Dictionaries

In [25]:

    

# create an empty dictionary
d = dict()
# or
d = {}


    

In [26]:

    

bob1 = dict(name='Bob', job='dev', age=40)
print bob1


    

    




{'age': 40, 'job': 'dev', 'name': 'Bob'}

In [27]:

    

bob2 = dict(zip(['name', 'job', 'age'], ['Bob', 'dev', 40]))
print bob2


    

    




{'age': 40, 'job': 'dev', 'name': 'Bob'}

In [31]:

    

bob2['name'] = 'jimmy'


    

In [32]:

    

bob2['name']


    

    
Out[32]:





'jimmy'

In [33]:

    

bob1['name']


    

    
Out[33]:





'Bob'

In [29]:

    

# create a dictionary
d = {'Name': 'Jimmy', 
     "phone": '850-882-0340', 
     "Work": "Eglin AFB",
     1:3}
d


    

    
Out[29]:





{1: 3, 'Name': 'Jimmy', 'Work': 'Eglin AFB', 'phone': '850-882-0340'}

In [81]:

    

# get the value of 'Name'
d['Name']


    

    
Out[81]:





'Jimmy'

In [45]:

    

# dictionary keys are case sensitive
d['name']


    

    




---------------------------------------------------------------------------
KeyError                                  Traceback (most recent call last)
<ipython-input-45-5af8309a2bc6> in <module>()
      1 # dictionary keys are case sensitive
----> 2 d['name']

KeyError: 'name'

In [83]:

    

# get value of a key. it not present give back message
d.get('name', 'no such key')


    

    
Out[83]:





'no such key'

In [46]:

    

# change a value
d['Name'] = 'James'
d


    

    
Out[46]:





{1: 3, 'Name': 'James', 'Work': 'Eglin AFB', 'phone': '850-882-0340'}

In [47]:

    

# add a key-value
d['school'] = 'Aubun'
d


    

    
Out[47]:





{1: 3,
 'Name': 'James',
 'Work': 'Eglin AFB',
 'phone': '850-882-0340',
 'school': 'Aubun'}

In [48]:

    

# rm a key-value
del d['school']
d


    

    
Out[48]:





{1: 3, 'Name': 'James', 'Work': 'Eglin AFB', 'phone': '850-882-0340'}

In [49]:

    

# change it to a string
str(d)


    

    
Out[49]:





"{'phone': '850-882-0340', 'Work': 'Eglin AFB', 'Name': 'James', 1: 3}"

In [50]:

    

# get its length
len(d)


    

    
Out[50]:





4

In [51]:

    

# clear dictionary but don't delete it
d.clear()
d


    

    
Out[51]:





{}

In [52]:

    

# create a dictionary
d = {'Name': 'Jimmy', 
     "phone": '850-882-0340', 
     "Work": "Eglin AFB"}


    

In [53]:

    

# check for key
d.has_key('name')


    

    
Out[53]:





False

In [54]:

    

# get the items of a dictionary
d.items()


    

    
Out[54]:





[('phone', '850-882-0340'), ('Work', 'Eglin AFB'), ('Name', 'Jimmy')]

In [55]:

    

# just get the keys
d.keys()


    

    
Out[55]:





['phone', 'Work', 'Name']

In [56]:

    

# just get the values
d.values()


    

    
Out[56]:





['850-882-0340', 'Eglin AFB', 'Jimmy']

In [57]:

    

# print both the keys and values
for k,v in d.items():
    print k,v


    

    




phone 850-882-0340
Work Eglin AFB
Name Jimmy

In [58]:

    

# copy a dictionay
dd = d
print dd is d
print d,dd


    

    




True
{'phone': '850-882-0340', 'Work': 'Eglin AFB', 'Name': 'Jimmy'} {'phone': '850-882-0340', 'Work': 'Eglin AFB', 'Name': 'Jimmy'}

In [59]:

    

dd['Name']='Alex'


    

In [126]:

    

d,dd


    

    
Out[126]:





({'Name': 'Alex', 'Work': 'Eglin AFB', 'phone': '850-882-0340'},
 {'Name': 'Alex', 'Work': 'Eglin AFB', 'phone': '850-882-0340'})

In [60]:

    

# change a value
d['Name'] = 'JT'
d,dd


    

    
Out[60]:





({'Name': 'JT', 'Work': 'Eglin AFB', 'phone': '850-882-0340'},
 {'Name': 'JT', 'Work': 'Eglin AFB', 'phone': '850-882-0340'})

In [128]:

    

dd is d


    

    
Out[128]:





True

In [61]:

    

# another way to copy dictionaries
dd = d.copy()
print dd is d
print d,dd


    

    




False
{'phone': '850-882-0340', 'Work': 'Eglin AFB', 'Name': 'JT'} {'phone': '850-882-0340', 'Work': 'Eglin AFB', 'Name': 'JT'}

In [62]:

    

# change a value
dd['Name']='Alex'
d,dd


    

    
Out[62]:





({'Name': 'JT', 'Work': 'Eglin AFB', 'phone': '850-882-0340'},
 {'Name': 'Alex', 'Work': 'Eglin AFB', 'phone': '850-882-0340'})

In [63]:

    

d['Name'] = 'JT'
d,dd


    

    
Out[63]:





({'Name': 'JT', 'Work': 'Eglin AFB', 'phone': '850-882-0340'},
 {'Name': 'Alex', 'Work': 'Eglin AFB', 'phone': '850-882-0340'})

In [34]:

    

# nesting - no restrictions on value
rec = {'name': {'first': ['bob', 'mob'], 'last': 'Smith'},
           'jobs': ['dev', 'mgr'],
           'age':  40.5}
print rec


    

    




{'age': 40.5, 'jobs': ['dev', 'mgr'], 'name': {'last': 'Smith', 'first': ['bob', 'mob']}}

In [35]:

    

rec.keys()


    

    
Out[35]:





['age', 'jobs', 'name']

In [36]:

    

rec.values()


    

    
Out[36]:





[40.5, ['dev', 'mgr'], {'first': ['bob', 'mob'], 'last': 'Smith'}]

In [37]:

    

# access the first element
rec['name']


    

    
Out[37]:





{'first': ['bob', 'mob'], 'last': 'Smith'}

In [38]:

    

rec['name']['first']


    

    
Out[38]:





['bob', 'mob']

In [40]:

    

rec['name']['first'][1]


    

    
Out[40]:





'mob'