Join our Slack Channel

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Slack: https://bit.ly/uwcoffeencodeslack

Channel Name: #war-game

#space-comp for JavaScript

Algorithmic War Game

An introduction to intermediate-level Python

Introductions

Personal Introduction

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Hi, my name is Kevin Bacabac.

• Studying 3B Computer Science
• I like Python
• Second time project lead
• Game developer as a hobby

Who is in this Room? “So tell me about yourself”

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• How many aren’t in Math/Engineering?
• How many people in here confident with Python or another language?
• Anyone in Astronomy or Physics?

• What’s your worst Python install story

Why Python?

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• Commonly used
• Clean syntax
• Faster! (in terms of your own time)

• Gateway to machine learning
• Backend web development
• Useful “glue code”
• Co-op jobs

Project Information

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• We will only be running on Thursdays
• But there is a “twin project” on Wednesday for JavaScript
• We assume you have basic programming capabilities:
• Declaring variables
• If/Else Statements
• For and while loops
• Writing simple functions

^ We’ll review all of these in the first 20 minutes

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Project Information

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• Object-oriented programming, List comprehension, Sets, etc
• Standard Python Package (Typing, Enums, etc)
• Special methods, decorators, fancy stuff

Project Information (Why?)

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• Object-oriented programming
• Lets us reuse code
• Similar to functions but another way of thinking
• Dangerous and powerful tool
• Standard Python Package (Typing, Enums, etc)
• A collection of functions, classes, and other tools that were premade for you

Project Information

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• Reading API Docs and Git
• PEP8 Styling and industry quality code practices
• Eliminating redundancy
• Clean and organized code
• Why learn to use an API?
• Your program can “talk to” a service

Project Schedule

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• Lesson 1
• Python and setup
• Lesson 2
• Python and programming together (50 / 50)

• Lesson 3
• Python and programming custom bots together (30 / 70)
• Lesson 4
• Git and programming (30 / 70)

Project Schedule

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• Lesson 5 / 6
• Continue working on bots and small competitions
• Optional advanced Python modules like hacking the game (but won’t be allowed for competitive matches)
• Maybe special competitions?

We’ll end off spending almost all time programming since writing code is the best way to learn.

Let’s get started

Python Installation

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https://www.python.org/downloads/release/python-376/

Pygame Installation

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• Open a command line or terminal
• pip3 install --user pygame (may try pip instead of pip3)
• Can be quite difficult, ask for help on Slack or look up a guide to pip
• Common Windows issues
• pip not found (try to reinstall Python but make sure it adds itself to PATH)
• Having pre-existing installs

Good luck...

https://xkcd.com/1987/

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Use this to practice code snippets if you don’t have Python.

https://repl.it/

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Git Install (Optional) for Windows

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https://git-scm.com/downloads

Introduction to Git

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• If you downloaded Git you can clone our repository at https://github.com/UWCoffeeNCode/Lessons
• Or you can download a zip file to get started
• We’ll cover Git much later after we’ve covered more Python
• Don’t worry about downloading for now

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Let’s get started

Intro to the War Game

War Game Bots

def action(self, country_status: dict, world_state: dict):

weapon = choice(list(Weapons))

if world_state["alive_players"]:

target = choice(tuple(world_state["alive_players"]))

return {

"Weapon": weapon,

"Target": target

}

return {}

War Game Bots Continued

Bot | Wins | Perc

None | 695 | 33%

Smart Bot | 534 | 25%

Lazy Bot | 289 | 14%

Ping Bot | 280 | 13%

Sample Bot | 112 | 5%

Greedy Bot | 98 | 5%

Class Bot | 92 | 4%

The War Game

Reviewing our Python

Table of Contents�- Variables and types

- If, else if, else syntax

- Operations, + - / * %

- Boolean operations, and, or, not

- Avoiding nested ifs

- For / while loops

- Functions

Variables

• Different types of variables
• int
• str
• float
• Examples

>>> a = 3

>>> b = "3"

>>> c = 3.0

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IDLE Output

>>> a

3

>>> b

'3'

