Python Dictionaries and collections

Dictionary

Creation of dictionaries

>>> A = {' One': 1,' Both': 2,'three': 3}>>> B = dict (one=1, two=2, three=3)>>> C = Dict ([(' Both', 2), (' One', 1), ('three', 3)])>>> A = = b = =ctrue>>> d = {}.fromkeys ('x','y'), 1)>>>d{'y': 1,'x': 1}

Accessing values in a dictionary

d[key]d.get (Key) D.items (), D.keys (), D.values () D.iteritems (), D.iterkeys (), d.itervalues () ' x ' inch dtrue

Update dictionary

>>> d['x'] = 2#Update>>> d['Z'] = 2#Insert>>> D2 = Dict (one=1, two=2)>>> d3 = Dict (one=10, ten=100)>>>D2.update (D3)>>>d2{' Both': 2,'Ten': 100,' One': 10}

Delete a dictionary element

del d[key]d.pop (key[, default]) D.clear ()

Copy Dictionary

D.copy ()   #  Note is a shallow copy

Collection

A collection (sets) has two different types, a mutable set (set), and an immutable set (Frozenset).
For mutable collections (set), you can add and remove elements, which are not allowed for immutable collections (Frozenset).

Create a Collection

 >>> t = Set ( " hello  "   >>> Tset ([ "  h  , "   ,    L  ,    o  ]) #   >>> set ([1, 2, 3, 4, 1, 2 1, 2, 3, 4])  

Accessing values in a collection

' H ' inch ttrue  for inch T:         Print I

Operation of the collection

A = T | The intersection of S          #  T and S-B = t & S # T and s, C =              t–s #              Differential set (item in T, but not in s)  d = t ^ s          #  symmetric difference set (items in t or S, but not both)

Update Collection

>>> T.add ('m')>>>Tset (['H','m','e','L','o'])>>> T.update (' World')>>>Tset (['e','D','H','m','L','o','R','W'])>>> T.remove ('m')>>>Tset (['e','D','H','L','o','R','W'])>>> T-= set (' World')>>>Tset (['e','H'])

PS: The collection can be used to list the weight

 for  in Set ([11,22,33,44,11,22]) [33, 11, 44, 22]  

2015-05-26

Python Dictionaries and collections