Book Image

NumPy: Beginner's Guide

By : Ivan Idris
Book Image

NumPy: Beginner's Guide

By: Ivan Idris

Overview of this book

Table of Contents (21 chapters)
NumPy Beginner's Guide Third Edition
Credits
About the Author
About the Reviewers
www.PacktPub.com
Preface
NumPy Functions' References
Index

Time for action – plotting price and volume returns with a scatter plot


We can easily make a scatter plot of the stock price and volume returns. Again, let's download the necessary data from Yahoo Finance.

  1. The quotes data in the previous step is stored in a Python list. Convert this to a NumPy array and extract the close and volume values:

    dates = quotes.T[4]
    volume = quotes.T[5]
  2. Calculate the close price and volume returns:

    ret = np.diff(close)/close[:-1]
    volchange = np.diff(volume)/volume[:-1]
  3. Create a matplotlib figure object:

    fig = plt.figure()
  4. Add a subplot to the figure:

    ax = fig.add_subplot(111)
  5. Create the scatter plot with the color of the data points linked to the close return, and the size linked to the volume change:

    ax.scatter(ret, volchange, c=ret * 100, s=volchange * 100, alpha=0.5)
  6. Set the title of the plot and put a grid on it:

    ax.set_title('Close and volume returns')
    ax.grid(True)
    
    plt.show()

    The scatter plot for DISH appears as follows:

What just happened?

We made a scatter plot of...