The Power and Simplicity of Python Programming
Python
Ko-Lung Yuan
Why Python?
•
Simple and elegant
•
Good readability
•
Object-oriented / dynamic(script) language
•
High productivity
•
Abundant resources(libraries…)
•
Active community
•
Wide range of uses
•
Embeddable and Extendibility
•
Interactive Learning / well document
Python’s history
•
http://zh.wikipedia.org/wiki/Python
Guido van Rossum
Zen of Python
•
Beautiful is better than ugly.
•
Explicit is better than implicit.
•
Simple is better than complex.
•
Complex is better than complicated.
•
Flat is better than nested.
•
Sparse is better than dense.
•
Readability counts.
•
Special cases aren't special enough to break the rules.
•
Although practicality beats purity.
•
Errors should never pass silently.
•
Unless explicitly silenced.
•
In the face of ambiguity, refuse the temptation to guess.
•
There should be one-- and preferably only one --obvious way to do it.
•
Although that way may not be obvious at first unless you're Dutch.
•
Now is better than never.
•
Although never is often better than *right* now.
•
If the implementation is hard to explain, it's a bad idea.
•
If the implementation is easy to explain, it may be a good idea.
•
Namespaces are one honking great idea -- let's do more of those!
Python
之禪
•
美麗優於醜陋，明講好過暗諭。
•
簡潔者為上，複雜者次之，繁澀者為下。
•
平舖善於層疊，勻散勝過稠密；以致輕鬆易讀。
•
特例難免但不可打破原則，務求純淨卻不可不切實際。
•
斷勿使錯誤靜靜流逝，除非有意如此。
•
在模擬兩可之間，拒絕猜測的誘惑。
•
總會有一種明確的寫法，最好也只有一種，
•
但或須細想方可得。
•
凡事雖應三思後行，但坐而言不如起而行。
•
難以解釋的實作方式，必定是壞方法。
•
容易解釋的實作方式，可能是好主意。
•
命名空間讚，吾人多實用。
蟒之道
•
妍優於寢 喻莫如敘 是故簡勝繁 繁勝亂
•
平舖勝汲營 綿密不如疏俊 唯平易而已
•
無例外於其例 不獨清於實際
•
毋默於誤 其惡非務
•
寧戚戚於尋徑 勿揣揣於模稜
•
道謀於一 可以得矣
•
力行者宜立行於當下 利行者長三思而後行
•
不可說之說不可說 可以道之道可以道
•
名域鳴於域 可取
How to Get Python
•
Official website:
http://www.python.org/
Install Python
•
Python Interpreter and Libraries
•
Linux
: sudo apt-get install python3.1-dev
IDLE
•
A basic but useful editor for Python
•
Text-Indent
•
Keyword-Highlight
•
Interactive interface
•
Easy to test code
First, We should know…
•
No semicolon (
;
)
•
No brace (
{ })
•
Using colon (
:
)
•
Using text-Indent
X
X
O
O
Comment
•
Single-line comment (
#
)
# This is an example of single-line comment
•
Multi-line comment (
“”” “””
)
“””This is an example of multi-line comment
You can write the comment in several lines”””
Variable
•
Build variable (
Var = …
)
Var = 70
Var = 6.78
Var = “alcom lab”
•
No declaration
but
definition
and
type
•
Naming Rule
•
No need to worry about where the variables and
their sizes,
all of the details are hided
!
Input and Output
•
Output (
print()
)
print(100)
print(“a=”,a)
•
Input (
raw_input(
[hint]
)
)
raw_input(“name:”)
String
•
Using quote (
‘ ’
,
“ ”
,
“”” ”””
)
s1=‘apple’
s2=“banana”
s3=“””I love you”””
print(s1,s2,s3)
•
Strings are unchanged object
•
Using
escape characters(e.g. /n)
String Operation
•
Concatenate(
+
)
“alcom”+”lab”
•
Repeat(
*n
)
“go”*3
•
Length(
len()
)
len(“three”)
•
Exist(
in
)
‘a’ in ‘apple’
•
Split(
.split(“string”)
)
“abc cde”.split(“ ”)
Mathematic Type
•
Integer
- no limit
123123123112432532643877698709760909
•
Float
– Not exact, support science notation
123.456
1.2e-3
•
Complex number
1+2j
1.23+34.7+5j
Mathematic Operation
•
Basic operation
+ - * / %
•
Floating Point –
base on simple one
10/3
50*0.5
10+3j-3j
•
Special operation
** //
16**0.5
10.0//3.0
All things in python are objects!
