Dictionnaries

Simple example

In [6]:
instruments = {'Paul': 'Bass', 'John': 'Guitar'}
In [7]:
instruments['George'] = 'Guitar'
instruments
Out[7]:
{'Paul': 'Bass', 'John': 'Guitar', 'George': 'Guitar'}

test if a key exists

In [8]:
>>> 'Ringo' in instruments
Out[8]:
False

get all keys

In [18]:
instruments.keys()
Out[18]:
dict_keys(['Paul', 'John', 'George'])

get all values

In [19]:
instruments.values()
Out[19]:
dict_values(['Bass', 'Guitar', 'Guitar'])

get all keys and values

In [20]:
instruments.items()
Out[20]:
dict_items([('Paul', 'Bass'), ('John', 'Guitar'), ('George', 'Guitar')])

iterating over a dict

In [5]:
for name in instruments:
    print('{} - {}'.format(name, instruments[name]))

Paul - Bass
John - Guitar
George - Guitar

Comprehension list

In [16]:
plays_guitar = [ musician for musician, instrument 
                in instruments.items() if instrument == 'Guitar']
In [17]:
plays_guitar
Out[17]:
['John', 'George']

Next

  • tuples
  • sets
  • objects
  • comprehensions
  • lambda functions
  • magic methods etc.
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