This note is based on chapter "Driving Visual Analyses with Automobile Data" in book "Practical Data Science Cookbook" by Tony Ojeda, etc.
Domain knowledge
Feature comb08 represents combine fuel efficiency (in Chapter 2, page 43); displ represents the engine displacement in liters (in page 206); atvType represents alternative or advanced technology vehicle (in chaper 2, page 33).
The same place for explanations of feature barrels08, barrelsA08, charge120, charge240.
Python Implementation
pandas.melt convert a dataframe from wide format (宽表) to a long format.
The converting rule based on distingishing all the columns from id, variable (like dimension in BI) and value (like measure in BI).