List
•
An ordered data structure (Like array)
•
Mutable Sequence
•
[object 1, object 2, …]
listex = [1, 2.34, ”alcom”, 7+8j]
•
Support Nested List
nestlist = [ [1,2,3] , [4.2, “john”], Var]
•
Access method
listex[-1]
nestlist[0][2]
List Operation
•
Length
len(nestlist)
•
Append
listex.append(20)
•
Extend
listex.extend([2,3,4])
•
Count
[1,1,2,3].count(1)
•
Index
[1,1,2,3].index(1)
•
Insert
[1,1,2,3].insert(1,1)
•
Pop
[1,1,2,3].pop()
•
Remove
[1,1,2,3].remove()
•
Reverse
[1,2,3,4].reverse()
•
Sort
[1,2,3,4].sort()
Dictionary
•
Dictionary is a mapping object
Key
value
D = { key1:value1, key2:value2, …}D[key] = value
D[key]
•
Dictionary is unordered
•
Set
is another unordered data structure
Slice
•
S[ i ]
•
S[ i : j ]
•
S[ i : j : k ]
•
Some examples
If else
if condition:
…
elif condition:
…
else:
…
PS : Text-Indent!!
Logical Operation
•
==
•
!=
•
< > <= >=
•
Or
•
And
•
Not
•
Boolean value:
True False
For Loop
For
Var
in
container
:
…code…
…code…
For
Var
in
range(x)
:
…code…
…code…
Container
•
Container are the iterative objects
•
List
: elements of list
•
Dictionary
: keys of dictionary
•
Tuple
: elements of tuple
•
File
: lines of file
•
range(x)
: build a list
[0, 1, 2, … ,x-1]
In and List Comprehension
•
In
is an useful keyword
1.
in relation
if a
in
“abc”
2.
for iteration
for a
in
list:
•
List Comprehension
List = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
List2 = [item*10
for
item
in
List]
While Loop
While
condition:
…code…
While
True
:
…code…
Nested Structure
•
We can use nested structure in python
•
For loop
•
While loop
•
If elif else
Build-in Function
•
Length:
len()
•
Sort:
sorted()
V.s.
object.sort()
Function Factory
•
Change object type!
•
int( )
•
str( )
•
float( )
Module / Import / Namespace
•
A .py file is a
module
whose name is same as
the file name
•
Use module by
import
import
sys
•
Every module has a
namespace
of its own
–
Original-> (main)
–
Import one-> It’s name
User Function
•
def
funciton_name(parameters[=default value]):
…function description…
•
Call function
namespace.function_name(parameters)
namespace.function_name(parameters,
appointed parameter1=value,
appointed parameter2=value, …)
Other important issues
•
User Object
•
File IO (simple demo)
•
Exception Handling
•
Pypi
•
pickle
Strong Python
•
APPs
•
Website(server program)
•
Linux Shell Script / Linux Managing
•
Latex
•
Combine with C/C++
Python with Linux (1/2)
•
#!/usr/bin/python
•
# -*- coding: UTF-8 -*-
•
Import os
and
shutil
•
os.unlink('data.new.txt')•
os.rename('data.txt', 'data.alter.txt')•
shutil.copy('data.txt', 'data.new.txt')•
shutil.move('data.alter.txt', 'data.txt')•
chmod a+x python-script-file
Python with Linux (2/2)
•
Run outer program
os.system(“program”)
•
Pipeline and get the return value
import popen2
stdout, stdin = popen2.popen2(“ls”)
ostr = stdout.read()
print(ostr)
Python with C/C++
•
http://docs.python.org/extending/extending.
html
Python with Latex
•
http://www.texample.net/weblog/2008/oct/2
4/embedding-python-latex/
Useful Books
•
Head First Python
•
Dive into Python
•
Programming in Python3
•
Python Essential Reference
•
Learning Python
Useful Websites
•
http://ez2learn.com/index.php/python-
tutorials
•
http://wiki.python.org.tw/
•
http://caterpillar.onlyfun.net/Gossip/Python/i
ndex.html
•
http://pypi.python.org/pypi
Python is praised for its simplicity, elegance, and readability, making it an ideal choice for beginners and experts alike. This versatile language is object-oriented, dynamic, and highly productive with a vast array of libraries and an active community. Python's history, Zen philosophy, and practical usage make it a top choice for various applications. From installation to basic syntax, this guide provides an overview of Python's key features and benefits.
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Presentation Transcript
Python Ko-Lung Yuan
Why Python? Simple and elegant Good readability Object-oriented / dynamic(script) language High productivity Abundant resources(libraries ) Active community Wide range of uses Embeddable and Extendibility Interactive Learning / well document
Pythons history http://zh.wikipedia.org/wiki/Python Guido van Rossum
Zen of Python Beautiful is better than ugly. Explicit is better than implicit. Simple is better than complex. Complex is better than complicated. Flat is better than nested. Sparse is better than dense. Readability counts. Special cases aren't special enough to break the rules. Although practicality beats purity. Errors should never pass silently. Unless explicitly silenced. In the face of ambiguity, refuse the temptation to guess. There should be one-- and preferably only one --obvious way to do it. Although that way may not be obvious at first unless you're Dutch. Now is better than never. Although never is often better than *right* now. If the implementation is hard to explain, it's a bad idea. If the implementation is easy to explain, it may be a good idea. Namespaces are one honking great idea -- let's do more of those!
How to Get Python Official website: http://www.python.org/
Install Python Python Interpreter and Libraries Linux: sudo apt-get install python3.1-dev
IDLE A basic but useful editor for Python Text-Indent Keyword-Highlight Interactive interface Easy to test code
First, We should know X X O O No semicolon ( ; ) No brace ( { } ) Using colon ( : ) Using text-Indent
Comment Single-line comment ( # ) # This is an example of single-line comment Multi-line comment ( ) This is an example of multi-line comment You can write the comment in several lines
Variable Build variable ( Var = ) Var = 70 Var = 6.78 Var = alcom lab No declaration but definition and type Naming Rule No need to worry about where the variables and their sizes, all of the details are hided!
Input and Output Output ( print() ) print(100) print( a= ,a) Input ( raw_input( [hint]) ) raw_input( name: )
String Using quote ( , , ) s1= apple s2= banana s3= I love you print(s1,s2,s3) Strings are unchanged object Using escape characters(e.g. /n)
String Operation Concatenate( + ) alcom + lab Repeat( *n ) go *3 Length( len() ) len( three ) Exist( in ) a in apple Split( .split( string ) ) abc cde .split( )
Mathematic Type Integer - no limit 123123123112432532643877698709760909 Float Not exact, support science notation 123.456 1.2e-3 Complex number 1+2j 1.23+34.7+5j
Mathematic Operation Basic operation + - * / % Floating Point base on simple one 10/3 50*0.5 10+3j-3j Special operation ** // 16**0.5 10.0//3.0
List An ordered data structure (Like array) Mutable Sequence [object 1, object 2, ] listex = [1, 2.34, alcom , 7+8j] Support Nested List nestlist = [ [1,2,3] , [4.2, john ], Var] Access method listex[-1] nestlist[0][2]
List Operation Length Append Extend Count Index Insert Pop Remove Reverse Sort len(nestlist) listex.append(20) listex.extend([2,3,4]) [1,1,2,3].count(1) [1,1,2,3].index(1) [1,1,2,3].insert(1,1) [1,1,2,3].pop() [1,1,2,3].remove() [1,2,3,4].reverse() [1,2,3,4].sort()
Dictionary Dictionary is a mapping object Key value D = { key1:value1, key2:value2, } D[key] = value D[key] Dictionary is unordered Set is another unordered data structure
Slice S[ i ] S[ i : j ] S[ i : j : k ] Some examples
If else if condition: elif condition: else: PS : Text-Indent!!
Logical Operation == != < > <= >= Or And Not Boolean value: True False
For Loop For Var in container: code code For Var in range(x): code code
Container Container are the iterative objects List: elements of list Dictionary: keys of dictionary Tuple: elements of tuple File: lines of file range(x): build a list [0, 1, 2, ,x-1]
In and List Comprehension In is an useful keyword 1. in relation 2. for iteration if a in abc for a in list: List Comprehension List = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10] List2 = [item*10 for item in List]
While Loop While condition: code While True: code
Nested Structure We can use nested structure in python For loop While loop If elif else
Build-in Function Length: len() Sort: sorted() V.s. object.sort()
Function Factory Change object type! int( ) str( ) float( )
Module / Import / Namespace A .py file is a module whose name is same as the file name Use module by import import sys Every module has a namespace of its own Original-> (main) Import one-> It s name
User Function def funciton_name(parameters[=default value]): function description Call function namespace.function_name(parameters) namespace.function_name(parameters, appointed parameter1=value, appointed parameter2=value, )
Other important issues User Object File IO (simple demo) Exception Handling Pypi pickle
Strong Python APPs Website(server program) Linux Shell Script / Linux Managing Latex Combine with C/C++
Python with Linux (1/2) #!/usr/bin/python # -*- coding: UTF-8 -*- Import os and shutil os.unlink('data.new.txt') os.rename('data.txt', 'data.alter.txt') shutil.copy('data.txt', 'data.new.txt') shutil.move('data.alter.txt', 'data.txt') chmod a+x python-script-file
Python with Linux (2/2) Run outer program os.system( program ) Pipeline and get the return value import popen2 stdout, stdin = popen2.popen2( ls ) ostr = stdout.read() print(ostr)
Python with C/C++ http://docs.python.org/extending/extending. html
Python with Latex http://www.texample.net/weblog/2008/oct/2 4/embedding-python-latex/
Useful Books Head First Python Dive into Python Programming in Python3 Python Essential Reference Learning Python
Useful Websites http://ez2learn.com/index.php/python- tutorials http://wiki.python.org.tw/ http://caterpillar.onlyfun.net/Gossip/Python/i ndex.html http://pypi.python.org/pypi
