utils.py

from __future__ import absolute_import
from __future__ import division
from __future__ import print_function

import tensorflow as tf
import numpy as np
import matplotlib.pyplot as plt
from mpl_toolkits.axes_grid1 import ImageGrid

# Model construction utilities below adapted from
# https://www.tensorflow.org/versions/r0.8/tutorials/mnist/pros/index.html#deep-mnist-for-experts
def weight_variable(shape):
    initial = tf.truncated_normal(shape, stddev=0.1)
    return tf.Variable(initial)


def bias_variable(shape):
    initial = tf.constant(0.1, shape=shape)
    return tf.Variable(initial)


def conv2d(x, W):
    return tf.nn.conv2d(x, W, strides=[1, 1, 1, 1], padding='SAME')


def max_pool_2x2(x):
    return tf.nn.max_pool(x, ksize=[1, 2, 2, 1],
                        strides=[1, 2, 2, 1], padding='SAME')


def shuffle_aligned_list(data):
    """Shuffle arrays in a list by shuffling each array identically."""
    num = data[0].shape[0]
    p = np.random.permutation(num)
    return [d[p] for d in data]


def batch_generator(data, batch_size, shuffle=True):
    """Generate batches of data.
    
    Given a list of array-like objects, generate batches of a given
    size by yielding a list of array-like objects corresponding to the
    same slice of each input.
    """
    if shuffle:
        data = shuffle_aligned_list(data)

    batch_count = 0
    while True:
        if batch_count * batch_size + batch_size >= len(data[0]):
            batch_count = 0

            if shuffle:
                data = shuffle_aligned_list(data)

        start = batch_count * batch_size
        end = start + batch_size
        batch_count += 1
        yield [d[start:end] for d in data]


def imshow_grid(images, shape=[2, 8]):
    """Plot images in a grid of a given shape."""
    fig = plt.figure(1)
    grid = ImageGrid(fig, 111, nrows_ncols=shape, axes_pad=0.05)

    size = shape[0] * shape[1]
    for i in range(size):
        grid[i].axis('off')
        grid[i].imshow(images[i])  # The AxesGrid object work as a list of axes.

    plt.show()


def plot_embedding(X, y, d, title=None):
    """Plot an embedding X with the class label y colored by the domain d."""
    x_min, x_max = np.min(X, 0), np.max(X, 0)
    X = (X - x_min) / (x_max - x_min)

    # Plot colors numbers
    plt.figure(figsize=(10,10))
    ax = plt.subplot(111)
    for i in range(X.shape[0]):
        # plot colored number
        plt.text(X[i, 0], X[i, 1], str(y[i]),
                 color=plt.cm.bwr(d[i] / 1.),
                 fontdict={'weight': 'bold', 'size': 9})

    plt.xticks([]), plt.yticks([])
    if title is not None:
        plt.title(title)