Python Mini Tutorial

Description

THE US NATIONAL VIRTUAL OBSERVATORY
P ython Mini T utorial
Shui H ung Kwok
W. M. Keck O bservatory
September 7, 20 0 6
09/07/06N VO SS 2006 1What is P ython?
• P rogramming language
– Created by G uido van Rossum
• Interprets compiled byte code
• D ynamically typed
– T ype goes with values instead of containers
• First released in 1991
– Smalltalk:71, P erl:1987, T cl:1988, Java:1990 , P H P :1994
• Current version: 2.4.3 (March 2006)
09/07/06N VO SS 2006 2D ownload and Installation
• http:/ /www.python.org/download
• See G ettingP ythonSO AP .html
– fpconst and SO AP P y
– MySQ LD B
– P ython Imaging Library
• Start python
$ python
09/07/06N VO SS 2006 3H ello World!
P ython 2.4.3 (#2, Jun 17 2006, 22:02:40)
[G CC 4.0.1 (Apple Computer, Inc. build 53 41)] on darwin
T ype "help", "copyright", "credits" or "license" for more information.
>>>
>>> print “H ello World!”
H ello World!
>>> print 2+3
5
>>> Crtl-D to quit
09/07/06N VO SS 2006 4H ello World!
print “H ello World!”
• Save in file ex1.py
• $ python ex1.py
• H ello World!
09/07/06N VO SS 2006 5Interesting D ata T ypes
• Sequences mutable
– Lists
• a = [1,2,3 ]
– T uples
• b = (1,2,3 ) inmutable
• s = “T his is a string”
• D ictionaries
– ie {'key': 'value', 'a' : 'b'}, d['k'] = 'v‘
• Sets
09/07/06N VO SS 2006 6Statements
• Assigments
a = 1–
a,b,c = 99, 41, 5–
a,b,c = s–
• Special statements
– pass
– global
– print
– del, raise, assert, exec
09/07/06N VO SS 2006 7Control Flow Statements
• If ... [elif ... ...

Sujets

• DeFRaG
• Orbite cristallographique
• Courvite de Coromandel
• 1 rue Sésame
• Web Services Description Language
• N-uplet

Informations

• Publié par: Vewyer
• Nombre de lectures: 76
• Langue: English

Extrait

>> >>> print “H ello World!”H ello World!>>> print 2+35>>> Crtl-D to quit09/07/06N VO SS 2006 4H ello World!print “H ello World!”• Save in file ex1.py• $ python ex1.py• H ello World!09/07/06N VO SS 2006 5Interesting D ata T ypes• Sequences mutable– Lists• a = [1,2,3 ]– T uples• b = (1,2,3 ) inmutable• s = “T his is a string”• D ictionaries– ie {'key': 'value', 'a' : 'b'}, d['k'] = 'v‘• Sets09/07/06N VO SS 2006 6Statements• Assigmentsa = 1–a,b,c = 99, 41, 5–a,b,c = s–• Special statements– pass– global– print– del, raise, assert, exec09/07/06N VO SS 2006 7Control Flow Statements• If ... [elif ... ..." />

T HE US N ATIONAL V IRTUAL O BSERVATORY

Python Mini Tutorial

Shui Hung Kwok W. M. Keck Observatory September 7, 2006

NVOSS 2006

09/07/06

1

What is Python?

• • • • •

Programming language – Created by Guido van Rossum Interprets compiled byte code Dynamically typed – Type goes with values instead of containers First released in 1991 – Smalltalk:71, Perl:1987, Tcl:1988, Java:1990, PHP:1994 Current version: 2.4.3 (March 2006)

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Download and Installation

•

•

•

http:/ /www.python.org/download

See GettingPythonSOAP.html – fpconst and SOAPPy – MySQLDB – Python Imaging Library

Start python $ python

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3

Hello World!

Python 2.4.3 (#2, Jun 17 2006, 22:02:40)

[GCC 4.0.1 (Apple Computer, Inc. build 5341)] on darwin

Type "help", "copyright", "credits" or "license" for more information. >>>   >>> print “Hello World!” Hello World!   print 2+3 >>> 5 >>> Crtl-D to quit

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Hello World!

•

• •

print “Hello World!”

Save in file ex1.py

$ python ex1.py Hello World!

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5

Interesting Data Types

•

• •

Sequences – Lists • a = [1,2,3] – Tuples • b = (1,2,3) • s “This is a string” = Dictionaries – ie {'key': 'value', 'a' : 'b'}, d['k'] = 'v‘    Sets

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mutable

inmutable

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6

Statements

•

•

Assigments – a = 1 – a,b,c = 99, 41, 5 – a,b,c = s

Special statements

– pass

– global

– print

– del, r

del, raise, assert, exec

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Control Flow Statements

•

•

If ... [elif ... else] if a == c: print “a equals c”   else: print “a and c are different”

While ... [else] while a == b: work () else: finalize ()

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For Loops

•

For loop for item in sequence: Statements else: statements

–

Example: for item in (1,3,5,7,9,15,2003): print item for item in xrange (1, 50): sum += item

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Exceptions

• • • •

assert expr, [ message] try ... except ... else try ... finally raise ...

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Functions/Methods

• •

•

def functionName  (params…): Parameters def func1 (a,b,c): def func2 (a,b,*t): # t is a tuple def func3(u,*v,**w): # v is a tuple, w is a dictionary Invocation func1 (1,2,3) func1 (c=5, b=2, a=2) func2 (1, 2, 99, 98, 95) # t=(99,98,95) func3 (1, 2, 99, h=9, k=8) # t=(99), w = {‘h’:9,’k’:8}

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