The operation of the dictionary in Python Zz__python

Dictionaries

the dictionary in Python, like the HashMap in Java, exists and operates in the form of key-value pairs, which are characterized by access through keys, not offsets; key-value pairs are unordered; keys and values can be arbitrary; length variable, arbitrary nested; In the dictionary, no more sequence operations, although the dictionary is similar to the list in some ways, but do not set the list in the dictionary

 1 Basic Operation python code strong>>>> table = {' abc ':1,  ' def ':2,  ' Ghi ': 3}    >>>  table[' abc ']    1    >>> len (table)    3    >>>  Table.keys ()    [' abc ',  ' Ghi ',  ' def ']    >>> table.values ()     [1, 3, 2]    >>> table.has_key (' def ')    true   > >> table.items ()    [(' abc ',  1),  (' Ghi ',  3),  (' Def ',  2)]   

2) Modify, delete, add python code >>> table = {' abc ': 1, ' Def ': 2, ' Ghi ': 3} >>> t able[' ghi '] = (' g ', ' h ', ' I ') >>> table {' abc ': 1, ' Ghi ': (' g ', ' h ', ' I '), ' Def ': 2} >>> del ta ble[' abc '] >>> table {' Ghi ': (' g ', ' h ', ' I '), ' Def ': 2} >>> table[' xyz '] = [' x ', ' y ', ' Z '] & gt;>> Table {' xyz ': [' x ', ' y ', ' z '], ' ghi ': (' g ', ' h ', ' I '), ' Def ': 2}

here, for the dictionary expansion, just define a new key-value pair, and for the list, you can only use the Append method or fragment assignment.

3) Traversal of the dictionary python code >>> table = {' abc ':1,  ' def ':2,  ' Ghi ': 3}    >>>  for key in table.keys ():        print key,  '/t ',  table[key]               abc     1    ghi     3    def     2