Learning Dictionary in Python

#!/usr/local/bin/python2.7

'''
#Learning Dictionary in Python
    File name: dict_all_operations.py
    Author: Prabhath Kota
    Date: June 22, 2018
    Python Version: 2.7
'''

'''
Python Dictionaries has key value pairs
They are not ordered
They don't have any index
Keys are unique
A key can be any type of objects, for example, a number, string in Python dictionary
Values can be accessed by using key rather than the index 
We can fetch the values by using key
Case sensitive

[ 'clear', 'copy', 'fromkeys', 'get', 'has_key', 'items', 'iteritems', 'iterkeys', 'itervalues', 'keys', 'pop', 'popitem', 'setdefault', 'update', 'values', 'viewitems', 'viewkeys', 'viewvalues']
'''
from copy import deepcopy
import operator

employees = {1000: {'name': 'Sahasra','country': 'India', 'age': 25}, \
1001: {'name': 'Peter','country': 'US', 'age': 21}, \
1002: {'name': 'John','country': 'US', 'age': 36}, \
1003: {'name': 'Sarayu','country': 'India', 'age': 30},\
1004: {'name': 'Akio','country': 'Japan', 'age': 60}, \
1005: {'name': 'Anand','country': 'India', 'age': 50}, \
1006: {'name': 'Vidya','country': 'India', 'age': 32}, \
1007: {'name': 'Salma','country': 'Bangladesh', 'age': 23},}
print employees

#{1000: {'country': 'India', 'age': 25, 'name': 'Sahasra'}, 1001: {'country': 'US', 'age': 21, 'name': 'Peter'}, 1002: {'country': 'US', 'age': 36, 'name': 'John'}, 1003: {'country': 'India', 'age': 30, 'name': 'Sarayu'}, 1004: {'country': 'Japan', 'age': 60, 'name': 'Akio'}, 1005: {'country': 'India', 'age': 50, 'name': 'Anand'}, 1006: {'country': 'India', 'age': 32, 'name': 'Vidya'}, 1007: {'country': 'Bangladesh', 'age': 23, 'name': 'Salma'}}

print '---------------Dictionary Keys---------------'
print employees.keys() #Get employee Ids
#[1000, 1001, 1002, 1003, 1004, 1005, 1006, 1007]

print '---------------Dictionary Values---------------'
print employees.values()
#[{'country': 'India', 'age': 25, 'name': 'Sahasra'}, {'country': 'US', 'age': 21, 'name': 'Peter'}, {'country': 'US', 'age': 36, 'name': 'John'}, {'country': 'India', 'age': 30, 'name': 'Sarayu'}, {'country': 'Japan', 'age': 60, 'name': 'Akio'}, {'country': 'India', 'age': 50, 'name': 'Anand'}, {'country': 'India', 'age': 32, 'name': 'Vidya'}, {'country': 'Bangladesh', 'age': 23, 'name': 'Salma'}]

print '---------------Dictionary Access---------------'
print employees[1002]
#{'country': 'US', 'age': 36, 'name': 'John'}
employee_obj = employees[1002]
print employee_obj['name']
#John
print employee_obj['country']
#US
print employee_obj['age']
#36
#print employee_obj['salary'] #This will throw error
print employee_obj.get('salary') #Get will return None atleast, but won't throw any error

print '---------------Dictionary Check if key exists---------------'
print 1002 in employees
#True
print 2002 in employees.keys()
#False
print employees.has_key('dept')
#None

print '---------------Dictionary Add/update---------------'
print employees
employees[1008] = {'name': 'Sriya','country': 'India', 'age': 42}

print employees.keys()
#[1008, 1000, 1001, 1002, 1003, 1004, 1005, 1006, 1007]

employees.update({1009: {'name': 'Ahmad','country': 'Bangladesh', 'age': 60}})
print employees.keys()
#[1008, 1009, 1000, 1001, 1002, 1003, 1004, 1005, 1006, 1007]

print '---------------Dictionary Delete entry---------------'
print employees.keys()
#[1008, 1009, 1000, 1001, 1002, 1003, 1004, 1005, 1006, 1007]

del employees[1009]

print employees.keys()
#[1008, 1000, 1001, 1002, 1003, 1004, 1005, 1006, 1007]

print employees[1002]
#{'country': 'US', 'age': 36, 'name': 'John'}

del employees[1002]['age']

