Python Data Visualization Cookbook (Second Edition)

Python Data Visualization Cookbook (Second Edition)

Overview of this book

Python Data Visualization Cookbook will progress the reader from the point of installing and setting up a Python environment for data manipulation and visualization all the way to 3D animations using Python libraries. Readers will benefit from over 60 precise and reproducible recipes that will guide the reader towards a better understanding of data concepts and the building blocks for subsequent and sometimes more advanced concepts. Python Data Visualization Cookbook starts by showing how to set up matplotlib and the related libraries that are required for most parts of the book, before moving on to discuss some of the lesser-used diagrams and charts such as Gantt Charts or Sankey diagrams. Initially it uses simple plots and charts to more advanced ones, to make it easy to understand for readers. As the readers will go through the book, they will get to know about the 3D diagrams and animations. Maps are irreplaceable for displaying geo-spatial data, so this book will also show how to build them. In the last chapter, it includes explanation on how to incorporate matplotlib into different environments, such as a writing system, LaTeX, or how to create Gantt charts using Python.

Python Data Visualization Cookbook Second Edition

Credits

About the Authors

About the Reviewer

www.PacktPub.com

Preface

Free Chapter

Preparing Your Working Environment

Introduction

Installing matplotlib, NumPy, and SciPy

Installing virtualenv and virtualenvwrapper

Installing matplotlib on Mac OS X

Installing matplotlib on Windows

Installing Python Imaging Library (PIL) for image processing

Installing a requests module

Customizing matplotlib's parameters in code

Customizing matplotlib's parameters per project

Knowing Your Data

Introduction

Importing data from CSV

Importing data from Microsoft Excel files

Importing data from fixed-width data files

Importing data from tab-delimited files

Importing data from a JSON resource

Exporting data to JSON, CSV, and Excel

Importing and manipulating data with Pandas

Importing data from a database

Cleaning up data from outliers

Reading files in chunks

Reading streaming data sources

Importing image data into NumPy arrays

Generating controlled random datasets

Smoothing the noise in real-world data

Drawing Your First Plots and Customizing Them

Introduction

Defining plot types – bar, line, and stacked charts

Drawing simple sine and cosine plots

Defining axis lengths and limits

Defining plot line styles, properties, and format strings

Setting ticks, labels, and grids

Adding legends and annotations

Moving spines to the center

Making histograms

Making bar charts with error bars

Making pie charts count

Plotting with filled areas

Making stacked plots

Drawing scatter plots with colored markers

More Plots and Customizations

Introduction

Setting the transparency and size of axis labels

Adding a shadow to the chart line

Adding a data table to the figure

Using subplots

Customizing grids

Creating contour plots

Filling an under-plot area

Drawing polar plots

Visualizing the filesystem tree using a polar bar

Customizing matplotlib with style

Making 3D Visualizations

Introduction

Creating 3D bars

Creating 3D histograms

Animating in matplotlib

Animating with OpenGL

Plotting Charts with Images and Maps

Introduction

Processing images with PIL

Plotting with images

Displaying images with other plots in the figure

Plotting data on a map using Basemap

Plotting data on a map using the Google Map API

Generating CAPTCHA images

Using the Right Plots to Understand Data

Introduction

Understanding logarithmic plots

Understanding spectrograms

Creating stem plot

Drawing streamlines of vector flow

Using colormaps

Using scatter plots and histograms

Plotting the cross correlation between two variables

Importance of autocorrelation

Installing matplotlib on Mac OS X

The easiest way to get matplotlib on the Mac OS X is to use prepackaged python distributions such as Enthought Python Distribution (EPD). Just go to the EPD site, and download and install the latest stable version for your OS.

In case you are not satisfied with EPD or cannot use it for other reasons such as the versions distributed with it, there is a manual (read: harder) way of installing Python, matplotlib, and its dependencies.

Getting ready

We will use the Homebrew (you could also use MacPorts in the same way) project that eases the installation of all software that Apple did not install on your OS, including Python and matplotlib. Under the hood, Homebrew is a set of Ruby and Git that automate download and installation. Following these instructions should get the installation working. First, we will install Homebrew, and then Python, followed by tools such as virtualenv, then dependencies for matplotlib (NumPy and SciPy), and finally matplotlib. Hold on, here we go.

How to do it...

In your terminal, paste and execute the following command:
```
ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"
```
After the command finishes, try running brew update or brew doctor to verify that the installation is working properly.
Next, add the Homebrew directory to your system path, so the packages you install using Homebrew have greater priority than other versions. Open ~/.bash_profile (or /Users/[your-user-name]/.bash_profile) and add the following line to the end of file:
```
export PATH=/usr/local/bin:$PATH
```
You will need to restart the terminal so that it picks a new path. Installing Python is as easy as firing up another one liner:
```
brew install python --framework --universal
```
This will also install any prerequisites required by Python.
Now, you need to update your path (add to the same line):
```
export PATH=/usr/local/share/python:/usr/local/bin:$PATH
```
To verify that the installation has worked, type python --version in the command line, you should see 2.7.3 as the version number in the response.
You should have pip installed by now. In case it is not installed, use easy_install to add pip:
```
$ easy_install pip
```
Now, it's easy to install any required package; for example, virtualenv and virtualenvwrapper are useful:
```
pip install virtualenv
pip install virtualenvwrapper
```
The next step is what we really wanted to do all along—install matplotlib:
```
pip install numpy
brew install gfortran
pip install scipy
```

Verify that everything is working. Call Python and execute the following commands:

import numpy
print numpy.__version__
import scipy
print scipy.__version__
quit()

Install matplotlib:
```
pip install matplotlib
```

Python Data Visualization Cookbook (Second Edition)

Python Data Visualization Cookbook (Second Edition)

Overview of this book

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Current Title:

Python Data Visualization Cookbook (Second Edition)

Installing matplotlib on Mac OS X

Getting ready

How to do it...