Teaching Data Science Students to Write Clean Code Todd Iverson, Winona State University Slides/Code: https://bit.ly/2WgFIbI Episode 37 Doug Wants an A The Hero I NEED an A! The Villain Hi! I’m Doug Grrr Doug? An A? HA! His code stinks! Doug “Crazy Legs” Ervison “Mean” Dr. Iverson Doug will demonstrate 1. Good names 2. Small functions 3. Unit tests 4. Refactor code, specifically 1. Extract functions 2. Split loops Opening Scene - The Assignment But Dr. Iverson is SO mean! Kaggle is Kool! Kaggle assignment! https://www.kaggle.com/c/spooky-author-identification/data (…this assignment require unit tests!…) Doug’s Original code (…F!…) Iverson loves Bag of Words! I am going to get an A for sure! It looks like our hero is doomed to an F! Then just in the nick of time … … Doug remembers unit tests! You MUST have unit tests. What are unit tests? Captures/maintain intended behavior Helpful when changing code Should be automated Doug writes some unit tests Original behavior New behavior That was easy! And my code passed! (…with names like that …) Doug’s Original code (…a C at best…) Remembered the Unit Tests! I am going to get an A for sure! Luckily, Doug remembers to think about names Names are important! They should express intent! Good names… Reveal intent Use the proper parts of speech Have the proper length for their scope Avoids disinformation and encodings Data: What is it? Function: What does it do? Good names… Reveal intent Use the proper parts of speech Have the proper length for their scope Avoids disinformation and encodings Variable: Noun Function: Verb Boolean: Predicate Doug inspects his names These names are bad. What’ ews again?? Doug finds some better names ews hold the words for Edgar Allen Poe Maybe I should just use poe_words A+ for sure! (…D at best…) poe_words is better than ews (…see the bug?…) The other names are better too! It looks like our hero is doomed with D! Then just in the nick

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