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R Deep Learning Cookbook

You're reading from   R Deep Learning Cookbook Solve complex neural net problems with TensorFlow, H2O and MXNet

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Product type Paperback
Published in Aug 2017
Publisher Packt
ISBN-13 9781787121089
Length 288 pages
Edition 1st Edition
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Authors (2):
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Achyutuni Sri Krishna Rao Achyutuni Sri Krishna Rao
Author Profile Icon Achyutuni Sri Krishna Rao
Achyutuni Sri Krishna Rao
PKS Prakash PKS Prakash
Author Profile Icon PKS Prakash
PKS Prakash
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Toc

Table of Contents (11) Chapters Close

Preface 1. Getting Started FREE CHAPTER 2. Deep Learning with R 3. Convolution Neural Network 4. Data Representation Using Autoencoders 5. Generative Models in Deep Learning 6. Recurrent Neural Networks 7. Reinforcement Learning 8. Application of Deep Learning in Text Mining 9. Application of Deep Learning to Signal processing 10. Transfer Learning

Defining placeholder variables


In this recipe, let's define the placeholder variables that serve as input to the modules in a TensorFlow computational graph. These are typically multidimensional arrays or matrices in the form of tensors.

Getting ready

The data type of placeholder variables is set to float32 (tf$float32) and the shape is set to a two-dimensional tensor.

How to do it...

  1. Create an input placeholder variable:
x = tf$placeholder(tf$float32, shape=shape(NULL, img_size_flat), name='x')

The NULL value in the placeholder allows us to pass non-deterministic arrays size.

  1. Reshape the input placeholder x into a four-dimensional tensor:
x_image = tf$reshape(x, shape(-1L, img_size, img_size, num_channels))
  1. Create an output placeholder variable:
y_true = tf$placeholder(tf$float32, shape=shape(NULL, num_classes), name='y_true')
  1. Get the (true) classes of the output using argmax:
y_true_cls = tf$argmax(y_true, dimension=1L)

How it works...

In step 1, we define an input placeholder variable. The dimensions...

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