In [1]:

    

dict = {'key':'a', 'key1':'2', 'key2':'2.34'}


    

In [2]:

    

dict


    

    
Out[2]:





{'key': 'a', 'key1': '2', 'key2': '2.34'}

In [4]:

    

dict['key1']


    

    
Out[4]:





'2'

In [5]:

    

#good exmaple of dictionary usecase would be items in a store.
items = {'apples':1.76, 'bananas':1.00, 'toy car':2.99}


    

In [23]:

    

car = str(items['toy car']) #to call an integer as a string this must be cast inside parenthises.


    

In [24]:

    

car


    

    
Out[24]:





'2.99'

In [25]:

    

print('The cost of this item is: $' + car) # Alas after several attempts, this now prints out nicely.


    

    




The cost of this item is: $2.99

In [32]:

    

out = 'some string $'


    

In [33]:

    

car = items['toy car']


    

In [34]:

    

out + car # See the difference.


    

    




---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-34-3962787f3896> in <module>()
----> 1 out + car # See the difference.

TypeError: must be str, not float

In [35]:

    

print(out + str(car)) # Integers or float datatypes have to be cast to string.


    

    




some string $2.99

In [40]:

    

dtypes = {'k1':23, 'k2':[1, 2, 3], 'k3':{'key':'value1', 'key1':23.4, 'key2':['a', 'b', 'c']}}
#Examples of nesting and multiple datatypes including nesting lists within dictionaries and dictionaries inside dictionaries.


    

In [44]:

    

dtypes['k3']


    

    
Out[44]:





{'key': 'value1', 'key1': 23.4, 'key2': ['a', 'b', 'c']}

In [45]:

    

d = dtypes['k3']


    

In [46]:

    

d


    

    
Out[46]:





{'key': 'value1', 'key1': 23.4, 'key2': ['a', 'b', 'c']}

In [49]:

    

list = d['key2']


    

In [50]:

    

list


    

    
Out[50]:





['a', 'b', 'c']

In [51]:

    

list[1]


    

    
Out[51]:





'b'

In [53]:

    

dtypes


    

    
Out[53]:





{'k1': 23,
 'k2': [1, 2, 3],
 'k3': {'key': 'value1', 'key1': 23.4, 'key2': ['a', 'b', 'c']}}

In [54]:

    

# The proper syntax to call nested values is as follows
dtypes['k3']['key2'][1]


    

    
Out[54]:





'b'

In [55]:

    

# Can then add methods for example:
dtypes['k3']['key2'][1].upper()


    

    
Out[55]:





'B'

In [56]:

    

nd = {'k1':100, 'k2':200}


    

In [57]:

    

nd


    

    
Out[57]:





{'k1': 100, 'k2': 200}

In [59]:

    

nd.append('k3':300) # Bad, very bad.


    

    




  File "<ipython-input-59-8870947e74f8>", line 1
    nd.append('k3':300) # Bad, very bad.
                  ^
SyntaxError: invalid syntax

In [60]:

    

nd['k3'] = 300


    

In [61]:

    

nd


    

    
Out[61]:





{'k1': 100, 'k2': 200, 'k3': 300}

In [63]:

    

nd.keys()


    

    
Out[63]:





dict_keys(['k1', 'k2', 'k3'])

In [64]:

    

nd.items()


    

    
Out[64]:





dict_items([('k1', 100), ('k2', 200), ('k3', 300)])

In [67]:

    

nd.fromkeys('k2')


    

    
Out[67]:





{'2': None, 'k': None}

In [69]:

    

nd.fromkeys('200')


    

    
Out[69]:





{'0': None, '2': None}

In [70]:

    

nd.values()


    

    
Out[70]:





dict_values([100, 200, 300])

In [71]:

    

nd.get('k3')


    

    
Out[71]:





300

In [ ]:

    




    

In [ ]: