Phần 26 KHÓA ĐÀO TẠO TÍNH TOÁN ỔN ĐỊNH VÀ ỨNG DỤNG TRÊN PHẦN MỀM PSSE CHO KỸ SƯ HỆ THỐNG ĐIỆN (Ngôn ngữ lập trình Python và ứng dụng trên Phần mềm PSSE)

TRANSMISSION &
DISTRIBUTION
A Division of Global Power
POWER SYSTEM STABILITY CALCULATION TRAINING
D13
It d ti t Pth
D
ay
13
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I
n
t
ro
d
uc
ti
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o
P
y
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on
December 4, 2013Prepared by: Mohamed El Chehaly
eBook for You
OUTLINE
2
OUTLINE
• Basic Syntax
• Variables

• Control Flow Tools
• Built-In Functions and Methods
• User-Defined Functions
• Files and Directories
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3
BASIC SYNTAX
BASIC

SYNTAX
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Introduction
4
BASIC SYNTAX
Introduction
 Easy to learn, powerful programming tool

Efficient high
level data structures

Efficient

high
-
level

data

structures
 Simple but effective approach to object-

oriented programming
oriented

programming
 Programs in Python much shorter than
equivalent C C++ or Java programs:
equivalent

C
,
C++

or

Java

programs:
 Complex operations can be expressed in a single
statement
 Statement grouping is done by indentation instead
of beginning and ending brackets

Nibl tdlti

N
o var
i
a
bl
e or argumen

t

d
ec
l
ara
ti
ons are
necessary
eBook for You
Introduction
5
BASIC SYNTAX
Introduction
 Interpreted: It is processed at runtime by
the interpreter and you do not need to
the

interpreter

and

you

do

not

need

to

compile your program before executing it

Interactive:
You can actually sit at a

Interactive:
You

can

actually

sit

at

a

Python prompt and interact with the
inter
p
reter directl
y
py
 Object-oriented: Python supports style or
technique of programming that
encapsulates code within Objects
 Beginner’s language: Great language for

beginner programmers
eBook for You
Python Basic Syntax
6
BASIC SYNTAX
Python

Basic

Syntax
 Interactive mode programming

Open IDLE (Python GUI)

Open

IDLE

(Python

GUI)
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Python Basic Syntax
7
BASIC SYNTAX
Python

Basic

Syntax

 Interactive mode programming

Write the following

Write

the

following

print “Hello; Python!”
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Python Basic Syntax
8
BASIC SYNTAX
Python

Basic

Syntax
 Script mode programming

Open new window

Open

new

window

eBook for You
Python Basic Syntax
9
BASIC SYNTAX
Python

Basic

Syntax
 Script mode programming

Write the following

Write

the

following

print “Hello, Python!”
eBook for You
Python Basic Syntax
10
BASIC SYNTAX
Python

Basic

Syntax
 Script mode programming


Save as “Hello Python py”

Save

as

“Hello

Python
.
py”

 Run module
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Python Identifiers
11
BASIC SYNTAX
Python

Identifiers
 Name used to identify

Variable

Variable
 Function

Class


Class
 Module
 Other ob
j
ects
j
 Starts with
 Letter A to Z
 Letter a to z
 Underscore
 No punctuation characters such as @,$,%
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Python Identifiers
12
BASIC SYNTAX
Python

Identifiers
 Python is case sensitive (name and Name)

CtifPth

C
onven
ti
on
f
or
P
y

th
on
 Class names start with an uppercase letter

Starting an identifier with a single leading

Starting

an

identifier

with

a

single

leading

underscore “_” indicates that the identifier is
private
 Starting an identifier with two leading underscores
“__”indicates a strongly private identifier

If the identifier also ends with two trailing

If

the

identifier

also

ends

with

two

trailing

underscores, the identifier is a language-defined
special name
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Python Identifiers
13
BASIC SYNTAX
Python

Identifiers
 Reserved words
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Lines and Indentation
14
BASIC SYNTAX
Lines

and

Indentation
 Blocks of code for class and function
definitions or flow control denoted by line
definitions

or

flow

control

denoted

by

line

indentation

No use of braces
“
{}
”

