"Python" 11, Python's Dictionary of built-in data structures

First, the dictionary

1, the initialization of the dictionary

A dictionary is a key-value structure

in [160]: d = {}in [161]: type (d) Out[161]:  dictin [166]: d = {' A ':1,  ' B ': 2}in [167]: dout[167]: {' a ':  1,  ' B ':  2}in [180]: d = dict ({"A":0,  "B": 1}) in [181]: dout[181]:  {' A ': 0,  ' B ':  1}in [164]: d = dict ([["A",  1], ["B",  2] ])    # The elements of an iterative object must be a two-tuple in [165]: dout[165]: {' a ': 1,  ' B ':  2}in  [168]: d = dict.fromkeys (Range (5)) #  The iterated element passed in as key, with a value of nonein [169]: dout[169] :  {0: none, 1: none, 2: none, 3: none, 4: none}in [170] :  d = dict.fromkeys (Range (5),  "ABC")   #  incoming iteration element is key, value is abcin [171]:  dOut[171]: {0:  ' abc ', 1:  ' abc ', 2:  ' abc ', 3:  ' abc ',  4:   ' abc '} 

Second, the basic operation of the dictionary

1, increase

In [173]: D = {' A ': 1, ' B ': 2} # directly using key as an index, assigning a value to a non-existent index increases KV to in [174]: d["c"] = 1In [175]: dout[175]: {' A ': 1, ' B ': 2, ' C ': 1}in [175]: dout[175]: {' A ': 1, ' B ': 2, ' C ': 1}in [176]: d["b"] = 1In [177]: dout[177]: {' A ': 1, ' B ': 1, ' C ': 1}## di Ct.update () in [178]: D.update ((("D", 4), ("E", 5)) in [179]: dout[179]: {' A ': 1, ' B ': 1, ' C ': 1, ' d ': 4, ' E ': 5}

"Python" 11, Python's Dictionary of built-in data structures