Planning phase

Questions

  • How to use UML and Pseudocode?

  • Can we learn it?

Objectives

  • We will give an overview of UML diagrams

    • learn when to use

    • learn basic notations

  • We will see some examples of Pseudocode

Instructor note

Some overview

The planning steps

  1. Analysis

  • Get an overview of the project/program and goals

  • to state the problem and define inputs and outputs

  • Gather requirements

  • graphical tools like UML

  1. Design

  • to find out the specific algorithms needed

  • pseudocode

Analysis step

  • UML Diagrams

    • Flowchart

  • Object-orientation programming

    • Identify objects

  • Functional programming

    • Identify functions

  • Text can also work here, describing the problem as a whole

Design step

  • Pseudocode

  • Object-orientation programming

    • Identify classes that objects can belong to

    • UML

  • Functional programming

    • Identify algorithms

The Planet project

Analysis

Planet project

Background

  • The climate last about 1 million years has been largely determined but the change of the eccentricity (elongation) of Earth’s orbit (One of the Milankovitch cycles.

  • The glacial cycles (daily speaking: ice ages) with a period of about 100 000 years are thought to be due to this.

    • Theory: The gravity from the other planets, especially Jupiter, causes the change of the eccentricity.

  • Problem: Reproduce Milankovitch cycle of eccentricity (100ka)

  • Method: Use Python

    • Let’s go for functional programming

  • Input: Some initial positions of the planets but no external data

    • Perhaps also user input of length of simulation

  • Output: Graph of orbits and a timeseries of an eccentricity parameter

Development steps (we extend the program with iterations)

  1. Earth-sun system

  2. Add Jupiter

  3. Make modular

  4. Add more planets?

PlantUML Cheat sheet

UML code (if this is rendered automatically, turn off the plugin!)

@startuml
skin rose
title Repeat - Activity Diagram

start
repeat
  :Eat Hot Wings;
  :Drink Homebrew;
repeat while (Still Hungry?)
stop
@enduml

UML graph

@startuml skin rose title Repeat - Activity Diagram start repeat :Eat Hot Wings; :Drink Homebrew; repeat while (Still Hungry?) stop @enduml

Let’s make a flowchart of the program parts

Exercise

We want to make a activity diagram of these steps.

I will use https://www.planttext.com/ for this

  • define some parameters

  • initialize earth (and Jupiter later on)

  • repeat until simulation time is met

    • calculate new position

    • calculate acceleration

    • calculate velocity in two dimensions

  • then plot figure

Solution

@startuml
skin rose
title Planet flowchart
start

:define some parameters;
:initialize earth (and Jupiter);

repeat
  :calculate new position;
  :calculate acceleration;
  :calculate velocity in two dimensions;

repeat while (simulation time is met) is (no)
->yes;
:figure plotting;
stop

@enduml

It should look something like this:

@startuml
skin rose
title Planet flowchart
start

:define some parameters;
:initialize earth (and Jupiter);

repeat
  :calculate new position;
  :calculate acceleration;
  :calculate velocity in two dimensions;

repeat while (simulation time is met) is (no)
->yes;
:figure plotting;
stop

See also

Syntax for algorithm flowchart

Design

  • A way to visualize a system’s architectural blueprints in a diagram, including elements such as:

    • any activities (jobs);

    • individual components of the system;

      • and how they can interact with other software components;

    • how the system will run;

    • how entities interact with others (components and interfaces);

    • external user interface.

  • Although originally intended for object-oriented design documentation, UML has been extended to a larger set of design documentation, and been found useful in many contexts.

Note

- Many people jump this step feels it's more comfortable to write in the actual programming language directly
- This will not be covered deeply in the lessons of the week

Example

  algorithm ford-fulkerson is
    input: Graph G with flow capacity c, 
           source node s, 
           sink node t
    output: Flow f such that f is maximal from s to t

    (Note that f(u,v) is the flow from node u to node v, and c(u,v) is the flow capacity from node u to node v)

    for each edge (u, v) in GE do
        f(u, v) ← 0
        f(v, u) ← 0

    while there exists a path p from s to t in the residual network Gf do
        let cf be the flow capacity of the residual network Gf
        cf(p) ← min{cf(u, v) | (u, v) in p}
        for each edge (u, v) in p do
            f(u, v) ←  f(u, v) + cf(p)
            f(v, u) ← −f(u, v)

    return f

Do some pseudocode of the calculations

Demo of Pseudocode

Define constants
Define initial values
	positions
	velocity (balance of gravity and centrifugal force)
(Allocate (book) space for long vectors	plan iteration)
Iteration
	Change of positions
	Calc acc (gravity)
	Calc new velocity
Plot resulting ellipses
Calculate orbit parameters
Plot time series of parameter change

Wrap-up

UML & Pseudocode

Menti

  • I have used it

  • I like it

  • I plan to use it

Note

  • More practicals on UML later this week!

  • Pseudocode will not be covered deeply in the lessons of the week

Parts to be covered

  • ☑ Planning

    • Pseudocode

    • Unified Modelling Language

  • ☐ Testing

    • We don’t do this today!

  • ☐ Source/version control

  • ☐ Collaboration

  • ☐ Sharing

  • ☐ Documentation

Summary

Keypoints

  • UML is good in several conditions

    • Structural overviews

    • Planning

    • Problem solving

    • Designing phase of programming

  • Pseudocode gives a more detailed description what you want the program to do.

    • Can be highly personal or very language-like

    • Many people jump this step feels it’s more comfortable to write in the actual programming language directly