poros

'lmnop' in 'abcdefghijklmnopqrstuvwxyz'


index = 'python'.find('on')  # 4 

poros

try:
    f = open(filename, 'r')
except IOError as e:
    print 'cannot open ', filename
    print "I/O error({0}): {1}".format(e.errno, e.strerror)
except:
    log.exception("Unexpected error")
    # print "Unexpected error:", sys.exc_info()[0]
    raise
else:

poros

[x**2 for x in (2,4,6)]

{x: x**2 for x in (2, 4, 6)}

{x for x in 'abracadabra' if x not in 'abc'}

poros

matrix = [[1,2,3]] * 4
[[1, 2, 3], [1, 2, 3], [1, 2, 3], [1, 2, 3]]

# FLATTEN THE MATRIX
flatten = []
for row in matrix:
    for i in range(3):
        flatten.append(row[i])

[row[i] for row in matrix for i in range(3)]

poros

for i in range(len(colors)):
    print i, colors[i]
  
  
for i, colors in enumerate(colors):
    print i, colors
# retuns enumerate object, not a list

poros

n = min(len(names), len(colors))
for i in range(n):
    print names[i], colors[i]
    

for names, color in zip(names, colors):
    print name, color

#collections.izip is the iterator version

poros

d = {}
for name in names:
    key = len(name)
    if key not in d:
        d[key] = []
    d[key].append(name)


# slightly better
d = {}

poros

colors = ['green', 'blue', 'green', 'red', 'blue', 'green']

d = {}
for color in colors:
    if color not in d:
        d[color] = 0
    d[color] += 1


# slighlty better

poros

d = defaults.copy()
d.update(os.environ)
d.update(command_line_arguments)

# PYTHON3 ONLY!!!
from collections import ChainMap
d = ChainMap(command_line_arguments, os.environ, defaults)

# it's view, not a real dictionary. if you want something equivalent to a new one
d = ChainMap({}, command_line_arguments, os.environ, defaults)

poros

def fibonacci(n):
    x = 0
    y = 1
    for i in range(n):
        print x
        tmp = y
        y = x + y
        x = tmp