Add a dict view usage example.

This commit is contained in:
Georg Brandl 2007-09-04 17:58:02 +00:00
parent 952aea2ce6
commit c53c9666f5
1 changed files with 30 additions and 0 deletions

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@ -1906,6 +1906,36 @@ to another dictionary view or a set):
four operations will fail if an involved dictionary contains such a value.
An example of dictionary view usage::
>>> dishes = {'eggs': 2, 'sausage': 1, 'bacon': 1, 'spam': 500}
>>> keys = dishes.keys()
>>> values = dishes.values()
>>> # iteration
>>> n = 0
>>> for val in values:
... n += val
>>> print(n)
504
>>> # keys and values are iterated over in the same order
>>> list(keys)
['eggs', 'bacon', 'sausage', 'spam']
>>> list(values)
[2, 1, 1, 500]
>>> # view objects are dynamic and reflect dict changes
>>> del dishes['eggs']
>>> del dishes['sausage']
>>> list(keys)
['spam', 'bacon']
>>> # set operations
>>> keys & {'eggs', 'bacon', 'salad'}
{'eggs', 'bacon'}
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