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
on
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o
P
y
th
on
December 4, 2013Prepared by: Mohamed El Chehaly
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OUTLINE
2
OUTLINE
• Basic Syntax
• Variables

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

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

 Interactive mode programming

Write the following

Write

the

following

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

Basic

Syntax
 Script mode programming

Open new window

Open

new

window



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


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


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

 Statements contained within [ ], { } and ( )
do not need to use the line continuation
ht
c
h
arac
t
er
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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

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

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



List

List

Tuple

Tuple

Dictionary

Dictionary
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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
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Numbers
22


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

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


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