#DICTIONARY
#It is a collection which is unordered, changeable and indexed which doesn't allow duplicate members.

#Dictionary holds key:value pair. 
student= {'name' : 'kushagra', 'age' : 23, 'interests' : [ 'Maths' ,'Science']}

print(student)

{'name': 'kushagra', 'age': 23, 'interests': ['Maths', 'Science']}

#accessing value of dictionary
print(student['interests'])

['Maths', 'Science']

#gives an KeyError if key:value doesn't exist
print(student['hobby'])

---------------------------------------------------------------------------
KeyError                                  Traceback (most recent call last)
<ipython-input-5-6c738bc2be74> in <module>
      1 #gives an error if key:value doesn't exist
----> 2 print(student['hobby'])

KeyError: 'hobby'

#using get function which doesnot give error when data not available
print(student.get('phone'))

None

#you can also set the return value in case data is not available
print(student.get('name','Not Found'))
print(student.get('phone','Not Found'))

kushagra
Not Found

#Adding and Appending Elements to Dict
student['phone']='555-55555'
student['name']='jane'

print(student)

{'name': 'jane', 'age': 23, 'interests': ['Maths', 'Science'], 'phone': '555-55555'}

#using update multiple changes at once
student.update({'name': 'yo' , 'age' : 26 , 'phone' : '99-99999'})
print(student)

{'name': 'yo', 'age': 26, 'interests': ['Maths', 'Science'], 'phone': '99-99999'}

#Deleting Element
del student['age']
print(student)

{'name': 'yo', 'interests': ['Maths', 'Science'], 'phone': '99-99999'}

#removes the value of given key and stores in the variable
no=student.pop('phone')
print(student)

{'name': 'yo', 'interests': ['Maths', 'Science']}

print(no)

99-99999

#printing keys of dict
print(student.keys())

dict_keys(['name', 'interests'])

#printing values of dict
print(student.values())

dict_values(['yo', ['Maths', 'Science']])

#printing items of dict
print(student.items())

dict_items([('name', 'yo'), ('interests', ['Maths', 'Science'])])

#Iterating over dictionary.
for key, value in student.items():
    print(key, value)

name yo
interests ['Maths', 'Science']