Pythonic syntax

Pythonic syntax is a syntax that uses the most efficient idioms for the small code patterns

There is always a better way to program while using python.I have been using python for some time now.The big mistake people do while starting with python is that thinking it a s a java alternative.As predominantly introduced to java or C++ earlier in life people use the same paradigm of programming while coding in python.This makes python code look ugly , run slower unthinkably large and very very slow.

List Comprehensions
List comprehensions are compact way to build a list in python.consider a program to generate all even numbers within say 10.The usual way of doin things is:
>>>while i>>evens
But this style of coding in python does not harness the immense power the language offers.Consider how to do this with List comprehension:
>>>evens=[i for i in range(10) if i%2==0]

Iterators and Generators:
All looping in python is in turn implemented using the iterator protocol in python.An iterator class contains two methods namely:

next():The next method returns the next value in the class and on reaching the last value raises StopIteration Exception.

__iter__():This method just returns the iterator itself.

They are created with iter builtin function by the following way.

Python generators:
To say simply a generator is method that has a yield statement.Rather than returning a single value(say the lines of a file )we generate a series of values using yield statement.

def countdown(n):
while n > 0:
yield n
n -= 1
>>> for i in countdown(5):
… print i,

5 4 3 2 1

So creating an instance of countdown(remember functions are first class objects) will only create a generator object not execute the method.

Counting down from n 10
Generators in real time can be constructed fairly simply by the following way:
>>>capital=(n.capitalize() for n in name)

This can be used to read very large files or fetch database records with fairly simpler and more beautifull syntax and is less memory intensive.


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