Dictionary In Python

                                     Dictionary In Python

Dictionary is nothing but a collection of key-value pair . In python  Dictionary is an unordered collection of data values, used to store data values like a map, which holds key:value pair.Each key-value pair in a Dictionary is separated by a colon :, whereas each key is separated by a ‘comma’. The working concept of Dictionary in python is similar to that of real world dictionary.Keys are unique within a dictionary while values may not be.

Creating a Dictionary:

• An empty dictionary without any items is written with just two curly braces, like this: {}. 

          Example -:  nameage  = {} 

• The key of a dictionary can be of any data type, but values may be repeated.

           Example-:  nameage = {'Name': 'George', 'Age':37}

Updating Dictionary 

• We can update a dictionary by adding a new key-pair into it or by modifying existing value.
  
   Example-:    nameage['Age'] = 8
                     nameage['Country'] = 'Australia'                                                                                   
• We can update the value of different data types.
• We should add new key-value pair in sequential order that is , if we are updating a value and try to add a new key-value at same time, then first we should update the already defined key value of that dictionary after that we can add new key-value pair.

Delete Dictionary Elements

• We can delete single element(key-value pair) or can clear entire dictionary .
• We can also delete entire dictionary .  

          Example -:   del nameage['Name']    => It will delete all value with "Name" key.
                             nameage.clear()           =>  It will clear entire dictionary.
                             del nameage                =>  It  will delete dictionary itself.

 Built-in Functions:

1.  cmp(dict1,dict2) : Its compares elements of both the dictionaries.
2.  len(dict) : It counts the total number of elements(key-value pair) in dictionary.
3.  str(dict)  : It converts dictionary into a printable string format.
4.  dict.clear()  : It removes all elements of the dictionary.
5.  dict.copy()  : It copies elements of dictionary into key-value pair. 
6.  dict.keys()   : It returns all the keys of dictionary.
7.  dict.values()  : It returns list of values of dictionary.

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