python_skill.txt

1. set
some_list = [1, 2, 3, 4, 5, 2, 5, 1, 4, 8]
even_set = {x for x in some_list if x % 2 == 0}

2. dict
d = {x: x % 2 == 0 for x in range(1, 11)}

3. set string face
my_set = {1, 2, 1, 2, 3, 4}

4. iterator
num = [1, 4, -5, 10, -7, 2, 3, -1]
filtered_squared = [x ** 2 for x in num if x > 0]

5. generator (not need to load all data)
num = [1, 4, -5, 10, -7, 2, 3, -1]
filtered_and_squared = (x ** 2 for x in num if x > 0)
for i in filetered_and_squared:
	print i

6. modify generator
num = [1, 4, -5, 10, -7, 2, 3, -1]
def square_generator(optional_parameter):
	return (x ** 2 for x in num if x > optional_parameter)
print square_generator(0)
for k in square_generator(0);
	print k
g = list(square_generator(0))
print g

7. zip
alist = ['a1', 'a2', 'a3']
blist = ['1', '2', '3']
for a, b in zip(alist, blist):
	print a, b

8. two list
import os
def tree(top):
	for path, names, fnames in os.walk(top):
		for fname in fnames:
			yield os.path.join(path, fname)
 
for name in tree('C:\Users\XXX\Downloads\Test'):
	print name

9. decorators
def hello(fn):
	def wrapper(n):
		while n > 0:
			print "count"
			n -= 1
	return wrapper

@hello
def foo(n):
	pass

foo(10)

@hello
def foo():
foo = hello(foo)

@dec_one
@dec_two
def func()
func = dec_one(dec_two(func))

@dec(arg1, arg2)
def func()
func = dec(arg1, arg2)(func)





u, v, w = w, v, u

d = {'key': 'value'}
print d.get('key', 'not find')

text = string.join([ line for line in open('text.txt')], '')
text = ''.join([ line for line in open('text.txt') ]) 
text = file('text.txt').read()

print (n >= 0) and 'positive' or 'negitive'
print(n >= 0 and ['pos'] or ['neg'])[0]
print ('negitive', 'positive')[n >= 0]

d.setdefault(y, {})[x] = 3
d.setdefault(y, [])[x] = 3

map(lambda x : x + 1, [1, 2, 3])