2010 12 11 python workshop

8/8/2019 2010 12 11 Python Workshop

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Python

Hlne Martin

Puget Sound CSTA

December 11th, 2010

Special thanks to Marty Stepp for some formatting and content


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Hlne Martin

Bachelors in CS from UW

Career and Technical Ed through South Seattle

Teach at comprehensive public high school

Five periods of computer science

- 2x Exploring Computer Science- 2x AP Computer Science- 1x AP Computer Science (Experienced)

http://garfieldcs.com
http://garfieldcs.com/http://garfieldcs.com/http://garfieldcs.com/


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Why Teach Python?

Light-weight syntax

Multi-paradigm (procedural, OO, functional)

Lots of great libraries- turtle graphics- pygame- scipy- myro (workshop last spring)

InterpretedPermissive

Used increasingly in college courses, web applications


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Why Not Teach Python?

Permissive

Dynamically typed (values have types, but not

variables)

Too many ways to skin a single cat!

Not used much in corporate world

- Though YouTube, Google, Yahoo!, NASA make some use of it- Primarily for internal tools (think Perl)


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Creative Computing

Semester-long high school course

Only pre-requisite is algebra 1

Topic progression:

- Basic syntax with turtle graphics (iteration, variables,conditionals)

- Functions (abstraction)

- Compound data: strings and lists- Programming robots- Object-oriented basics- Games with pyGame


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Getting Python

Free at http://python.org

Generally pre-installed on OS X or Linux

Includes IDLE, a basic IDE
http://python.org/http://python.org/


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Interacting With IDLE

Programs saved with .py extensions

Commands interpreted straight in shell

Students can get confused about the two!!


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Procedural Turtle Graphics

Long tradition started by Logo

Drawing shapes gives instant feedback

Students get used to syntax, algorithms

Note: students often savefiles as turtle.py - remind

them not to do that!


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Available functions

http://docs.python.org/library/turtle.html

- forward() | fd()- backward() | bk() | back()- right() | rt()- left() | lt()- goto() | setpos() | setposition()- stamp()- speed()- pendown() | pd() | down()- penup()| pu() | up()

- pensize() | width()- color()- begin_fill()- end_fill()- clear()

