Keras vs. TensorFlow code comparison sources

Question

This isn't really a question that's code-specific, but I haven't been able to find any answers or resources.

I'm currently trying to teach myself some "pure" TensorFlow rather than just using Keras, and I felt that it would be very helpful if there were some sources where they have TensorFlow code and the equivalent Keras code side-by-side for comparison.

Unfortunately, most of the results I find on the Internet talk about performance-wise differences or have very simple comparison examples (e.g. "and so this is why Keras is much simpler to use"). I'm not so much interested in those details as much as I am in the code itself.

Does anybody know if there are any resources out there that could help with this?

Answer 1

Here you have two models, in Tensorflow and in Keras, that are correspondent:

import tensorflow as tf
import numpy as np
import pandas as pd
from keras.datasets import mnist
(x_train, y_train), (x_test, y_test) = mnist.load_data()

Tensorflow

X = tf.placeholder(dtype=tf.float64)
Y = tf.placeholder(dtype=tf.float64)
num_hidden=128

# Build a hidden layer
W_hidden = tf.Variable(np.random.randn(784, num_hidden))
b_hidden = tf.Variable(np.random.randn(num_hidden))
p_hidden = tf.nn.sigmoid( tf.add(tf.matmul(X, W_hidden), b_hidden) )

# Build another hidden layer
W_hidden2 = tf.Variable(np.random.randn(num_hidden, num_hidden))
b_hidden2 = tf.Variable(np.random.randn(num_hidden))
p_hidden2 = tf.nn.sigmoid( tf.add(tf.matmul(p_hidden, W_hidden2), b_hidden2) )

# Build the output layer
W_output = tf.Variable(np.random.randn(num_hidden, 10))
b_output = tf.Variable(np.random.randn(10))
p_output = tf.nn.softmax( tf.add(tf.matmul(p_hidden2, W_output), b_output) )

loss = tf.reduce_mean(tf.losses.mean_squared_error(
        labels=Y,predictions=p_output))
accuracy=1-tf.sqrt(loss)
minimization_op = tf.train.AdamOptimizer(learning_rate=0.01).minimize(loss)

feed_dict = {
    X: x_train.reshape(-1,784),
    Y: pd.get_dummies(y_train)
}
with tf.Session() as session:
    session.run(tf.global_variables_initializer())

    for step in range(10000):
        J_value = session.run(loss, feed_dict)
        acc = session.run(accuracy, feed_dict)
        if step % 100 == 0:
            print("Step:", step, " Loss:", J_value," Accuracy:", acc)

            session.run(minimization_op, feed_dict)
    pred00 = session.run([p_output], feed_dict={X: x_test.reshape(-1,784)})

Keras

import tensorflow as tf
from tensorflow.keras.layers import Input, Dense
from keras.models import Model

l = tf.keras.layers

model = tf.keras.Sequential([
    l.Flatten(input_shape=(784,)),
    l.Dense(128, activation='relu'),
    l.Dense(128, activation='relu'),
    l.Dense(10, activation='softmax')
])

model.compile(loss='categorical_crossentropy', optimizer='adam',metrics = ['accuracy'])

model.summary()

model.fit(x_train.reshape(-1,784),pd.get_dummies(y_train),nb_epoch=15,batch_size=128,verbose=1)

Answer 2

You can take a look to this toy example, but it may be too simple.