• Negative indexing starts with -1
• filter(function, sequence) returns a sequence consisting of those items from the sequence for which function(item) is true

  >>>def f(x): return x % 3 == 0 or x % 5 == 0
  >>> filter(f, range(2, 25))
  [3, 5, 6, 9, 10, 12, 15, 18, 20, 21, 24]
  

• map(function, sequence) calls function(item) for each of the sequence’s items and returns a list of the return values

  >>> seq = range(8)
  >>> def add(x, y): return x+y
  ...
  >>> map(add, seq, seq)
  [0, 2, 4, 6, 8, 10, 12, 14]
  

• reduce(function, sequence) returns a single value constructed by calling the binary function function on the first two items of the sequence

  >>> def add(x,y): return x+y
  ...
  >>> reduce(add, range(1, 11))
  55
  

• When looping through a sequence, the position index and corresponding value can be retrieved at the same time using the enumerate() function.

  >>> for i, v in enumerate(['tic', 'tac', 'toe']):
  ...     print i, v
  ...
  0 tic
  1 tac
  2 toe