6.2.4 Dictionary Methods keys and values

In [1]:
months = {'January': 1, 'February': 2, 'March': 3}
In [2]:
for month_name in months.keys():
    print(month_name, end='  ')
   

January  February  March
In [3]:
for month_number in months.values():
    print(month_number, end='  ')

1  2  3

Dictionary Views

  • Methods items, keys and values each return a view of a dictionary’s data.
  • When you iterate over a view, it “sees” the dictionary’s current contents—it does not have its own copy of the data.
In [4]:
months_view = months.keys()
In [5]:
for key in months_view:
    print(key, end='  ')
    

January  February  March
In [6]:
months['December'] = 12
In [7]:
months
Out[7]:
{'January': 1, 'February': 2, 'March': 3, 'December': 12}
In [8]:
for key in months_view:
    print(key, end='  ')
    

January  February  March  December

Converting Dictionary Keys, Values and Key–Value Pairs to Lists

In [9]:
list(months.keys())
Out[9]:
['January', 'February', 'March', 'December']
In [10]:
list(months.values())
Out[10]:
[1, 2, 3, 12]
In [11]:
list(months.items())
Out[11]:
[('January', 1), ('February', 2), ('March', 3), ('December', 12)]

Processing Keys in Sorted Order

In [12]:
for month_name in sorted(months.keys()):
     print(month_name, end='  ')

December  February  January  March

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