print employees[1002]
#{'country': 'US', 'name': 'John'}

print employees[1002].pop('country') #You need to specify key name
#US

print employees[1002]
#{'name': 'John'}

print '---'
print employees[1002].popitem() #It randomly removed any one key
#('name', 'John')

print '---'
print employees[1002]
#{}

print '---'
print len(employees)
#9
del employees[1002]

print len(employees)
#8

print '---------------Dictionary copy by ref---------------'
print employees[1008]['age']
employees_1 = employees
employees[1008]['age'] = 45
print employees[1008]['age']
print employees_1[1008]['age']
#42
#45
#45

print '---------------Dictionary shallow copy---------------'
print employees[1008]['age']
employees_1 = employees.copy()
employees[1008]['age'] = 50
print employees[1008]['age']
print employees_1[1008]['age']
#45
#50
#50

print '---------------Dictionary deep copy---------------'
print employees[1008]['age']
employees_1 = deepcopy(employees)
employees[1008]['age'] = 55
print employees[1008]['age']
print employees_1[1008]['age']
#50
#55
#50

print '---------------Dictionary loop---------------'
for key,val in employees.items():
    print key, ' ----> ', val
for key in employees:
    print key, ' ----> ', employees[key]

#1008  ---->  {'country': 'India', 'age': 55, 'name': 'Sriya'}
#1000  ---->  {'country': 'India', 'age': 25, 'name': 'Sahasra'}
#1001  ---->  {'country': 'US', 'age': 21, 'name': 'Peter'}
#1003  ---->  {'country': 'India', 'age': 30, 'name': 'Sarayu'}
#1004  ---->  {'country': 'Japan', 'age': 60, 'name': 'Akio'}
#1005  ---->  {'country': 'India', 'age': 50, 'name': 'Anand'}
#1006  ---->  {'country': 'India', 'age': 32, 'name': 'Vidya'}
#1007  ---->  {'country': 'Bangladesh', 'age': 23, 'name': 'Salma'}


print '---------------Dictionary sort by key---------------'
for key in sorted(employees):
    print key, ' ----> ', employees[key]

#1000  ---->  {'country': 'India', 'age': 25, 'name': 'Sahasra'}
#1001  ---->  {'country': 'US', 'age': 21, 'name': 'Peter'}
#1003  ---->  {'country': 'India', 'age': 30, 'name': 'Sarayu'}
#1004  ---->  {'country': 'Japan', 'age': 60, 'name': 'Akio'}
#1005  ---->  {'country': 'India', 'age': 50, 'name': 'Anand'}
#1006  ---->  {'country': 'India', 'age': 32, 'name': 'Vidya'}
#1007  ---->  {'country': 'Bangladesh', 'age': 23, 'name': 'Salma'}
#1008  ---->  {'country': 'India', 'age': 55, 'name': 'Sriya'}

print '---------------Dictionary sort by value ---------------'
try:
   #Dictionary of Dictionaries - sort of specific value    
   print sorted(employees.items(), key=lambda(x,y): y['age'])
   #[(1001, {'country': 'US', 'age': 21, 'name': 'Peter'}), (1007, {'country': 'Bangladesh', 'age': 23, 'name': 'Salma'}), (1000, {'country': 'India', 'age': 25, 'name': 'Sahasra'}), (1003, {'country': 'India', 'age': 30, 'name': 'Sarayu'}), (1006, {'country': 'India', 'age': 32, 'name': 'Vidya'}), (1005, {'country': 'India', 'age': 50, 'name': 'Anand'}), (1008, {'country': 'India', 'age': 55, 'name': 'Sriya'}), (1004, {'country': 'Japan', 'age': 60, 'name': 'Akio'})]

   #Based on Value
   x = {1: 2000, 3: 8000, 4: 2500, 2: 9000, 9:10000, 7:9500}
   print x
   #{1: 2000, 2: 9000, 3: 8000, 4: 2500, 7: 9500, 9: 10000}

   sorted_x = sorted(x.items(), key=operator.itemgetter(1))
   print sorted_x
   #[(1, 2000), (4, 2500), (3, 8000), (2, 9000), (7, 9500), (9, 10000)]

   sorted_x = sorted(x.items(), key=lambda(x,y): y)
   print sorted_x
   #[(1, 2000), (4, 2500), (3, 8000), (2, 9000), (7, 9500), (9, 10000)]
except Exception, e:
   print e