# Python Machine Learning

## Sebastian Raschka

Language: English

Pages: 454

ISBN: 1783555130

Format: PDF / Kindle (mobi) / ePub

**Unlock deeper insights into Machine Leaning with this vital guide to cutting-edge predictive analytics**

## About This Book

- Leverage Python's most powerful open-source libraries for deep learning, data wrangling, and data visualization
- Learn effective strategies and best practices to improve and optimize machine learning systems and algorithms
- Ask – and answer – tough questions of your data with robust statistical models, built for a range of datasets

## Who This Book Is For

If you want to find out how to use Python to start answering critical questions of your data, pick up Python Machine Learning – whether you want to get started from scratch or want to extend your data science knowledge, this is an essential and unmissable resource.

## What You Will Learn

- Explore how to use different machine learning models to ask different questions of your data
- Learn how to build neural networks using Pylearn 2 and Theano
- Find out how to write clean and elegant Python code that will optimize the strength of your algorithms
- Discover how to embed your machine learning model in a web application for increased accessibility
- Predict continuous target outcomes using regression analysis
- Uncover hidden patterns and structures in data with clustering
- Organize data using effective pre-processing techniques
- Get to grips with sentiment analysis to delve deeper into textual and social media data

## In Detail

Machine learning and predictive analytics are transforming the way businesses and other organizations operate. Being able to understand trends and patterns in complex data is critical to success, becoming one of the key strategies for unlocking growth in a challenging contemporary marketplace. Python can help you deliver key insights into your data – its unique capabilities as a language let you build sophisticated algorithms and statistical models that can reveal new perspectives and answer key questions that are vital for success.

Python Machine Learning gives you access to the world of predictive analytics and demonstrates why Python is one of the world's leading data science languages. If you want to ask better questions of data, or need to improve and extend the capabilities of your machine learning systems, this practical data science book is invaluable. Covering a wide range of powerful Python libraries, including scikit-learn, Theano, and Pylearn2, and featuring guidance and tips on everything from sentiment analysis to neural networks, you'll soon be able to answer some of the most important questions facing you and your organization.

## Style and approach

Python Machine Learning connects the fundamental theoretical principles behind machine learning to their practical application in a way that focuses you on asking and answering the right questions. It walks you through the key elements of Python and its powerful machine learning libraries, while demonstrating how to get to grips with a range of statistical models.

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this task. Estimating probabilities in multi-class classification via the softmax function The softmax function is a generalization of the logistic function that allows us to compute meaningful class-probabilities in multi-class settings (multinomial logistic regression). In softmax, the probability of a particular sample with net input belongs to the th class can be computed with a normalization term in the denominator that is the sum of all linear functions: To see softmax in

correspond to the 50 Iris-Setosa and 50 Iris-Versicolor flowers, respectively, and convert the class labels into the two integer class labels 1 (Versicolor) and -1 (Setosa) that we assign to a vector y where the values method of a pandas DataFrame yields the corresponding NumPy representation. Similarly, we extract the first feature column (sepal length) and the third feature column (petal length) of those 100 training samples and assign them to a feature matrix X, which we can visualize via a

recent worldwide competitions for protein structure prediction and refinement, CASP, in 2012 and 2014. While working on his doctorate degree, he decided to join the Computer Science and Engineering Department at Michigan State University to specialize in the field of machine learning. His current research projects involve the development of unsupervised machine learning algorithms for the mining of massive datasets. He is also a passionate Python programmer and shares his implementations of

Scholkopf, A. Smola, and K.-R. Muller. Kernel Principal Component Analysis. pages 583–588, 1997) so that we can replace the dot products between samples in the original feature space by the nonlinear feature combinations via : To obtain the eigenvectors—the principal components—from this covariance matrix, we have to solve the following equation: Here, and are the eigenvalues and eigenvectors of the covariance matrix , and can be obtained by extracting the eigenvectors of the kernel

approach: In this approach, we use the condensed distance matrix. The code is as follows:>>> row_clusters = linkage(pdist(df, metric='euclidean'), ... method='complete') Correct approach: In this approach, we use the input sample matrix. The code is as follows:>>> row_clusters = linkage(df.values, ... method='complete', ... metric='euclidean') To take a closer look at the clustering results, we can turn them to a pandas DataFrame (best viewed in IPython Notebook) as follows: >>>