- write()- showturtle() | st()- hideturtle() | ht()- shape()- register_shape() | addshape()
http://docs.python.org/library/turtle.html#turtle.clearhttp://docs.python.org/library/turtle.html#turtle.clearhttp://docs.python.org/library/turtle.html#turtle.clearhttp://docs.python.org/library/turtle.html#turtle.end_fillhttp://docs.python.org/library/turtle.html#turtle.begin_fillhttp://docs.python.org/library/turtle.html#turtle.colorhttp://docs.python.org/library/turtle.html#turtle.pendownhttp://docs.python.org/library/turtle.html#turtle.pendownhttp://docs.python.org/library/turtle.html#turtle.pendownhttp://docs.python.org/library/turtle.html#turtle.pendownhttp://docs.python.org/library/turtle.html#turtle.pendownhttp://docs.python.org/library/turtle.html#turtle.pdhttp://docs.python.org/library/turtle.html#turtle.speedhttp://docs.python.org/library/turtle.html#turtle.speedhttp://docs.python.org/library/turtle.html#turtle.speedhttp://docs.python.org/library/turtle.html#turtle.speedhttp://docs.python.org/library/turtle.html#turtle.stamphttp://docs.python.org/library/turtle.html#turtle.stamphttp://docs.python.org/library/turtle.html#turtle.stamphttp://docs.python.org/library/turtle.html#turtle.lefthttp://docs.python.org/library/turtle.html#turtle.righthttp://docs.python.org/library/turtle.html#turtle.clearhttp://docs.python.org/library/turtle.html#turtle.clearhttp://docs.python.org/library/turtle.html#turtle.clearhttp://docs.python.org/library/turtle.html#turtle.begin_fillhttp://docs.python.org/library/turtle.html#turtle.begin_fillhttp://docs.python.org/library/turtle.html#turtle.begin_fillhttp://docs.python.org/library/turtle.html#turtle.addshapehttp://docs.python.org/library/turtle.html#turtle.addshapehttp://docs.python.org/library/turtle.html#turtle.register_shapehttp://docs.python.org/library/turtle.html#turtle.register_shapehttp://docs.python.org/c-api/buffer.html#shapehttp://docs.python.org/c-api/buffer.html#shapehttp://docs.python.org/library/turtle.html#turtle.hthttp://docs.python.org/library/turtle.html#turtle.hthttp://docs.python.org/library/turtle.html#turtle.hideturtlehttp://docs.python.org/library/turtle.html#turtle.hideturtlehttp://docs.python.org/library/turtle.html#turtle.sthttp://docs.python.org/library/turtle.html#turtle.sthttp://docs.python.org/library/turtle.html#turtle.showturtlehttp://docs.python.org/library/turtle.html#turtle.showturtlehttp://docs.python.org/library/turtle.html#turtle.writehttp://docs.python.org/library/turtle.html#turtle.writehttp://docs.python.org/library/turtle.html#turtle.clearhttp://docs.python.org/library/turtle.html#turtle.clearhttp://docs.python.org/library/turtle.html#turtle.end_fillhttp://docs.python.org/library/turtle.html#turtle.end_fillhttp://docs.python.org/library/turtle.html#turtle.begin_fillhttp://docs.python.org/library/turtle.html#turtle.begin_fillhttp://docs.python.org/library/turtle.html#turtle.colorhttp://docs.python.org/library/turtle.html#turtle.colorhttp://docs.python.org/library/turtle.html#turtle.widthhttp://docs.python.org/library/turtle.html#turtle.widthhttp://docs.python.org/library/turtle.html#turtle.pensizehttp://docs.python.org/library/turtle.html#turtle.pensizehttp://docs.python.org/library/turtle.html#turtle.pensizehttp://docs.python.org/library/turtle.html#turtle.pensizehttp://docs.python.org/library/turtle.html#turtle.uphttp://docs.python.org/library/turtle.html#turtle.uphttp://docs.python.org/library/turtle.html#turtle.puhttp://docs.python.org/library/turtle.html#turtle.puhttp://docs.python.org/library/turtle.html#turtle.penuphttp://docs.python.org/library/turtle.html#turtle.penuphttp://docs.python.org/library/turtle.html#turtle.downhttp://docs.python.org/library/turtle.html#turtle.downhttp://docs.python.org/library/turtle.html#turtle.pdhttp://docs.python.org/library/turtle.html#turtle.pdhttp://docs.python.org/library/turtle.html#turtle.pendownhttp://docs.python.org/library/turtle.html#turtle.pendownhttp://docs.python.org/library/turtle.html#turtle.speedhttp://docs.python.org/library/turtle.html#turtle.speedhttp://docs.python.org/library/turtle.html#turtle.stamphttp://docs.python.org/library/turtle.html#turtle.stamphttp://docs.python.org/library/turtle.html#turtle.setpositionhttp://docs.python.org/library/turtle.html#turtle.setpositionhttp://docs.python.org/library/turtle.html#turtle.setposhttp://docs.python.org/library/turtle.html#turtle.setposhttp://docs.python.org/library/turtle.html#turtle.gotohttp://docs.python.org/library/turtle.html#turtle.gotohttp://docs.python.org/library/turtle.html#turtle.lthttp://docs.python.org/library/turtle.html#turtle.lthttp://docs.python.org/library/turtle.html#turtle.lefthttp://docs.python.org/library/turtle.html#turtle.lefthttp://docs.python.org/library/turtle.html#turtle.rthttp://docs.python.org/library/turtle.html#turtle.rthttp://docs.python.org/library/turtle.html#turtle.righthttp://docs.python.org/library/turtle.html#turtle.righthttp://docs.python.org/library/turtle.html#turtle.backhttp://docs.python.org/library/turtle.html#turtle.backhttp://docs.python.org/library/turtle.html#turtle.bkhttp://docs.python.org/library/turtle.html#turtle.bkhttp://docs.python.org/library/turtle.html#turtle.backwardhttp://docs.python.org/library/turtle.html#turtle.backwardhttp://docs.python.org/library/turtle.html#turtle.fdhttp://docs.python.org/library/turtle.html#turtle.fdhttp://docs.python.org/library/turtle.html#turtle.forwardhttp://docs.python.org/library/turtle.html#turtle.forwardhttp://docs.python.org/library/turtle.htmlhttp://docs.python.org/library/turtle.htmlhttp://docs.python.org/library/turtle.html


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Geometry exercises

Reasoning about repetition

Breaking down a problem into steps

http://neoparaiso.com/logo/ejercicios-de-

geometria.html
http://neoparaiso.com/logo/ejercicios-de-geometria.htmlhttp://neoparaiso.com/logo/ejercicios-de-geometria.htmlhttp://neoparaiso.com/logo/ejercicios-de-geometria.htmlhttp://neoparaiso.com/logo/ejercicios-de-geometria.html


