COMP1021_HKUST@Spring2013

7/23/2019 COMP1021_HKUST@Spring2013

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COMP1021: PYTHON SYNTAX BOX

ContentsBasic Syntax .................................................................................................................................................................................................................................................. 2

Modular programming ................................................................................................................................................................................................................................ 4

Advanced Syntax ........................................................................................................................................................................................................................................ 5

PythonOptimisation .................................................................................................................................................................................................................................. 7

PythonFile Handling.................................................................................................................................................................................................................................. 7

Control Statements ...................................................................................................................................................................................................................................... 8

Turtle FunctionsImport turtle .................................................................................................................................................................................................................... 8Turtle FunctionsEvent Handling ............................................................................................................................................................................................................. 11

Time libraryManaging python time ...................................................................................................................................................................................................... 12

Random LibraryImport random ............................................................................................................................................................................................................ 12

(External Library) Music Functionsimport pygame.midi..................................................................................................................................................................... 12

Initialisation and Closing ........................................................................................................................................................................................................................ 12

L-System (Start value, Replacement rules, ) ........................................................................................................................................................................................ 13

Appendix-Instrument ................................................................................................................................................................................................................................. 14


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Basic SyntaxI/O

Functions print(, end=)Output a string on the screen (Default: end=eoln)

end = End the line with escape char or other (e.g. eoln, null)

= input()Prompt a string Input a string

Conversion

Functions int()Convert into str()Convert any into

ord()Return the ASCII code of the char in decimal number system

chr()Return the char with specified ordinal value

Arithmetic

Functions round(, )

return Round the into float number with If not set: Convert into integerIf = 0, data type remains unchanged

round(, )

return Does nothing with even with greater than 0

max ()Return the max value

max ()Return the min value

If = : Ordinal value (e.g. ord(B) > ord(A)

If = : max() = max(.keys()),

max(.items()) .keys() Return ,

Comments

Comments in paragraph length

# Comments on a single line

Operators+= (a = a + )

Shorthand Assignment ( = )

// (Division integer), % (Mod)Truncated:

(e.g.) 8.5 % 2 = 0.5 (Modulus operator: No conversion)

==, !=, >=, , >> 2.0000000000000001 == 2True>>> 2.000000000000001 == 2False>>> type(2/2)>>> type(2//2)


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Precedence(dec)

() ** - * / % // + - < > != == not and or

Bracket Power Unary operator Multiple operator Arithmetic operator Comparison operator Logical operator

True/ FalseTrue or || > 0 (Non-zero) False or = 0

Break andContinue

Statement

breakCurrent Loop Structure Current Loop

Loop Structure

continueCurrent Iteration

Next Iteration iterationcontinue Statement of

Current Loop Structure

Swapping, , = , ,

Assign the nth value of the list on the right to the nth item of the list on the left ( )

s can be of different types

= [ : : -1]As = -1, not specified = -1, not specified =

Error

Reporting import sys #Recognise System Error

try:

except :

else:

Try Process Exception

cases Programme

except Error:

ValueError Datatype Error I/O error

Reminder Quotes in Python can be (Double quote) or (Single quote)

They must be in pair

All { (Big bracket) or ; (Semi-colon)

Replaced by indentation in Python

Indentation

Indentation takes over any structural brackets Indentation wrong Syntax Error

RangeListStep

start or endValuePositive Step: start = 0 , end = len()

Negative Step: start = ord(last item), end =Pressing Kill the program in a friendly way


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Modular programmingDefining

functions def (,, ):

Define your own function, parameters ProcedureDefine

return Return a value and end Function

Variables: Function Variables

localized

Global Variable vs. Local variable

Global vs.

Local global can be used outside modules

= Local variable is limited to functions

Class

and

objects

class :Define the Class Name.

