Python Recipes

It has been months since i wrote something here.During the intervening time i happened to see ‘Python Cookbook’ and i am publishing my notes and examples here,hoping that someone like me will find them useful.

Swapping Values Without Using a Temporary Variable

In python we don’t have to use temporary variables to swap variable values.Python’s automatic tuple packing and unpacking make this a snap:

a, b, c = b, c, a

Constructing a Dictionary Without Excessive Quoting

When the keys are identifiers, a cleaner way is

Getting a Value from a Dictionary

We need to obtain a value from a dictionary, without having to handle an exception if the key you
seek is not in the dictionary.We usually use like

let d = {‘a’:1, ‘b’:2 ,’c’:3} is the dictionary then

if d.has_key('a'):
    print d['a']
else:
    print 'not found'

However, there is a much simpler syntax:

print d.get('a', 'not found')

Example: