Overall

Indendation matters!

Python is case sensitive

Comments: # , or """multiline comment """

a=b=c=1 defines a, b, and c to be 1

a,b,c = 1, 1.0, "Hello Glorious World"

Logical

==, !=, <, >, <=, >-
and, or, not
in, not in
is, is not (x is y, here is results in 1 if id(x) equals id(y).)
In general, 0 is FALSE, and all other numbers are TRUE
- x or y
- x and y
- not x

Arithmatic

+, -, *, /
% (remainder), ** (exponent), // (floor division)

Assignment Operators

= Simple assignment
c += a is equivalent to c = c + a
c -= a is equivalent to c = c - a
c *= a is equivalent to c = c * a
c /= a is equivalent to c = c / a
c %= a is equivalent to c = c % a
c **= a is equivalent to c = c ** a
c //= a is equivalent to c = c // a

Conditional Assignment

x = 3 if (y == 1) else 2
x = 3 if (y == 1) else 2 if (y == -1) else 1
# also valid: x = (class1 if y == 1 else class2)(arg1, arg2)

Functions

def FUN(parameters):
    """ docstring """
    # do stuff
    return ...

Data Types

Numbers:

int(), long(), float(), and complex()
Numbers allow the use of math.floor(), math.ceil(), math.round(x[, n])

Strings: If lala="omg so cool", then
lala[0:4] is "omg".
lala[0:4]*2 is "omgomg".
lala + " PUMPKIN!" is "omg so cool PUMPKIN!"
%
>>> print '%(lang)s has %(n)03d quote types.' % \
... {"lang": "Python", "n": 2}
Python has 002 quote types.

Lists[ ]: Very versatile! Unfrozen Tuples.
IF li = [1, 12.02, "Cheese"]
li[0:] is [1, 12.02, "Cheese"]
li[0:2] is [1, 12.02]
li[1] is 12.02
li[-1] is "Cheese"
li.append("b") is [1, 12.03, "Cheese", "b"]
li.insert(2, "1") is [1, 12.013, "1", "Cheese"]
li.extend(["1","2"]) is [1, 12.03, "Cheese", "1", "2"]
[0,9]*2 returns [0,9,0,9]

Tuples( ): In short, frozen lists. No .append, .extend, .insert.

Dictionaries{ }: UNORDERED
d={'one':1, 'two':2} #or
d={}
d['one'] = 1 ; d['two'] = 2
THEN
    d['one'] is 1
    d.keys() is ['one', 'two']
    d.values() is [1, 2]

Truth Value Testing

Any object can be tested for truth value. Basically any empty object, None, or False is considered False:
- None
- False
- 0, 0.00, etc.
- "", [], or ()
- {}
- an object with length 0

Flow Control

If (else) statements

if a>b:
    print b
else:
    print a

Loops
for, while
Control Statements:
    break (terminates the loop)
    continue (skip the remainder and continue to the next iteration)
    pass (used when a statement is required syntactically but you do not want any command or code to execute.)

Nested List comprehensions

[(i,j) for i in range(3) for j in range(i) ]
((i,j) for i in range(4) for j in range(i) )

Exception else clause

try:
    put_4000000000_volts_through_it(parrot)
except Voom:
    print "'E's pining!"
else:
    print "This parrot is no more!"
finally:
    end_sketch()

Argument Unpacking

def some_function(x, y):
# do some magic

tuple_foo = (3, 4)
dict_bar = {'y': 3, 'x': 2}

some_function(*tuple_foo)
some_function(**dict_bar)

Slice Operators

a = [1,2,3,4,5]
# iterate over the whole list in 2-increments
>>> a[::2]
[1,3,5]

# reverse a list:
>>> a[::-1]
[5,4,3,2,1]

Chaining Comparison Operators

>>> x = 5
>>> 1 < x < 10
True
>>> 10 < x < 20
False
>>> x < 10 < x*10 < 100
True
>>> 5 == x > 4
True

Readable, multi-line regular expressions

>>> pattern = """
... ^ # beginning of string
... M{0,4} # thousands - 0 to 4 M's
... (CM|CD|D?C{0,3}) # hundreds - 900 (CM), 400 (CD), 0-300 (0 to 3 C's),
... # or 500-800 (D, followed by 0 to 3 C's)
... $ # end of string
... """
>>> re.search(pattern, 'M', re.VERBOSE)