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Iteration

Definite loop

Indefinite loop

for loop structure

1

234

for i in range():

print("Hi") # not repeated

while loop strcture

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while():

print("Hi") # not repeated


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Functions

Definition

Calling

- Students often forget to use parentheses when calling

The def keyword is used for defining functions

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def hello(, ...):

print("Hello, world!")

hello()hello()


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Print Function

Simple! (no System.out.yuck)

Can be called with parameters of different types

Concatenation shows ugliness of dynamic types

Print can dis la different t es

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4

print("Hello, world!")

print()print(25)

print("You have " + str(dollars) + " dollars")


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Python Operations

Arithmetic:

- ** (exponent)- * (multiplication) / (division) % (modulus)- + (addition) - (subtraction)

Boolean

- == != < >=- not

- and or

Common Types

- int, float, bool, str


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Conditionals

Co ditional structure

123456

if(): elif():

else:


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User input

Us r input

123456

>>> name = raw_input("Your name?")Your name? Bonnie

>>> name'Bonnie'

User input - numbers123456

>>> age = int(raw_input("Your age?"))Your age? 15

>>> age15


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External Libraries

Import modules to get access to more functions

Usi g random numbers

1234

from random import *

die1 = randint(1, 6)die2 = randint(1, 6)


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Iterating over strings

Can access length using len() function

Can use for loop to examine each character

Looping over a string

123456

78910

>>> for c in "PSCSTA":print c

PS

CSTA


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String methods

str.capitalize()

str.endswith(suffix)

str.find(sub)

str.isdigit()

str.join(iterable)

str.lower()

str.replace(old, new)str.split([sep])str.startswith(prefix)

str.strip()

str.title()

str.upper()

http://docs.python.org/library/stdtypes.html#string-methods
http://docs.python.org/library/stdtypes.html#string-methodshttp://docs.python.org/library/stdtypes.html#string-methodshttp://docs.python.org/library/stdtypes.html#string-methodshttp://docs.python.org/library/stdtypes.html#string-methods


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Lists

Lists

1234

5678910

111213

14

1516171819

>>> nums = [2, 4, 6, 8]>>> for num in nums:

print num2468>>> nums.reverse()>>> nums[8, 6, 4, 2]>>> nums.append(10)>>> nums[8, 6, 4, 2, 10]>>> nums.sort()>>> nums[2, 4, 6, 8, 10]>>> nums[len(nums) - 2]8


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Your turn

Write a pig latin programPhrase to translate? What a lovely day it is

hatWAY AAY ovelyLAY ayDAY tIAY sIAY

Simple: move the first letter to the back and add

AY. Capitalize the last three letters

More complex: if the word starts with a vowel,

just add ay. Move first consonant cluster.- trash -> ashTRAY- ashtray -> ashtrayAY- Write a boolean function is_vowel


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File reading

File reading

1234

5

>>> f = open("my_file")

>>> for line in f:...

Longe t line in a file

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def longest_line(f):maxline = ""for line in f:

if len(line) > len(maxline):maxline = line

return maxline


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File projects


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Dictionaries

Write a program to count the frequency of words in the Washington state

programming framework.

>>> import operator>>> sorted(words.iteritems(), key=operator.itemgetter(1))

L ngest line in a file

123

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6789

>>> birth_years = {"Bob":1983, "Mary":1955, "Joe":2000}>>> birth_years["Bob"]1983>>> birth_years.keys()['Bob', 'Mary', 'Joe']>>> birth_years.values()[1983, 1955, 2000]>>> birth_years.has_key("Andy")False


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Classes

No encapsulation

Explicit use of self

__what?!__

point.py

123

4

56789

1011121314

from math import *

class Point:def __init__(self, x, y):

self.x = xself.y = y

def distance(self, other):dx = self.x - other.xdy = self.y - other.yreturn sqrt(dx * dx + dy * dy)

def __str__(self):return "(" + str(self.x) + ", " + str(self.y) + ")"


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Python Resources

http://python.org/

http://diveintopython.org

http://openbookproject.net//thinkCSpy/
http://openbookproject.net//thinkCSpy/http://openbookproject.net//thinkCSpy/http://diveintopython.org/http://diveintopython.org/http://python.org/http://python.org/


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Scribblers

2010 12 11 python workshop

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