# How can Tensorflow be used to prepare the IMDB dataset for training in Python?

PythonServer Side ProgrammingProgramming

Tensorflow is a machine learning framework that is provided by Google. It is an open−source framework used in conjunction with Python to implement algorithms, deep learning applications and much more. It is used in research and for production purposes. It has optimization techniques that help in performing complicated mathematical operations quickly.

The ‘tensorflow’ package can be installed on Windows using the below line of code −

pip install tensorflow

Tensor is a data structure used in TensorFlow. It helps connect edges in a flow diagram. This flow diagram is known as the ‘Data flow graph’. Tensors are nothing but multidimensional array or a list.

The ‘IMDB’ dataset contains reviews of over 50 thousand movies. This dataset is generally used with operations associated with Natural Language Processing.

We are using the Google Colaboratory to run the below code. Google Colab or Colaboratory helps run Python code over the browser and requires zero configuration and free access to GPUs (Graphical Processing Units). Colaboratory has been built on top of Jupyter Notebook.

Following is the code snippet for IMDB dataset −

## Example

def vectorize_text(text, label):
text = tf.expand_dims(text, −1)
return vectorize_layer(text), label

text_batch, label_batch = next(iter(raw_train_ds))
first_review, first_label = text_batch[0], label_batch[0]
print("Review is ", first_review)
print("Label is ", raw_train_ds.class_names[first_label])
print("Vectorized review is ", vectorize_text(first_review, first_label))

print("1222 −−−> ",vectorize_layer.get_vocabulary()[1222])
print(" 451 −−−> ",vectorize_layer.get_vocabulary()[451])
print('Vocabulary size: {}'.format(len(vectorize_layer.get_vocabulary())))

train_ds = raw_train_ds.map(vectorize_text)
val_ds = raw_val_ds.map(vectorize_text)
test_ds = raw_test_ds.map(vectorize_text)

## Output

Review is tf.Tensor(b'Silent Night, Deadly Night 5 is the very last of the series, and like part 4, it\'s unrelated to the first three except by title and the fact that it\'s a Christmas-themed horror flick.<br /><br />Except to the oblivious, there\'s some obvious things going on here...Mickey Rooney plays a toymaker named Joe Petto and his creepy son\'s name is Pino. Ring a bell, anyone? Now, a little boy named Derek heard a knock at the door one evening, and opened it to find a present on the doorstep for him. Even though it said "don\'t open till Christmas", he begins to open it anyway but is stopped by his dad, who scolds him and sends him to bed, and opens the gift himself. Inside is a little red ball that sprouts Santa arms and a head, and proceeds to kill dad. Oops, maybe he should have left well-enough alone. Of course Derek is then traumatized by the incident since he watched it from the stairs, but he doesn\'t grow up to be some killer Santa, he just stops talking.<br /><br />There\'s a mysterious stranger lurking around, who seems very interested in the toys that Joe Petto makes. We even see him buying a bunch when Derek\'s mom takes him to the store to find a gift for him to bring him out of his trauma. And what exactly is this guy doing? Well, we\'re not sure but he does seem to be taking these toys apart to see what makes them tick. He does keep his landlord from evicting him by promising him to pay him in cash the next day and presents him with a "Larry the Larvae" toy for his kid, but of course "Larry" is not a good toy and gets out of the box in the car and of course, well, things aren\'t pretty.<br /><br />Anyway, eventually what\'s going on with Joe Petto and Pino is of course revealed, and as with the old story, Pino is not a "real boy". Pino is probably even more agitated and naughty because he suffers from "Kenitalia" (a smooth plastic crotch) so that could account for his evil ways. And the identity of the lurking stranger is revealed too, and there\'s even kind of a happy ending of sorts. Whee.<br /><br />A step up from part 4, but not much of one. Again, Brian Yuzna is involved, and Screaming Mad George, so some decent special effects, but not enough to make this great. A few leftovers from part 4 are hanging around too, like Clint Howard and Neith Hunter, but that doesn\'t really make any difference. Anyway, I now have seeing the whole series out of my system. Now if I could get some of it out of my brain. 4 out of 5.', shape=(), dtype=string)
Label is neg
Vectorized review is (<tf.Tensor: shape=(1, 250), dtype=int64, numpy=
array([[1287, 313, 2380, 313, 661, 7, 2, 52, 229, 5, 2,
200, 3, 38, 170, 669, 29, 5492, 6, 2, 83, 297,
549, 32, 410, 3, 2, 186, 12, 29, 4, 1, 191,
510, 549, 6, 2, 8229, 212, 46, 576, 175, 168, 20,
1, 5361, 290, 4, 1, 761, 969, 1, 3, 24, 935,
2271, 393, 7, 1, 1675, 4, 3747, 250, 148, 4, 112,
436, 761, 3529, 548, 4, 3633, 31, 2, 1331, 28, 2096,
3, 2912, 9, 6, 163, 4, 1006, 20, 2, 1, 15,
85, 53, 147, 9, 292, 89, 959, 2314, 984, 27, 762,
6, 959, 9, 564, 18, 7, 2140, 32, 24, 1254, 36,
1, 85, 3, 3298, 85, 6, 1410, 3, 1936, 2, 3408,
301, 965, 7, 4, 112, 740, 1977, 12, 1, 2014, 2772,
3, 4, 428, 3, 5177, 6, 512, 1254, 1, 278, 27,
139, 25, 308, 1, 579, 5, 259, 3529, 7, 92, 8981,
32, 2, 3842, 230, 27, 289, 9, 35, 2, 5712, 18,
27, 144, 2166, 56, 6, 26, 46, 466, 2014, 27, 40,
2745, 657, 212, 4, 1376, 3002, 7080, 183, 36, 180, 52,
920, 8, 2, 4028, 12, 969, 1, 158, 71, 53, 67,
85, 2754, 4, 734, 51, 1, 1611, 294, 85, 6, 2,
1164, 6, 163, 4, 3408, 15, 85, 6, 717, 85, 44,
5, 24, 7158, 3, 48, 604, 7, 11, 225, 384, 73,
65, 21, 242, 18, 27, 120, 295, 6, 26, 667, 129,
4028, 948, 6, 67, 48, 158, 93, 1]])>, <tf.Tensor: shape=(), dtype=int32, numpy=0>)
1222 ---> stick
Vocabulary size: 10000

## Explanation

• A function named ‘vectorize_text’ is defined, that basically converts the given text into numbers so that it can be understood by the computer.

• The IMDB dataset is used to train the model.

• A sample of the review, label, and the vectorised data is displayed on the console.

• The training data, test data and validation data are all vectorised.

Published on 19-Jan-2021 13:42:49