>>> c

3.0

Variables

• Different types of variables
• int
• str
• float
• Examples

>>> a = 3

>>> b = "3"

>>> c = 3.0

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Addition

>>> a + a

6

>>> c + c

6.0

>>> b + b

'33'

Variables

• Different types of variables
• int
• str
• float
• Examples

>>> a = 3

>>> b = "3"

>>> c = 3.0

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Guess the output

>>> a * a

9

>>> b * b

Traceback (most recent call last):

b * b

TypeError: can't multiply sequence by non-int of type 'str'

Preview to Casting

• How do we fix b * b?
• Use casting to change types

>>> d = int(b)

>>> d

3

>>> d * d

9

str(x), float(x), list(x), tuple(x), int(x), etc

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Guess the output

>>> a * a

9

>>> b * b

Traceback (most recent call last):

b * b

TypeError: can't multiply sequence by non-int of type 'str'

Conditions

>>> if True:

print("A")

else:

print("B")

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>>> if False:

print("A")

else:

print("B")

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>>> if True:

print("A")

elif True:

print("B")

else:

print("C")

Answers: A, B, A

Conditions Summary

• if statement required to use elif and else
• elif and else are optional
• elif only runs when the if or elif above was not run
• else runs if none of the if or elif has run

Operations

• +, -, *, /
• % (modulo)
• Returns int
• == and != (equality checks)
• Returns true or false

Modulo Examples��>>> 7 % 2

1

>>> -7 % 3

2

Equality + Conditions

>>> if 1 == 1:

print("nothing")

elif True:

print("interview")

>>> if 1 == “1”:

print("snowday")

elif True:

print("midterm")

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>>> if 1 == 2:

print("marks")

elif 1 == “1”:

print("passing")

Answers: nothing, midterm, [literally nothing]

Boolean Operations (Case sensitive!)

• Require two booleans (on left and right)
• and
• True and True == True
• True and False == False
• Both must be true
• or
• True or True == True
• True or False == True
• One must be true

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• not
• Requires just one boolean
• not True == False
• not False == True
• xor (extra)
• A != B
• True != False == True
• True != True == False

Boolean Operations

What do we do with a nested if?

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if handwashing:

if sleeping_well:

print("no corona")

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Try boolean operations

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if handwashing and sleeping_well:

print("no corona")

Loops - While

A = 0

if A < 2:

A = A + 1

if A < 2:

A = A + 1

if A < 2:

A = A + 1

...

A = 0

while A < 2:

A = A + 1

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Loops - While

• Why while loops

while True:

time.sleep(1)

if condition:

pass # Do something useful

Conditions (surprise review)

>>> if 2 < 3:

print("A")

elif 4 > 3:

print("B")

>>> if False:

print("hm")

elif "Python" > "JS":

print("not wrong")

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>>> if False:

print("cold")

elif False:

print("flu")

elif True:

print("coronavirus")

Answers: A, not wrong, coronavirus

Loops - For

>>> for i in range(3):

print(i)

0

1

2

Take a variable and change its value each time we enter the loop.

Functions

def count_down():

print(“3…”)

time.sleep(1)

print(“2…”)

time.sleep(1)

print(“1…”)

time.sleep(1)

print(“I’ve literally frozen the entire game while my bot runs”)

count_down()

print(“And done!”)

Functions

def count_down():

for i in range(3):

print(i)

time.sleep(1)

This isn’t the exact same yet!

How can we clean up the count_down function using a for loop?

Functions - Arguments

def count_down(delay):

for i in range(delay):

print(i)

time.sleep(1)

Still not the same but it works.

How can we clean up the count_down function using a for loop?

Can we make the count_down more customizable?

How about count_down(3) or count_down(5)?

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count_down(delay=5) is also valid!

Intermediate Python

Table of Contents�- Augmented assignment operators

- Casting

- Practice: Vertex formula

- return

- Lists, "append", "in"

- Dictionaries

- Multiple assignment

Augmented Assignment Operators

Replace, a = a + 3

With, a += 3

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Similarly

*=, -=, /=, %=

Augmented Assignment Operators

Replace, a = a + 3

With, a += 3

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Similarly

*=, -=, /=, %=

def get_negative(num):

result = 0

result -= num

print(result)

More Function Practice

Let’s make a function that gives the vertex of a quadratic.

f(x) = ax^2 + bx + c

The formula is x = -b / 2a.

