Lesson 02

Question 1

Learning Objectives

Answer 1

• diagram the flow of data in solving a problem;
• define relational table structures and schema;
• explain the difference between a matrix and a table;
• use relational structure in tables and using relational algebra;
• explain how tables represent multi-dimensional sparse matrices; and
• recognize basic Python data types for data science.

Question 2

What is the purpose of DFD?

Answer 2

Describe processes that involve the movement and transformation of data.

Question 3

Describe the four elements of a DFD

Answer 3

• Complete Rectangle - either generate or consumer data
• Rectangles without sides - data stores
• Ellipse - a process that transforms data
• Arrow - data

Question 4

Describe the DFD Arrow.

Answer 4

An arrow represents data or data flow. It connects other data flow components. Every component must have at least one arrow.

Question 5

Describe the DFD Process.

Answer 5

An ellipse that represents a process by which data is coming in and out. Implying that there must be at least two arrows. One for data coming in and one for data coming out.

Question 6

Describe the DFD Terminator.

Answer 6

A complete rectangle that represents a process that generates or consumes data. Complete DFD’s will begin and end with terminators.

Question 7

Describe the DFD Store.

Answer 7

An incomplete rectangle it represents a place where data is stored. (e.g. files, websites, db’s) Stores have at least one input and one output arrow that are not typically labelled. The label of a store describes the nature of the data and not the store.