in enumerate(images):
            i = idx % size[1]
            j = idx // size[1]
            img[j * h:j * h + h, i * w:i * w + w, :] = image
        return img

    def imsave(images, size, path):
        return imageio.imwrite(path, merge(images, size))

    assert len(images) <= size[0] * size[1], "number of images should be equal or less than size[0] * size[1] {}".format(len(images))
    return imsave(images, size, image_path)


def exists_or_mkdir(path):
    if not os.path.exists(path):
        os.makedirs(path)
        return False
    else:
        return True