Here are some of Pythonic experts signatures,..

As a junior programmer when I started out, I did find very difficult to understand or use some of these but as I have started learning I find these simple tips are help me to code faster. If you are a fresher, I would suggest learn these 5 - any, all, lambda, filter, lists

# As a jr. this is how I wrote code earlier
int i,j;
j = 10;
while i < j:
   print i
   i = i + 1;

# Today, I am search better one for below
for i in range(10):
  print i

Tip: 21

def map_example(my_iterable):
 return list(map(lambda x: x + 1, my_iterable))

my_list = [1,2,3,4,5]
print(map_example(my_list))

def filter_example(my_iterable):
 return list(filter(lambda x: x > 3, my_iterable))

my_list = [1,2,3,4,5,6]
print(filter_example(my_list))

Tip: 21

filtered = [x for x in range(1,10) if x % 2==0 ]
mapped = [f(x) for x in range(1,10) ]

filtered = filter(lambda x: x%2==0, range(1,10))
mapped = map(f,range(1,10))

Tip: 21

map(str, collection)

[str(elem) for elem in collection]

Tip: 21

import operator as op

op_map = {
 '$lt': op.lt,
 '$lte': op.le,
 '$gt': op.gt,
 '$gte': op.ge,
 '$ne': op.ne,
 '$eq': op.eq}

if cond_test in ['$eq', '$ne', '$gt', '$gte', '$lt', '$lte']:
 return op_map[cond_test](elem1, elem2):
return False

Tip: 21

def test_vaarg(**kwargs):
 for key in kwargs:
 print kwargs[key]

Tip: 21

 Chaining comparison

>>> x = 5
>>> 1 < x < 10
True
>>> 10 < x < 20 
False
>>> x < 10 < x*10 < 100
True

Tip: 21

 enumerate

>>> a = ['a', 'b', 'c', 'd', 'e']
>>> for index, item in enumerate(a): print index, item
...
0 a
1 b
2 c
3 d
4 e

Tip: 21

>>> n = ((a,b) for a in range(0,2) for b in range(4,6))
>>> n
<generator object <genexpr> at 0x02086418>
>>> list(n)
[(0, 4), (0, 5), (1, 4), (1, 5)]

Tip: 21

 Decorators 
>>> def print_args(function):
>>> def wrapper(*args, **kwargs):
>>> print 'Arguments:', args, kwargs
>>> return function(*args, **kwargs)
>>> return wrapper

>>> @print_args
>>> def write(text):
>>> print text

>>> write('foo')
Arguments: ('foo',) {}
foo

Tip: 21

Conditional Assignment

x = 3 if (y == 1) else 2

>>> print("The {foo} is {bar}".format(foo='answer', bar=42))

Tip: 21

Nested list comprehensions and generator expressions:

[(i,j) for i in range(3) for j in range(i) ]

Tip: 21

You can easily transpose an array with zip.

a = [(1,2), (3,4), (5,6)]
zip(*a)

Tip: 21

hello = "Greaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa Hello " \
 "Word"
or

hello = ("Greaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa Hello " 
 "Word")

Tip: 21

import unittest, textwrap

class XMLTests(unittest.TestCase):
 def test_returned_xml_value(self):
 returned_xml = call_to_function_that_returns_xml()
 expected_value = textwrap.dedent("""\
 
 
 my_content
 
 """)

 self.assertEqual(expected_value, returned_xml)

Tip: 21

if isinstance (number, float) or isinstance (number, int): 
 print "yaay"

Tip: 21

> int('10', 0)
10
>>> int('0x10', 0)
16
>>> int('010', 0) # does not work on Python 3.x
8
>>> int('0o10', 0) # Python >=2.6 and Python 3.x
8
>>> int('0b10', 0) # Python >=2.6 and Python 3.x
2

Source of Information:

  • http://www.reddit.com/r/dailyprogrammer/comments/2d957i/weekly_6_python_tips_and_tricks/

  • http://stackoverflow.com/questions/101268/hidden-features-of-python

  • http://www.secnetix.de/olli/Python/lambda_functions.hawk