[Tutor] Dictionary Nesting

[Kent Johnson]

jhomme wrote:
> Hi,
> If I want to put a dictionary in a dictionary, does the syntax for assigning and getting at the
> stuff in the inner dictionary look something like this:
> outer_dictionary[inner_dictionary][key] = 'value' > ?

If inner_dictionary is the key to outer_dictionary, then that is right. For example,

Create the outer dict:
  >>> outer = {}

Create an inner dict:
  >>> outer['outerkey'] = {}

Add a key/value pair to the inner dict
  >>> outer['outerkey']['innerkey'] = 'myvalue'
  >>> outer
{'outerkey': {'innerkey': 'myvalue'}}

Retrieve the inner dict:
  >>> outer['outerkey']
{'innerkey': 'myvalue'}

Retrieve an entry from the inner dict:
  >>> outer['outerkey']['innerkey']
'myvalue'

setdefault() is handy here because you may not know if the inner dict has been created yet when you 
want to add an entry. If not, setdefault will do it for you:
  >>> outer.setdefault('outerkey2', {})['innerkey2'] = 'anotherValue'
  >>> outer
{'outerkey2': {'innerkey2': 'anotherValue'}, 'outerkey': {'innerkey': 'myvalue'}}

If the inner dict is there already setdefault will use it:
  >>> outer.setdefault('outerkey2', {})['innerkey3'] = 'yetAnotherValue'
  >>> outer
{'outerkey2': {'innerkey2': 'anotherValue', 'innerkey3': 'yetAnotherValue'}, 'outerkey': 
{'innerkey': 'myvalue'}}

Kent
> 
> Thanks.
> 
> Jim
> 
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