mnist_general_latent_space_and_generate.py

import numpy as np
import matplotlib.pyplot as plt
from scipy.stats import norm
from mpl_toolkits.mplot3d import Axes3D

import keras
from keras.layers import Input, Dense, Lambda, Layer
from keras.models import Model
from keras import backend as K
from keras import metrics
from keras.datasets import mnist

# parameters
from mnist_params import *

"""
loading vae model back is not a straight-forward task because of custom loss layer.
we have to define some architecture back again to specify custom loss layer and hence to load model back again.
"""

# encoder architecture
x = Input(shape=(original_dim,))
encoder_h = Dense(intermediate_dim, activation='relu')(x)
z_mean = Dense(latent_dim)(encoder_h)
z_log_var = Dense(latent_dim)(encoder_h)

# Custom loss layer
class CustomVariationalLayer(Layer):
    def __init__(self, **kwargs):
        self.is_placeholder = True
        super(CustomVariationalLayer, self).__init__(**kwargs)

    def vae_loss(self, x, x_decoded_mean):
        xent_loss = original_dim * metrics.binary_crossentropy(x, x_decoded_mean)
        kl_loss = - 0.5 * K.sum(1 + z_log_var - K.square(z_mean) - K.exp(z_log_var), axis=-1)
        return K.mean(xent_loss + kl_loss)

    def call(self, inputs):
        x = inputs[0]
        x_decoded_mean = inputs[1]
        loss = self.vae_loss(x, x_decoded_mean)
        self.add_loss(loss, inputs=inputs)
        # We won't actually use the output.
        return x

# load saved models
vae = keras.models.load_model('../models/ld_%d_id_%d_e_%d_vae.h5' % (latent_dim, intermediate_dim, epochs),
    custom_objects={'latent_dim':latent_dim, 'epsilon_std':epsilon_std, 'CustomVariationalLayer':CustomVariationalLayer})
encoder = keras.models.load_model('../models/ld_%d_id_%d_e_%d_encoder.h5' % (latent_dim, intermediate_dim, epochs),
    custom_objects={'latent_dim':latent_dim, 'epsilon_std':epsilon_std, 'CustomVariationalLayer':CustomVariationalLayer})
generator = keras.models.load_model('../models/ld_%d_id_%d_e_%d_generator.h5' % (latent_dim, intermediate_dim, epochs),
    custom_objects={'latent_dim':latent_dim, 'epsilon_std':epsilon_std, 'CustomVariationalLayer':CustomVariationalLayer})



# load dataset
(x_train, y_train), (x_test, y_test) = mnist.load_data()
x_train = x_train.astype('float32') / 255.
x_test = x_test.astype('float32') / 255.
x_train = x_train.reshape((len(x_train), np.prod(x_train.shape[1:])))
x_test = x_test.reshape((len(x_test), np.prod(x_test.shape[1:])))


# display a 2D or 3D plot of the digit classes in the latent space
if latent_dim == 2 or latent_dim==3:
    if latent_dim == 2:
        x_test_encoded = encoder.predict(x_test, batch_size=batch_size)
        plt.figure(figsize=(6, 6))
        # print "hi"
        plt.scatter(x_test_encoded[:, 0], x_test_encoded[:, 1], c=y_test)
        plt.colorbar()
        plt.show()
    else:
        x_test_encoded = encoder.predict(x_test, batch_size=batch_size)
        # plt.figure(figsize=(6, 6))
        fig = plt.figure(figsize=(12,12))
        ax = fig.add_subplot(111, projection='3d')
        #for x, y, z in zip(x_test_encoded[:, 1], x_test_encoded[:, 2],x_test_encoded[:, 3]):
        #    ax.scatter(x, y,z, c=y_test)


        ax.scatter(x_test_encoded[:, 0], x_test_encoded[:, 1],x_test_encoded[:, 2], c=y_test)
        #plt.colorbar()
        plt.show()



# display a 2D manifold of the images
n = 25  # figure with 15x15 digits
digit_size = 28
figure = np.zeros((digit_size * n, digit_size * n))
# linearly spaced coordinates on the unit square were transformed through the inverse CDF (ppf) of the Gaussian
# to produce values of the latent variables z, since the prior of the latent space is Gaussian


for i in range(n):
    for j in range(n):
        z_sample = np.array([np.random.uniform(-1.5, 1.5,size=latent_dim)])
        x_decoded = generator.predict(z_sample)
        digit = x_decoded[0].reshape(digit_size, digit_size)
        figure[i * digit_size: (i + 1) * digit_size,j * digit_size: (j + 1) * digit_size] = digit

plt.figure(figsize=(20, 20))
plt.imshow(figure, cmap='Greys_r')
plt.show()