Python One-Liners: Sampling A 2D Python List (to Speed Up Machine Learning)

This is a tutorial video from my new book “Python One-Liners” with NoStarch press (San Francisco 2020).

Grab your Python One-Liner Superpower now! (Amazon Link)

Here’s the code that shows you how to sample a two-dimensional Python list—including only every other list element in the resulting two-dimensional Python list. All of this happens in a single line of code:

## Data (daily stock prices ($))
price = [[9.9, 9.8, 9.8, 9.4, 9.5, 9.7],
         [9.5, 9.4, 9.4, 9.3, 9.2, 9.1],
         [8.4, 7.9, 7.9, 8.1, 8.0, 8.0],
         [7.1, 5.9, 4.8, 4.8, 4.7, 3.9]]

sample = [line[::2] for line in price]

print(sample)
# [[9.9, 9.8, 9.5], [9.5, 9.4, 9.2], [8.4, 7.9, 8.0], [7.1, 4.8, 4.7]]

Try it yourself:

The code simply removes every other element from each row in the 2D matrix.

Check out the following Finxter tutorials to learn about the necessary background:

Related articles:

• List Comprehension
• Slicing
• NumPy
• Python Lists