Dictionaries

A dictionary consists of (key,value) pairs
The key is an immutable type(e.g. a number, a string, a tuple)
The value can be anything
We retrieve the value in a dictionary by using the associated key
Dictionaries are fancy lists that are not restricted to consecutive integers for indexing
We create dictionaries with curly braces { }
We assign elements to and retrieve elements from dictionaries with square brackets [key]
In [1]: emails={}
In [2]: emails['Duan']='[email protected]'
In [3]: emails['Charlie']='[email protected]'
In [4]: emails['Stuart']='[email protected]'
In [5]: emails['Allen']='[email protected]'
In [6]: emails.keys()
Out[6]: ['Allen', 'Charlie', 'Duan', 'Stuart']
In [7]: emails.values()
Out[7]: ['[email protected]', '[email protected]', '[email protected]', '[email protected]']
In [8]: emails
Out[8]:
{'Charlie': '[email protected]',
'Duan': '[email protected]',
'Allen': '[email protected]',
'Stuart': '[email protected]'}
In [9]: emails['Duan']
Out[9]: '[email protected]'
Dictionaries can be constructed from a list of (key,value) pairs (or 2-turples)from two matching lists or keys and values
In [10]: instructors=['Duan','Charlie','Stuart','Allen']
In [11]: email=['[email protected]','[email protected]','[email protected]','[email protected]']
In [12]: adict=dict(zip(instructors,email))
In [13]: adict
Out[14]:
{'Charlie': '[email protected]',
'Duan': '[email protected]',
'Allen': '[email protected]',
'Stuart': '[email protected]'}
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