Python tutorial- Dictionary


Dictionary


A dictionary or a hash table stores pairs of values and keys. You can access an item of a dictionary through its key.
>>> Dic={'1':'Cambodia','2':'China','3':'USA'}
>>> Dic['1']


'Cambodia'
>>> 
 
You also can create a dictionary from a sequence of pair items or from other dictionaries by using dict() method.
>>> lst=[(1,'Pizza'),(2,'Cheese'),(3,'Fried Chicken')]
>>> Dic1=dict(lst)
>>> Dic1[1]
'Pizza'
>>> 

Dictionary: get, items, keys, values, pop, update, and clear methods:
 
To access the value of an item of a dictionary, you can use get() method:
>>> Dic1.get(1)
'Pizza'
>>> Dic1.get(4)
>>> 
The items() method can return all items of the dictionary in the form (key,value):
>>> Dic1.items()
[(1, 'Pizza'), (2, 'Cheese'), (3, 'Fried Chicken')]
>>> 
To access all keys contained in a dictionary, use keys() method, and to access all values, use values() method:
>>> Dic1.keys()
[1, 2, 3]
>>> Dic1.values()
['Pizza', 'Cheese', 'Fried Chicken']
>>> 
 
You can remove all items of a dictionary by using clear() method:
Like the case of sequence, you can use pop() method to remove an item from a dictionary. However, the pop() method of a dictionary is naturally created to remove an item at whatever position, not just the last one.
>>> Dic1.pop(1)
'Pizza'
>>> Dic1
{2: 'Cheese', 3: 'Fried Chicken'}
>>> 

You can also update a value of item of a dictionary by using update method:
>>> x={1:'Pizza'}
>>> Dic1.update(x)
>>> Dic1
{1: 'Pizza', 2: 'Cheese', 3: 'Fried Chicken'}
>>> y={2:'Hamburger'}
>>> Dic1.update(y)
>>> Dic1
{1: 'Pizza', 2: 'Hamburger', 3: 'Fried Chicken'}
>>> 
To remove all items of the dictionary, you can use clear() method:
>>> Dic1.clear()
>>> Dic1
{}
>>> 




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