Python profiling

Profiling in python is very handy. It will help you to monitor your code performance and find the hot spot of your code.
Here I am using cProfile for profiling. It is built in with python.

Download sample code , unzip the file and cd to the folder.
No run this command python -m cProfile a.py
Output will be

Visualization of cProfile data:

I used RunSnakeRun for visualization.
Now run this following two command (make sure you installed RunSnakeRun)
python -m cProfile -o file.prof a.py
runsnake file.prof
Output will be

Check it out.

Min, max value and index from list

See also enumerate and operator.itemgetter

import operator
a = [2, 5, 1, 4, 8, 71, 4, 1, 21]
min_i, min_v = min(enumerate(a), key = operator.itemgetter(1))
max_i, max_v = max(enumerate(a), key = operator.itemgetter(1))

print "[Min] index:",min_i,"value:",min_v
print "[Max] index:",max_i,"value:",max_v

Output:

[Min] index: 2 value: 1
[Max] index: 5 value: 71

Python: Absolute difference between successive elements in list

See also abs, zip and islice

from itertools import islice

a = [1, 4 , 2 , 6 , 7, 3]
result = [abs(p-q) for p, q in zip(a, islice(a, 1, None))]

print result

Output:

[3, 2, 4, 1, 4]

Python multi threading vs multi processing

A very good article on python multi threading vs multi processing

Python Requests: HTTP for Humans

Python requests module provides very interactive way to access web content via proper HTTP protocol.

Installation:
Here is the installation manual. You can also install using pip :
pip install requests

import requests

r = requests.get('https://api.github.com/user', auth=('user', 'pass'))
print r.status_code
print r.headers['content-type']
print r.encoding
print r.text
print r.json()

Output:

200
'application/json; charset=utf8'
'utf-8'
u'{"type":"User"...'
{u'private_gists': 419, u'total_private_repos': 77, ...}

Python webbrowser

Python webrowser provides high-level interface to displaying Web-based documents.

import webbrowser

url ='https://docs.python.org'
webbrowser.open(url, new=0, autoraise=True)

Output:

This code will open url to existing web browser and raised the window.

Python unittest examle

All source code available on github

Python unittest example. Here I am testing my insertion sort code.

import random
import unittest


def insert(A,i):
    value = A[i]
    j = i
    while j != 0 and A[j-1]>value:
        A[j] = A[j-1]
        j = j - 1
    A[j] = value


def insertion_sort(A):
     for i in range(len(A)):
         insert(A, i)

class TestInsertionSort(unittest.TestCase):

    def setUp(self):
        print "Setup ..."

    def testSortRange(self):
        print "TestSortRange .... \n"
        n = 10
        a = range(n)
        random.shuffle(a)
        insertion_sort(a)
        self.assertEqual(a, range(n))

        n = 1
        a = range(n)
        random.shuffle(a)
        insertion_sort(a)
        self.assertEqual(a, range(n))

        n = 77
        a = range(n)
        random.shuffle(a)
        insertion_sort(a)
        self.assertEqual(a, range(n))

    def testSortData(self):
        print "TestSortData .... \n"
        a = []
        r = []
        insertion_sort(a)
        self.assertEqual(a, r)

        a = [3, 1, 2]
        r = [1, 2, 3]
        insertion_sort(a)
        self.assertEqual(a, r)


if __name__=="__main__":
    suite = unittest.TestLoader().loadTestsFromTestCase(TestInsertionSort)
    unittest.TextTestRunner(verbosity=2).run(suite)

Output:

testSortData (__main__.TestInsertionSortSetup ..) ... ok
.
TestSortData .... 

Setup ...
TestSortRange .... 

testSortRange (__main__.TestInsertionSort) ... ok

----------------------------------------------------------------------
Ran 2 tests in 0.000s

OK
[Finished in 0.1s]