![Python Interpreter
• Interactive interface to Python
% python Python 2.5 (r25:51908, May 25 2007, 16:14:04)
[GCC 4.1.2 20061115 (prerelease) (SUSE Linux)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>>
• Python interpreter evaluates inputs:
>>> 3*(7+2) 27
• Python prompts with ‘>>>’.
• To exit Python: CTRL-D
• Running on UNIX
% python filename.py
• You could make the *.py file executable and add: #!/usr/bin/env python to the
top to make it runnable.](https://image.slidesharecdn.com/pythontechsharing-231015083049-6307c3a5/85/python-pptx-6-320.jpg)
![Loops/Iterations
• sentence = ['Marry','had','a','little','lamb’]
• for word in sentence:
print word, len(word)
• for i in range(10):
print i
for i in xrange(1000): # does not allocate all initially
print i
• while True:
pass
• for i in xrange(10):
if i == 3: continue
if i == 5: break
print i,](https://image.slidesharecdn.com/pythontechsharing-231015083049-6307c3a5/85/python-pptx-10-320.jpg)
![Functions
• def print_hello():# returns nothing
print “hello”
• def has_args(arg1,arg2=['e', 0]):
num = arg1 + 4
mylist = arg2 + ['a',7]
return [num, mylist]
has_args(5.16,[1,'b'])# returns [9.16,[[1, ‘b’],[ ‘a’,7]]
• def duplicate_n_maker(n): #lambda on the fly func.
return lambda arg1:arg1*n
dup3 = duplicate_n_maker(3)
dup_str = dup3('go') # dup_str == 'gogogo'](https://image.slidesharecdn.com/pythontechsharing-231015083049-6307c3a5/85/python-pptx-11-320.jpg)
python.pptx
- 2. Outline • What is Python • History • Python Interpreter • Syntax and Semantics • Control Structures • basic types: numbers, strings • container types: lists, dictionaries, tuples • variables • control structures • functions & procedures • classes & instances • modules & packages • exceptions • files & standard library • Applications
- 3. Python • Simple • Python is a simple and minimalistic language in nature • Reading a good python program should be like reading English • Its Pseudo-code nature allows one to concentrate on the problem rather than the language • Easy to Learn • Free & Open source • Freely distributed and Open source • Maintained by the Python community • High Level Language –memory management • Portable – *runs on anything c code will
- 4. Python • Interpreted • You run the program straight from the source code. • Python program Bytecode a platforms native language • You can just copy over your code to another system and it will auto-magically work! *with python platform • Object-Oriented • Simple and additionally supports procedural programming • Extensible – easily import other code • Embeddable –easily place your code in non-python programs • Extensive libraries • (i.e. reg. expressions, doc generation, CGI, ftp, web browsers, ZIP, WAV, cryptography, etc...) (wxPython, Twisted, Python Imaging library)
- 5. A Bit of History • Python was conceived in the late 1980s. • Guido van Rossum, Benevolent Dictator For Life • Rossum is Dutch, born in Netherlands, Christmas break bored, big fan of Monty python’s Flying Circus • Descendant of ABC programming language, he wrote glob() func in UNIX • Python 0.9.0 (initial version) was published in 1991 • Python 1.0 was released in 1994: included high-order functions (lambda, map, filter, and reduce. • Computer Programming for Everybody (CP4E) initiative • Launched by Rossum to make programming accessible to more people, with basic “literacy” similar to those required for English and math skills for some jobs. • Python 2.2 was released in 2001: Included unification of types and classes into one hierarchy, making pythons object model purely Object-oriented
- 6. Python Interpreter • Interactive interface to Python % python Python 2.5 (r25:51908, May 25 2007, 16:14:04) [GCC 4.1.2 20061115 (prerelease) (SUSE Linux)] on linux2 Type "help", "copyright", "credits" or "license" for more information. >>> • Python interpreter evaluates inputs: >>> 3*(7+2) 27 • Python prompts with ‘>>>’. • To exit Python: CTRL-D • Running on UNIX % python filename.py • You could make the *.py file executable and add: #!/usr/bin/env python to the top to make it runnable.
- 8. Data and Container Types
- 10. Loops/Iterations • sentence = ['Marry','had','a','little','lamb’] • for word in sentence: print word, len(word) • for i in range(10): print i for i in xrange(1000): # does not allocate all initially print i • while True: pass • for i in xrange(10): if i == 3: continue if i == 5: break print i,
- 11. Functions • def print_hello():# returns nothing print “hello” • def has_args(arg1,arg2=['e', 0]): num = arg1 + 4 mylist = arg2 + ['a',7] return [num, mylist] has_args(5.16,[1,'b'])# returns [9.16,[[1, ‘b’],[ ‘a’,7]] • def duplicate_n_maker(n): #lambda on the fly func. return lambda arg1:arg1*n dup3 = duplicate_n_maker(3) dup_str = dup3('go') # dup_str == 'gogogo'