Sebastian Raschka, 2019
Python Machine Learning - Code Examples
Chapter 1 does not contain any code examples.
Python is available for all three major operating systems — Microsoft Windows, macOS, and Linux — and the installer, as well as the documentation, can be downloaded from the official Python website: https://www.python.org.
This book is written for Python version >= 3.7.0, and it is recommended
you use the most recent version of Python 3 that is currently available,
although most of the code examples may also be compatible with older versions of Python 3 and Python >= 2.7.10. If you decide to use Python 2.7 to execute the code examples, please make sure that you know about the major differences between the two Python versions. A good summary about the differences between Python 3 and 2.7 can be found at https://wiki.python.org/moin/Python2orPython3.
Note
You can check your current default version of Python by executing
$ python -V
In my case, it returns
Python 3.7.1 :: Continuum Analytics, Inc.
The additional packages that we will be using throughout this book can be installed via the pip installer program, which has been part of the Python standard library since Python 3.3. More information about pip can be found at https://docs.python.org/3/installing/index.html.
After we have successfully installed Python, we can execute pip from the command line terminal to install additional Python packages:
pip install SomePackage
(where SomePackage is a placeholder for numpy, pandas, matplotlib, scikit-learn, and so forth).
Already installed packages can be updated via the --upgrade flag:
pip install SomePackage --upgrade
A highly recommended alternative Python distribution for scientific computing is Anaconda by Continuum Analytics. Anaconda is a free—including commercial use—enterprise-ready Python distribution that bundles all the essential Python packages for data science, math, and engineering in one user-friendly cross-platform distribution. The Anaconda installer can be downloaded at https://docs.anaconda.com/anaconda/install/, and an Anaconda quick start-guide is available at https://docs.anaconda.com/anaconda/user-guide/getting-started/.
After successfully installing Anaconda, we can install new Python packages using the following command:
conda install SomePackage
Existing packages can be updated using the following command:
conda update SomePackage
Throughout this book, we will mainly use NumPy's multi-dimensional arrays to store and manipulate data. Occasionally, we will make use of pandas, which is a library built on top of NumPy that provides additional higher level data manipulation tools that make working with tabular data even more convenient. To augment our learning experience and visualize quantitative data, which is often extremely useful to intuitively make sense of it, we will use the very customizable matplotlib library.
The version numbers of the major Python packages that were used for writing this book are listed below. Please make sure that the version numbers of your installed packages are equal to, or greater than, those version numbers to ensure the code examples run correctly:
- NumPy >= 1.17.4
- SciPy >= 1.3.1
- scikit-learn >= 0.22.0
- matplotlib >= 3.1.0
- pandas >= 0.25.3
Some readers were wondering about the .ipynb of the code files -- these files are IPython notebooks. I chose IPython notebooks over plain Python .py scripts, because I think that they are just great for data analysis projects! IPython notebooks allow us to have everything in one place: Our code, the results from executing the code, plots of our data, and documentation that supports the handy Markdown and powerful LaTeX syntax!
Side Note: "IPython Notebook" recently became the "Jupyter Notebook"; Jupyter is an umbrella project that aims to support other languages in addition to Python including Julia, R, and many more. Don't worry, though, for a Python user, there's only a difference in terminology (we say "Jupyter Notebook" now instead of "IPython Notebook").
The Jupyter notebook can be installed as usually via pip.
$ pip install jupyter notebook
Alternatively, we can use the Conda installer if we have Anaconda or Miniconda installed:
$ conda install jupyter notebook
To open a Jupyter notebook, we cd to the directory that contains your code examples, e.g,.
$ cd ~/code/python-machine-learning-book
and launch jupyter notebook by executing
$ jupyter notebook
Jupyter will start in our default browser (typically running at http://localhost:8888/). Now, we can simply select the notebook you wish to open from the Jupyter menu.
For more information about the Jupyter notebook, I recommend the Jupyter Beginner Guide and Jupyter Notebook Basics.
An alternative to Jupyter Notebook, called Jupyter Lab, was released in 2018. It operates with the same .ipynb file types but offers some extra features in the browser interface. Whether you use Jupyter Notebook or Jupyter Lab is a matter of preference, but
Jupyter Lab can be installed via
$ conda install -c conda-forge jupyterlab
and similar to starting Jupyter Notebooks, you can run the command
$ jupyter lab
in your command line terminal to launch a Jupyter Lab session in your browser. For more information about the Jupyter Lab project, please visit the official documentation at https://jupyterlab.readthedocs.io/en/stable/,