All included function can be called by .

def __init__ (self, , ):Define the initial parameters that new class objects have to

provide

1st self

def (self, , )Define Function 1st self

Class Functions __init__ variables

self. = variables self. Call

(@Class)

= (,, )

Define new object as a member of the class

Instance Objects (Attribute Reference) (Class obj.) Method Objects ( ) Property ( )


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Advanced SyntaxRange

(List)

(Array)

range(, ,)

A temporary list consisting integers from to

Step: +1 +

list(range(0, 3)) == 0, 1, 23 - 1

range(, ,

)Range from large to small, with negative step

[int_h]

[int_l-1]

range(, )Range from to - 1

(e.g. of ): funny[-1:2:-1] == yn

funny[-1:2:] == funny[2:-1:] == nn

[, , ]Self-defined set starting with item 0 (ordinal value == 0)

character == []e.g. p == ape[1]

String is a list of characters

List and tuple= [, ,]

Items can be in different types

Enclosed by a pair of square brackets

Can be modified

= (, ,)Items can be in different types

Enclosed by a pair of normal brackets

Cannot be modified (Constant list)

positive ordinal value: from 0 from left

[0]: Leftmost item

negative ordinal value: from -1 from right

[-1]: Rightmost item

List

(Functions) .insert(,

)

Insert an into the of the

.remove ()Remove the from String

.append()Append an to the

[::]

:

remains unchanged

Output an modified with specified features

.index()Return the position of the in the list

= .pop()Remove the last item in the list and contain with


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Return: is not in the list Default = len() - 1

Dictionary= List type with

(not onlyautomatically

assigned

integer)

(When calling

them, the order

of all items arerearranged)

= { : ,

: , }[] =

for key, value in .items():

print(key, value)Print out () line by line

.items()dict_items([(, ), (,), ])

.values()dict_values([, , ])

del []Delete the item (key and value) with

del

: Can be used for any :

Remove its memory location

Assessing Items

.keys()dict_keys([, , , ])

Nested List

(record)

(3D structure)

[x_axis][y_axis][z_axis]

Excel Database Record

2D Structure Surface Datum 3D Structure Cube Datum

StringTuple List

Tuple

char

len()Return the length of the list = ord([-1]) + 1

[::]

(e.g.) funny[1:3] == un(Not unn )

Default: == 0, == len(string_type>)

char

+ Text concatenation:

(e.g.) fun + kid == funkid

* copies of :

(e.g.) fun * 3 == funfunfun


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PythonOptimisationTurtle library

turtle.undo()Undo the previous turtle process

turtle.setundobuffer() can be None : undo buffer

Improt syssys.getrecursionlimit()

Return the size of the stack for python

sys.setrecursionlimit()

Set the size of the stack to Stack

PythonFile HandlingEscape

characters \tTab character

\nNew line character

Read &

Write files = open(, r)r: Open the file as Read-Only Mode

= open(, )w: Open the file as Write Mode

wt: Open the file using write + text modeWhenever the file is opened this way, everything in the file is cleared.

.write()Write the to the

.close()Free up System resources

: Will be in _io.TextIOWrapper class (not str class)

for line in : statement []

.readlines() Lines items

Remove

char

(String)

Default = space character

.strip

.strip()

.lstrip()

.rstrip())

String

list = .split()

Slice at all positions of Create a


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Control StatementsIf Statement

if : If condition if true, run the process

elif :

else: If Statemtn If else if else

While Loop while : Condition == True, break or condition == False

For Loopfor in :

_ variable (e.g.) for _ in range(10):Integer or character = List items, List ordinal item

Turtle FunctionsImport turtle

(usr_turtle:User-defined turtle)(turtle: System turtle, with all attributes accessible)Basic

Import turtleImport the turtle library for use

usr_turtle.reset()Initialise the turtle on the screen

turtle.done()Stop the turtle from further intruption

Movementusr_turtle.goto(, )

usr_turtle.setpos(, )Initial position (middle) = 0, 0

Move the turtle to a specific coordinateon the screen

usr_turtle.forward()Move the turtle ahead of its present direction

usr_turtle.backward()Move the turtle back to the direction if its

tail

usr_turtle.left()Rotate the turtle leftward by

degrees

usr_turtle.right()Rotate the turtle rightward by

degrees

usr_turtle.speed()0: Instant ; 1: Slow < 10: Fast

Drawingusr_turtle.width()

usr_turtle.up() usr_turtle.down()Put down the turtle Draw when moving


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Set the width of lines drawn by turtle in

pixels

Take up the turtle Not drawing when

moving

turtle.begin_fill()

turtle.end_fill()

