Python Orientation

Python Programming controls The flow of program will be controlled with conditional statements where this flow  if condition if-else condition if-elif condition while loop while - else loop for loop for with if- else loop if condition Here I would like to work on program control statements, wherein relate some operating system functionalities so that, this would give some basic prototype for the sys admin scripts. #!/usr/bin/python # This illustrate if condition # Filename : ifex.py import os d=os.listdir('/home/pavanbsd/pybin') print d f='ifex.py' if f in d: print "File exists" else: print "Not found..." if-elif-else ladder No worries, coming soon... When you need the task that need to be done repeatedly then your choice is using loops. Python provides two simple loop constructs easy to use! More powerful then other scripting compare to, it has 'else' block. while loop Understand the power of while loop,...

Python Sets Python Maps examples A mapping object maps hashable values to arbitrary objects. Mappings are mutable objects. There is currently only one standard mapping type, the dictionary. Dictionaries consist of pairs (called items) of keys and their corresponding values. Dictionaries can be created by placing a comma-separated list of key: value pairs within curly braces Keys are unique within a dictionary while values may not be. The values of a dictionary can be of any type, but the keys must be of an immutable data type such as strings, numbers, or tuples. Python Set Operations and methods Python Set methods continueed >>> SET={'new','old','list','new'} >>> SET set(['new', 'old', 'list']) Lets play with set operations, it is more like school math here... >>> s={1,2,3,4} >>> k={3,4,5,6} >>> len(s) 4 >>> len(k) 4 >>> 1 in s True >>...

The following program will illustrates the method overriding concept onf OOP. Here parent and child classes have defined with the same method name and signature. According to context the method would be executed. The actual meaning of overriding means ignoring the parent method when both have same method signature, and executing the derived class method. ===== METHOD OVERRIDING SAMPLE PROGRAM ===== class FirstClass: #define the super class def setdata(self, value): # define methods self.data = value # ‘self’ refers to an instance def display(self): print self.data class SecondClass(FirstClass): # inherits from FirstClass def display(self): # redefines display print 'Current Data = %s' % self.data x=FirstClass() # instance of FirstClass y=SecondClass() # instance of SecondClass x.setdata('Before Method Overloading') y.setdata('After Method Overloading') x.display() y.display() ===== Static and Class Method Sample Prog...

This session about Python Regular expressions how we can work with patterns and the specific methods available in re module. match() group(), groups() search() compile() sub() Regular expression sample in Python Here is the sample for match function use. #!/usr/bin/python """ This program illustrates the usage of match, group functions in re module This also shows how to use re flags """ import re line = "Python Orientation course helps professionals fish best opportunities" m = re.match( r'(.*) helps (.*?) .*', line, re.I) if m: print "m.group() : ", m.group() print "m.group(1) : ", m.group(1) print "m.group(2) : ", m.group(2) else: print "Don't have match!!" The output >>> execfile('c:/pybin/rematch.py') m.group() : Python Orientation course helps professionals fish best opportunities m.group(1) : Python Orientation course m.group(2) : ...

Heere we have experimenting with functions in Python, Functions can be defined for specific task, functions are prepared to reuse them. modular programming can be defined as breaking the bigger task into chunks of blocks this can be achived with the Python functions. Over all we are going to know in depth knowledge on how Python function is powerful then other structure programs. We have seen some built-in functions which you don't need to import any modules. str(), int(), float(), bool() -- type definitions type(), id(), dir() --  introspecting the functions len(), range() -- sequance collection related functions print(), input(), raw_input() -- input output functions Python Function overview Function definition  Calling Function in assignment Adding DocString to Function  Function Execution – Scope of variables The import and reload Defining inner functions Lambda functions Function definition structure 1. Procedure - which do not ha...

What is Python Module? When a Python shell starts it only has access to a basic python functions (“int”, “dict”, “len”, “sum”, “range”, ...) “Modules” that contain additional functionality more methods, more reusability and more sharability. Use “import” keyword to tell the Python shell to load a module. import os, sys Namespaces are one honking great idea -- let's do more of those! (Zen of Python) import this Why importing modules in Python? The major advantage comes when you split your program into several files for easier maintenance. How to import modules in Python A module can be imported by another program to make use of its functionality. This is how we can use the Python standard library as well You can import multiple modules. import module1[, module2[,... moduleN] Normally after module import we can use its containing functions by calling them with refering with the module name followed by period or dot(.) and the function/procedure name. import...

How to make this FILE process in Python?  The Standard Input, Standard Output are the two fileobjects genrally accessible from the operating system provided interfaces which allows us to change files. How to redirect this output... normally output is coming from print command in the Python. Can you send the data/text to a file? Yes we can using file object. File IO Process in Python The file open modes Python file open modes are same as C language by default it will be open in read mode. The open() method returns a file object or file pointing reference.  Syntax:  fileobject = open(file_name [, access_mode][, buffering])  where basic file operational mode can be 'r' (read), 'w'(write) or 'a'(append).  The default mode is 'r' that is read mode and the file can be ANSI Text file or binary file (b). They can be opened in combined mode ‘rb+’  That every file that you opened in the code must be closed. The close() method closes an ope...