Module 00 · Handling data

Records and formats

What a record is, why the file you were sent is not the table you wanted, and how to get from one to the other without pretending the mess is not there.

3 lessons · 2 graded exercises·2 hours·beginner·No prerequisites

What a record is

20 min

A row is a claim about something that happened. Most of the difficulty in this job comes from rows that make a claim they cannot support, and from pipelines that pass them along anyway.

Reading a messy file

25 min · exercise

Parse a delimited file by hand once, so you know exactly what the csv module is doing for you and exactly which of your assumptions it does not share.

Shapes that nest

25 min · exercise

JSON carries types and nests, which solves the quoting problem and creates the flattening problem. Deciding how a document becomes a row is a design decision, not a mechanical one.