Fill the shape drawn by the turtle with fillcolour

usr_turtle.fillcolor()Set fill colour in colour

usr_turtle.fillcolor()Return the present fill color

usr_turtle.color()Set colour for both fill colour and pen

colour

usr_turtle.color(, )Set colour for 2 types of colours

usr_turtle.color()pen colour and fill colour

usr_turtle.undo()Undo the previous step as stored in the turtle stack

usr_turtle.dot(,

)Define the dot size and drop a dot

usr_turtle.write(, align=,

font = (, )Write on with the 1st char of on turtle

Geometryusr_turtle.circle(, )

Draw a circle with radius specified and centre at from the left of the usr_turtle.: +ve: Centre on the left; -ve: Centre on the right

Counterclockwise ( > 0)

Draw with . A complete circle is 360 .

Turtle Screen

Control turtle.update()Update the turtle screenTo be used after usr_turtle.tracer(False)

usr_turtle.clear()Clear the drawings from , not

other turtles

usr_turtle.hideturtle()

usr_turtle.showturtle()Turtle

turtle.tracer ()usr_turtle.tracer(False):

usr_turtle.tracer(True):

turtle.colormode(1.0)1.0 : Float type, 255 : Integer Type

Set colour attributes into 0.0 ~ 1.0

format

turtle.colormode(255)Set colour attributes into 0 ~ 255 format

Turtle Color attribute Color

name Assign

turtle.bgcolor()Set the background colour of turtle screen

turtle.bgpic()Set the background image to the


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Turtle system

settings turtle.mode(world) /

turtle.mode(standard)Use the self-defined world orstandard for turtle

turtle.setup(width=,

height=)Setup the turtle screen size. For , it means the % of the OS screen

occupied by this turtle screen

turtle.setworldcoordinates(, , , )Define the coordinates of the new world

Recurringfunctions turtle.ontimer(, )

Recur the function per infinitely

Define new

turtles usr_turtle.shape()

Predefined shapes:Arrow, Turtle, Circle,

Square, Triangle, Classic

turtle.addshape()

User defined shape can be used only afteraddshape

=turtle.Turtle()

Define new turtle with name =

usr_turtle.shapesize(, )

Define the turtle size with heights and width

= []

.append(turtle.Turtle())

Make good use of append(), instead of predefining the amount of l ist items (e.g.)turtles[i] = usr_turtle.Turtle()


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Turtle FunctionsEvent Handlingusr_turtle.on

(Mouse

movement)

No brackets

after

(i.e. (),

usr_turtle.onclick ()Run the when the turtle in clicked by

mouse

turtle.ontimer (,)

Run the according to the timer

usr_turtle.ondrag ()Run the when users drags the turtle

usr_turtle.ondrag (usr_turtle.goto)Move the turtle according to your mouse movementFor instant update of the position, need usr_turtle.tracer(False) +

usr_turtle.update()

usr_turtle.xcor()Return the x coordinate of the turtle

usr_turtle.ycor()Return the y coordinate of the turtle

usr_turtle.on

(KB, MOUSE,

clicking)

turtle.onscreenclick ()Run the when the screen is clicked by

mouse

turtle.onkeyrelease(,)

Run the Run the when the is released

turtle.onkeypress (,

)Run the when the is pressed

turtle.listen()Keep listening any keyboard event

Run this like usr_turtle.done(), must-have + Program

All turtle.on + Related to : Requires def (null_x, null_y)


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Time libraryManaging python timeTime halt

time.sleep()Wait for seconds to next statement

Condition: Used for delay in pressing/ leaving on/from a note

Smooth

Python uptimetime.clock()

Return the uptime of python, in second starting from 0

time.clock()>>> 6.182458438486231

Program

Random LibraryImport randomRandomise data

random.randrange(, )Generate integers between int_l and int_h

random.randint(, ))Randomise an integer between (Inclusive) integer_l and integer_h

Shuffling listrandom.shuffle()