No

use

of

braces

{

}
 Test the following code

Test the following code

Test

the

following

code
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Multi
Line Statements
15
BASIC SYNTAX
Multi
-
Line

Statements
 Statements in Python typically end with a
new line
 Continuation on next line allowed with “\”

 Statements contained within [ ], { } and ( )
do not need to use the line continuation
ht
c
h
arac
t
er
eBook for You
Quotation in Python
16
BASIC SYNTAX
Quotation

in

Python
 Python accepts single (‘), double (“) and
triple (‘’’ or “””) quotes to denote string
 The same types of quote should start and
dth ti
en
d

th
e s
t
r
i
ng

 The triple quotes can be used to span the
t i lti l li
s
t
r
i
ng across mu
lti
p
l
e
li
nes
eBook for You
Comments in Python
17
BASIC SYNTAX
Comments

in

Python

 A hash sign “#” that is not inside a string
lateral begins a comment
 All characters after the # and up to the
hilli d tfth t
p
h
ys

i
ca
l

li
ne en
d
are par
t
o
f

th
e commen
t
 A line can be commented by ALT+3 and
tdb ALT+4
uncommen
t
e
d

b
y
ALT+4
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Waiting for the User
18
BASIC SYNTAX
Waiting

for

the

User
 The following line of the program displays
th t “P th t k t i t ”
th
e promp
t

“P
ress
th
e en
t
er
k
ey
t
o ex
i
s
t
.
”

 The program will wait for the user to
press the Enter key

press

the

Enter

key
 Here “\n\n” are being used to create two
new lines before displaying the actual line
new

lines

before

displaying

the

actual

line
 This is a nice trick to keep a console
window open until the user is done with an
window

open

until

the

user

is

done

with

an

application
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19
VARIABLES
VARIABLES
eBook for You
Standard Data Type
20
VARIABLES
Standard

Data

Type
 Numbers
 Strin
g
g


List

List

Tuple

Tuple

Dictionary

Dictionary
eBook for You
Assigning Values to Variables
21
VARIABLES
Assigning

Values

to

Variables
 Python variables do not have to be
explicitly declared
 The declaration happens automatically
when you assign a value to a variable
eBook for You
Numbers
22

VARIABLES
Numbers
 Python supports four different numerical
types
types
 int: signed integers
 lon
g
: lon
g
inte
g
ers
(
can also be re
p
resented in
g
gg( p
octal and hexadecimal)
 float: floating point real values
 complex: complex numbers
 Numbers with different base can be
represented
represented
 Binary: start with 0B or 0b

Octal: start with 0O or 0o

Octal:

start

with

0O

or

0o
 Hexadecimal: start with 0x or 0X
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Numbers
23
VARIABLES
Numbers
 Examples
 Complex numbers
a = 2.1+3.14j
l
21
a.rea
l
=
2
.
1
a.Imag = 3.14
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Strings

24
VARIABLES
Strings
 Set of characters between quotation
marks
marks
>>>str1 = 'Hello World!‘
>>>print str1 # Prints complete string
Hello World!
>>>print str1[0] # Prints first character of the string
H
d
th
>>>print str1[2:5] # Prints characters starting from 3
r
d
to 5
th
llo
>>>print str1[2:] # Prints string starting from 3
rd
character
llo World!
>>>print str1*2 # Prints string two times
Hello World! Hello World!
>>> print str1 + "TEST" # Prints concatenated string
Hello World!TEST
eBook for You
Lists
25

VARIABLES
Lists
 Most versatile of Python’s compound data
types
types
 A list contains items separated by
commas and enclosed within square
commas

and

enclosed

within

square

brackets “[ ]”

All the items belonging to a list can be of

All

the

items

belonging

to

a

list

can

be

of

different data type

The values stored in a list can be

The

values

stored

in

a

list

can

be

accessed using the slice operator “[ ]”
with indexes starting at 0 in the beginning
of the list
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