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get_vertex(1, 2, 3)

e.g. x^2 + 2x + 3

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def get_vertex(a, b, c):

result = -b / (2 * a)

print(result)

More Casting Practice

What if we accidentally pass an str instead of a float?

get_vertex(“1”, “2”, “3”)

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Crashes!

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def get_vertex(a, b, c):

result = -float(b) / (2 * float(a))

print(result)

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Looks messier but still works.

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Returning to Functions

What if we want to store the result in a variable?

a = get_vertex(1, 2, 3)

Doesn’t crash but returns a special “None” value (like null).

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def get_vertex(a, b, c):

result = -b / (2 * a)

return result

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The function is evaluated and the returned variable becomes the value.

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Returning to Functions

a = get_vertex(1, 2, 3)

What value is printed?

What does “a” become?

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def get_vertex(a, b, c):

result = -b / (2 * a)

print(result)

return 1

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​

​

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Why return?

Helper functions

• Write a small program to take an argument and give a result
• Code re-use
• First step into modules

Intro to lists

>>> stones = []

>>> stones.append("time")

>>> stones.append("space")

>>> stones.append("reality")

>>> stones

['time', 'space', 'reality']

>>> stones[0]

'time'

>>> stones[1]

'space'

>>> stones[2]

'reality'

Intro to lists

>>> stones

['time', 'space', 'reality']

>>> del stones[0]

>>> stones

['space', 'reality']

>>> stones[3]

Traceback (most recent call last):

IndexError: list index out of range

>>> stones[-1]

'reality'

>>> stones[-2]

'space'

Why lists?

• Store a flexible amount of information in a single variable
• Players in a game
• Keeping track of items

>>> stones

['space', 'reality']

>>> "space" in stones

True

>>> "uw" in stones

False

Intro to Dictionaries

>>> classes = {}

>>> classes["ECON212"] = "PHYS"

>>> classes["PHYS124"] = "M3"

>>> classes

{'ECON212': 'PHYS', 'PHYS124': 'M3'}

>>> classes["ECON212"]

'PHYS'

>>> classes["PHYS467"]

Traceback (most recent call last):

classes["PHYS467"]

KeyError: 'PHYS467'

Intro to Dictionaries

>>> classes

{'ECON212': 'PHYS', 'PHYS124': 'M3'}

>>> del classes["ECON212"]

>>> classes

{'PHYS124': 'M3'}

>>> classes

{'PHYS124': 'M3'}

>>> "PHYS124" in classes

True

>>> "M3" in classes

False

Intro to Dictionaries

What kind of keys are possible?

Anything that’s hashable.

• int, str, float

>>> classes

{'PHYS124': 'M3'}

>>> classes[314] = "pi"

>>> classes

{'PHYS124': 'M3', 314: 'pi'}

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Can mix types of keys!

Multiple assignment

How do you swap two variables?

• a, b = b, a

And that is all.

def bad_pi():

return 3, 1, 4

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a, b, c = bad_pi()

print(a)

print(b)

print(c)

Guess the data structure

Guess the data type

country_status

Contains

"Alive":

"Filename":

"Health":

…

What data type is country_status?

"Alive":

"Filename":

"Health":

"ID": [A unique integer]

"Kills":

"Name":

"Nukes":

Intermediate Python 2

Table of Contents�- for loops revisited

- Nested data types

- Lists #2, "extend", "remove"

- break

- for else

- Sets

- Lists vs sets, performance

- Tuples

For loop

>>> stones

['space', 'reality', 'time']

>>> for i in stones:

print(i)

space

reality

time

The variable becomes each element in the list in sorted order.

