Here's all the code and examples from my book Data Science from Scratch. The code directory contains Python 2.7 versions, and the code-python3 direction contains the Python 3 equivalents. (I tested them in 3.5, but they should work in any 3.x.)
July 2018: I am currently working on the second edition. It will be based on Python 3.6, will have much cleaner code, and will contain expanded coverage of deep learning, NLP, and whatever else I feel like adding. Stay tuned.
Each can be imported as a module, for example (after you cd into the /code directory):
from linear_algebra import distance, vector_mean
v = [1, 2, 3]
w = [4, 5, 6]
print distance(v, w)
print vector_mean([v, w])Or can be run from the command line to get a demo of what it does (and to execute the examples from the book):
python recommender_systems.pyAdditionally, I've collected all the links from the book.
And, by popular demand, I made an index of functions defined in the book, by chapter and page number. The data is in a spreadsheet, or I also made a toy (experimental) searchable webapp.
- Introduction
 - A Crash Course in Python
 - Visualizing Data
 - Linear Algebra
 - Statistics
 - Probability
 - Hypothesis and Inference
 - Gradient Descent
 - Getting Data
 - Working With Data
 - Machine Learning
 - k-Nearest Neighbors
 - Naive Bayes
 - Simple Linear Regression
 - Multiple Regression
 - Logistic Regression
 - Decision Trees
 - Neural Networks
 - Clustering
 - Natural Language Processing
 - Network Analysis
 - Recommender Systems
 - Databases and SQL
 - MapReduce
 - Go Forth And Do Data Science