MCS 177 Lab Fall 2014

Sept. 2, 2014

GUSTAVUS ADOLPHUS COLLEGE gustavus.edu

Contact Info

• Course Instructor: Louis Yu lyu@gustavus.edu

• Lab Instructors: • Mike Hvidsten hvidsten@gustavus.edu• Jeff Engelhardt jengelha@gustavus.edu

• Lab Assistants11:30: Andrew Haisting (ahaistin@gustavus.edu) 2:30: Dustin Luhmann (dluhmann@gustavus.edu)

MCS 177, 9/2/14

GUSTAVUS ADOLPHUS COLLEGE gustavus.edu

Today’s schedule

•C

ourse/Lab Details

•P

ython and Idle

•P

ython Intro (Sec 1.1-1.5 in textbook)

•T

asks 1 and 2 of Project 1 (if time)

MCS 177, 9/2/14

GUSTAVUS ADOLPHUS COLLEGE gustavus.edu

Course/Lab

•C

ourse Website: www.gac.edu/~lyu/teaching/mcs177-f14/

•L

ectures – Monday, Wednesday, Friday

• Read Assigned sections before class (see class schedule)

•L

ab Work – Tuesday, Thursday

• Projects are linked from course site

• This week – Intro (nothing to hand in)

• Submit code via Moodle

•L

ab notes/slides at www.gac.edu/~hvidsten/courses/MC177

MCS 177, 9/2/14

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Python – Course Programming Language

• Python is an open source scripting language.

• Developed by Guido van Rossum in the early 1990s

• Named after Monty Python

• Available on MCS computers

• Available for download from

http://www.python.org

MCS 177, 9/2/14

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Why Python?

MCS 177, 9/2/14

•Simple Syntax – we can focus on solving problems,

learning concepts, not coding syntax

•Object-Oriented – all values are essentially objects

•Widely used (Google spider and search engine)

•Powerful String and Math libraries

•Dynamic Typing: Variables do not need to have pre-

defined types

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Idle GUI Environment:

MCS 177, 9/2/14

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Let’s Get Started!

•L

og on to your computer (user name = email name)

•S

tart Idle

•T

ry some basic arithmetic examples

MCS 177, 9/2/14

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Arithmetic Operations

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Operator Operation

+ Addition

- Subtraction

* Multiplication

/ Float division

// Integer division

% Remainder

** Exponentiation

abs() Absolute value

GUSTAVUS ADOLPHUS COLLEGE gustavus.edu

Numerical Data Types

•I

nteger (int) vs Floating Point (float)

•H

ow can we tell which is which?A numeric value without a decimal point produces an int

valueA numerical value that has a decimal point is represented by

a float (even if the fractional part is 0)

MCS 177, 9/2/14

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Numerical Operations

>>> 3.0+4.07.0>>> 3+47>>> 3.0*412.0>>> 3*412>>> 10.0/3.03.3333333333333335>>> 10/33.3333333333333335>>> 10 // 33>>> 10.0 // 3.03.0

MCS 177, 9/2/14

Operations on ints produce ints (except for /)Operations on floats produce floats,

Mixed operations are converted to floats

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Variable Assignment (Section 1.5)

MCS 177, 9/2/14

•As in mathematics, much of the power of computer

programs is in the use of variables

•Python variables are identified by name

• Must start with a letter

• Ex: x=2, a_1 = x+3

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Example

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•We want to calculate the volume of a cylinder

•volume = area of base * height

•Variables?

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Example

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Diagram for Simple Assignment in Python

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Changing Radius value has no effect on cylinderVolume! Why not?

MCS 177, 9/2/14

10.0

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How do we make change?

MCS 177, 9/2/14

•Need to re-evaluate baseArea and cylinderVolume

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If time, Start working on Tasks 1 and 2 of Project 1

MCS 177, 9/2/14