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>>> for i in range(3):

print(i)

0

1

2

Nested data types

>>> nested = []

>>> nested.append([])

>>> nested.append(not True)

>>> nested

[[], False]

>>> nested[0]

[]

>>> nested[0].append("hidden")

>>> nested[0]

['hidden']

>>> nested[0][0]

'hidden'

>>> nested

[['hidden'], False]

More List Operations

>>> nested = {}

>>> nested["one"] = ["a", "b"]

>>> nested["two"] = ["c", "d"]

>>> nested

{'one': ['a', 'b'], 'two': ['c', 'd']}

>>> nested["one"].extend(nested["two"])

>>> nested

{'one': ['a', 'b', 'c', 'd'], 'two': ['c', 'd']}

>>> nested["one"].remove("b")

>>> nested

{'one': ['a', 'c', 'd'], 'two': ['c', 'd']}

Break

>>> nested

{'one': ['a', 'c', 'd'], 'two': ['c', 'd']}

>>> for i in nested["one"]:

print(i)

a

c

d

>>> for i in nested["one"]:

if i == "c":

break

print(i)

a

Break

>>> while True:

count += 1

print(count)

1

2

3…

Program never ends.

>>> while True:

count += 1

print(count)

if count > 3:

break

1… 2…. 3… 4.

and then we stop.

While-else, for-else?

while [code]:

[code]

break

else:

[code]

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Likely Python exclusive.

for [code]:

[code]

break

else:

[code]

Sets

Remember lists are ordered

>>> earth = ["a", "b"]

>>> L3 = ["b", "a"]

>>> earth == L3

False

>>> earth == ["a", "b"]

True

>>> rocket = ["r", "a", "c", "c", "o", "o", "n"]

>>> rocket

['r', 'a', 'c', 'c', 'o', 'o', 'n']

>>> set(rocket)

{'o', 'n', 'a', 'c', 'r'}

What happened?

Sets

Why sets?

• Removing duplicates
• list(set(x))
• Faster!
• in happens in constant rather than linear time compared to list
• List “in” searches the entire list
• Set “in” uses hashing

>>> mush = set(rocket)

>>> mush

{'o', 'n', 'a', 'c', 'r'}

>>> mush.remove("o")

>>> mush.add("hmm")

>>> mush

{'n', 'a', 'c', 'hmm', 'r'}

Tuples

>>> earth = ["rocks", "ice"]

>>> mars = tuple(earth)

>>> mars

('rocks', 'ice')

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Tuples use ( ) instead of [ ].

>>> mars.append("people")

Traceback (most recent call last):

mars.append("people")

AttributeError: 'tuple' object has no attribute 'append'

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People don’t go to Mars. Tuples are immutable.

Tuples

Why tuples?

• Immutable
• Safer
• Faster
• Not as fast as sets
• Stores duplicates and order

>>> mars + mars

('rocks', 'ice', 'rocks', 'ice')

>>> earth + earth

['rocks', 'ice', 'rocks', 'ice']

Why does this work?

We can still build new tuples (and lists) from old ones.

Back to the Game

Running the Game

• Game.py
• The text version of the game which you can run to watch bots compete
• Graphical.py
• The graphical version which needs Pygame (strongly recommended)
• Difficult to set up
• Batch.py
• Runs thousands of games and shows the winner
• Uses multiple cores!

API

• We use dictionaries containing keys to various data types

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• country_status describes the statistics of your own country (health, your ID, your number of nukes)
• world_state describes everything else
• Information on each country, all previous events (such as weapons fired), and a set of living players

Bots Directory

• Each Python file here contains a single class representing a bot
• More on OOP next week!

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• API.txt contains information on the API
• Will be finalized by Lesson 2

Sample Bot

• Here we see an example of a library being used in Python
• random.choice is used to pick a random element from an array
• random.randint is used to pick a random integer (weapons are integers)

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• country_status and world_state are arguments that describe the situation
• We return a dictionary with two arguments to represent our action

Next Time

• Learn about object-oriented programming
• Build a bot together in class
• Make sure you install Python and Pygame for next week
• Ask for help on Slack since the start is the hardest part
• Make sure you can open py files with IDLE (or an IDE of your choice)

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Good luck with interviews / midterms. Ask me anything.