Randomise the orders of all items

random.uniform(


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Note On/

Off output.note_on(, , )Drum Channel

output.note_off(, ,)

Pitch,

Volume,Channel Pitch in range(128)Note in range(24, 108) Channel inrange(16)

Default 0

Drum 9

Volume in range(128)127:

(For

== 0)

output.set_intstrument()Instrument code in range (0, 127)

L-System (Start value, Replacement rules, )Explanation

Variables = { F }Variables that have replacement rules

F: Usually represents forward

Constant = {+, - }Constant that have predefined command+: Turn left, -: Turn right

Starting string = FX+FInitial string from further replacement

Rules = F FF-F-F++Rules to replace the command char in string

Angle = 90Define the angle for the turtle to be rotated (+, -)

Iteration = 4Number of iterations to be run


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Appendix-Instrument0 Acoustic Grand

Piano

8 Celesta 16 Drawbar Organ 24 Acoustic Guitar

(nylon)

32 Acoustic Bass 40 Violin

1 Bright Acoustic

Piano

9 Glockenspiel 17 Percussive

Organ

25 Acoustic Guitar

(steel)

33 Electric Bass

(finger)

41 Viola

2 Electric Grand

Piano

10 Music Box 18 Rock Organ 26 Electric Guitar (jazz) 34 Electric Bass (pick) 42 Cello

3 Honky-tonk Piano 11 Vibraphone 19 Church Organ 27 Electric Guitar

(clean)

35 Fretless Bass 43 Contrabass

4 Electric Piano 1 12 Marimba 20 Reed Organ 28 Electric Guitar

(muted)

36 Slap Bass 1 44 Tremolo Strings

5 Electric Piano 2 13 Xylophone 21 Accordion 29 Overdriven Guitar 37 Slap Bass 2 45 Pizzicato Strings

6 Harpsichord 14 Tubular Bells 22 Harmonica 30 Distortion Guitar 38 Synth Bass 1 46 Orchestral Harp

7 Clavinet 15 Dulcimer 23 Tango

Accordion

31 Guitar Harmonics 39 Synth Bass 2 47 Timpani

48 String Ensemble 1 56 Trumpet 64 Soprano Sax 72 Piccolo 80 Lead 1 (square) 88 Pad 1 (new

age)

49 String Ensemble 2 57 Trombone 65 Alto Sax 73 Flute 81 Lead 2 (sawtooth) 89 Pad 2 (warm)50 Synth Strings 1 58 Tuba 66 Tenor Sax 74 Recorder 82 Lead 3 (calliope) 90 Pad 3

(polysynth)

51 Synth Strings 2 59 Muted

Trumpet

67 Baritone Sax 75 Pan Flute 83 Lead 4 (chiff) 91 Pad 4 (choir)

52 Choir Aahs 60 French Horn 68 Oboe 76 Blown Bottle 84 Lead 5 (charang) 92 Pad 5 (bowed)

53 Voice Oohs 61 Brass Section 69 English Horn 77 Shakuhachi 85 Lead 6 (voice) 93 Pad 6 (metallic)

54 Synth Choir 62 Synth Brass 1 70 Bassoon 78 Whistle 86 Lead 7 (fifths) 94 Pad 7 (halo)

55 Orchestra Hit 63 Synth Brass 2 71 Clarinet 79 Ocarina 87 Lead 8 (bass +lead)

95 Pad 8 (sweep)

96 FX 1 (rain) 104 Sitar 112 Tinkle Bell 120 Guitar Fret Noise

97 FX 2 (soundtrack) 105 Banjo 113 Agogo 121 Breath Noise98 FX 3 (crystal) 106 Shamisen 114 Steel Drums 122 Seashore

99 FX 4 (atmosphere) 107 Koto 115 Woodblock 123 Bird Tweet

100 FX 5 (brightness) 108 Kalimba 116 Taiko Drum 124 Telephone Ring

101 FX 6 (goblins) 109 Bagpipe 117 Melodic Tom 125 Helicopter

102 FX 7 (echoes) 110 Fiddle 118 Synth Drum 126 Applause

103 FX 8 (sci-fi) 111 Shanai 119 Reverse Cymbal 127 Gunshot

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