Class 05 – Friday, September 1

It's all about you

Show understanding — Put it altogether now — Yes you all can do

Help crush breast cancer — For your families and friends — Not be asunder

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Look both ways

• Back or ahead

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Downloads — get them all, some have been updated

• Program cast_away.py

• Program favorite_word.py

• Program combine_replicate.py

• Program hip_hopping.py

• Program complimenter.py

• Program dateable.py

 

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Agenda

• Further expand our communication skills

• Introduce Python string operators + and *

• Get adept at casting

• Demonstrate your own chresthomatics abilities by solving and submitting problem solutions before the end of class.

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Future homework requirements and facts

• A numeric value display must be from the value of a variable; i.e., there will never be arithmetic calculations within a print() statement.

• All variables should be named indicating their purpose/usage.

• Always end each prompt with a space; e.g., input( 'What is something you consume daily?: ' )

• The grading of your programs will use inputs different from those shown in problem discussion.

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Program cast_away.py

• Problem

• Demonstrate how to convert values of one type to values of other types

• Program run

i: 1

f: 2.9

c: '33'

d: '4.5'

int( f ): 2

float( i ): 1.0

int( c ): 33

float( d ): 4.5

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Program favorite_word.py

• Problem

• Prompt and get a word of interest from user user

• Compute the length of the word

• Output a message about the length of the word

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• What the solution offers

Another use of the built-in function input().

Introduces the built-in function len().

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• Three possible program runs

Tell me a favorite word: crwth

 

Did you know that crwth has length 5

Tell me a favorite word: strengths

 

Did you know that strengths has length 9

Tell me a favorite word: scraunched

 

Did you know that squirreled has length 10

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Program hip_hopping.py

• Problem

• Simulate the number of rabbits occurring over four generations.

• User supplies two value: the number of rabbits in the initial population and the growth rate (the number of new rabbits each rabbit contributes to the next generation)

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• What the solution offers

• Converts input into integer values

• Examines nuances of the assignment operator.

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• Two possible program runs

How many rabbits: 2

Growth rate per generation: 2

Generation: 1

Rabbits: 2

Generation: 2

Rabbits: 4

Generation: 3

Rabbits: 8

Generation: 4

Rabbits: 16

How many rabbits: 6

Growth rate per generation: 2

Generation: 1

Rabbits: 6

Generation: 2

Rabbits: 12

Generation: 3

Rabbits: 24

Generation: 4

Rabbits: 48

How many rabbits: 4

Growth rate per generation: 5

Generation: 1

Rabbits: 4

Generation: 2

Rabbits: 20

Generation: 3

Rabbits: 100

Generation: 4

Rabbits: 500

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Program combine_replicate.py

• Introduces the string concatenation operator + and replication operator *.

• Some possible progrm runs

Enter word: fire

Enter word: fighter

Enter phrase: Wah-Hoo-Wah!

word1: fire

word2: fighter

phrase: Wah-Hoo-Wah!

### operator + performs concatenation

word1 + word2: firefighter

### operator * performs concatenation

n: 3

n * phrase: Wah-Hoo-Wah!Wah-Hoo-Wah!Wah-Hoo-Wah!

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Program complimenter.py

• Problem

• For a single user-supplied integer age, print out a tasteful compliment based on the supplied age.

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• Requirements

• The faux (complimentary) age is the user-supplied age minus five years.

• The faux age is to be integer.

• The program does not attempt to get more than one input from the user.

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• Three different possible program runs

• The above section header means what it literally says. The below boxes each show a different program run; i.e., your program is to perform a single age calculation each time it is run.

  Enter your age: 19

  You don’t even look 14

  Enter your age: 111

  You don’t even look 106

  Enter your age: 20

  You don’t even look 15

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• Suggested code outline

• Prompt user to supply an age

• Convert user reply to integer

• Compute supposed age

• Print the result of the computation

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Program dateable.py

• Problem description

• For a single user-supplied age, tell them how old a person must be to have dating be acceptable according to the following folk rule:

• You should only date someone who is at least seven years older than than half your age.

• For example, an 18 year old needs to date somebody at least 16 year's old (i.e., 7 + ( 18 / 2 ) ).

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• Requirements

• The dateable age is to be calculated by using the above folk rule.

• Use separate variables for storing the user-supplied and dateable ages.

• The displayed dateable age is to be integer.

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• Three different possible program runs

  Enter your age (integer): 19

  19 year olds should date somebody who is at least 16 years old

  Enter your age (integer): 22

  22 year olds should date somebody who is at least 18 years old

  Enter your age (integer): 88

  88 year olds should date somebody who is at least 51 years old

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• Suggested algorithm

• Prompt user to supply an integer age

• Convert user reply to integer

• Compute minimum age according to dateability formula

• Print the result of the computation

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To do list

• Review class artifacts

• Ensure familarity with Python variables, assignment, and input

• Definitely check out the string module. It will be a major topic next week

• Reread the epistle on variety.py

• Complete current assignments as soon as possible for your own sake.

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