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R Deep Learning Cookbook

You're reading from  R Deep Learning Cookbook

Product type Book
Published in Aug 2017
Publisher Packt
ISBN-13 9781787121089
Pages 288 pages
Edition 1st Edition
Languages
Authors (2):
PKS Prakash PKS Prakash
Profile icon PKS Prakash
Achyutuni Sri Krishna Rao Achyutuni Sri Krishna Rao
Profile icon Achyutuni Sri Krishna Rao
View More author details
Toc

Table of Contents (17) Chapters close

Title Page
Credits
About the Authors
About the Reviewer
www.PacktPub.com
Customer Feedback
Preface
1. Getting Started 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 the cost function used for optimization


The cost function is primarily used to evaluate the current performance of the model by comparing the true class labels (y_true_cls) with the predicted class labels (y_pred_cls). Based on the current performance, the optimizer then fine-tunes the network parameters, such as weights and biases, to further improve its performance.

Getting ready

The cost function definition is critical as it will decide optimization criteria. The cost function definition will require true classes and predicted classes to do comparison. The objective function used in this recipe is cross entropy, used in multi-classification problems.

How to do it...

  1. Evaluate the current performance of each image using the cross entropy function in TensorFlow. As the cross entropy function in TensorFlow internally applies softmax normalization, we provide the output of the fully connected layer post dropout (layer_fc2_drop) as an input along with true labels (y_true):
cross_entropy...
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