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README.md

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 # Making Attractive 2-D Vector Diagrams in Python with PlotVec
 
-*How do I make attractive vector diagrams in Python?* PlotVec makes plotting vectors easier.
+*How do I make attractive vector diagrams in Python?* PlotVec makes plotting vectors easier.  PlotVec was created to enable interactive quizzes for readers of my book [*Foundations of Data Science with Python*](https://amzn.to/48cYila) [Affilate Link]
 
 (Note that the figures below use my matplotlibrc file, which is included in the GitHub repository for plotvec.)
 
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 The graphs show that the rectangular field of input points (on the left) is transformed into a parallelogram of points at the output (on the right).
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+**As an Amazon Associate I earn from qualifying purchases.**
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