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Python Dictionary

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Python Dictionary

Dictionary overview

Dictionaries are used to store data values in key:value pairs. A dictionary is a collection which is ordered*, changeable and do not allow duplicates. Dictionaries are written with curly brackets, and have keys and values: 

dict = {'Name': 'Zara', 'Age': 7, 'Class': 'First'}
print(dict['Name'])
#print (dict['Age12'])
#print(dict)

Accessing Items

You can access the items of a dictionary by referring to its key name, inside square brackets: There is also a method called get() that will give you the same result: 

dict = {'Name': 'Zara', 'Age': 7, 'Class': 'First'}
print(dict["Name"])
print(dict.get("Name"))

#print (dict['Age12'])
#print(dict)

Dictionary Update Items

Using Below Code snippts shows the Updating Items in dicitionary. 

dict = {'Name': 'Zara', 'Age': 7, 'Class': 'First'}
dict["Age"] = 8

Dictionary Remove item

The del keyword removes the item with the specified key name: 

test_dict = {'Name': 'Zara', 'Age': 7, 'Class': 'First'}
#del test_dict['Name']; # remove entry with key 'Name'
#test_dict.clear();     # remove all entries in dict
#del test_dict ;        # delete entire dictionary
#print(test_dict)

Loop Dictionaries

Loop through both keys and values, by using the items() method: 

test_dict = {1:'aakash',2:'kumar',3:'Bihar',4:'piro'}
#print(test_dict.items())
#print(test_dict.items())
for k, v in test_dict.items():
  print(k," ",v)

Dictionary keys()

Returns a list containing the dictionary’s keys 

ex = {'Name': 'Zara', 'Age': 7}
print(list(ex.keys()))

Dictionary values()

Returns a list of all the values in the dictionary 

ex = {'Name': 'Zara', 'Age': 7}
print(list(ex.values()))

Dictinoary __contains__()

The __contains__() is used to check whether a key exists , if exists it will give true else False 

dict = {'Name': 'Zara', 'Age': 7}
#print (dict.__contains__('Name'))  # __contains__('key')
#print (dict.__contains__('Sex'))

Dictionary len()

len() is use to count the number of key and value pair. 

dict = {'Name': 'Zara', 'Age': 7, 'Class': 'First'}
print(len(dict))
#print (dict['Age12'])
#print(dict)