How Can I Create a Sorted, Ordered Collection from a Python Dictionary?

Sorting a Dictionary by Key: Acquiring an Ordered Collection

The intrinsic nature of Python's dictionaries is unordered, barring the introduction of Python 3.7. While sorting the (key, value) pairs may appear as a solution, it's crucial to acknowledge that preserving the sorted order upon storing the elements back into a dictionary is not feasible.

To seamlessly establish an ordered collection based on key values, the utilization of the OrderedDict class prevails as the optimum approach. This class possesses the unique ability to retain the insertion sequence of its elements:

import collections

d = {2: 3, 1: 89, 4: 5, 3: 0}

# Construct an OrderedDict from sorted key-value pairs
od = collections.OrderedDict(sorted(d.items()))

print(od)  # OrderedDict([(1, 89), (2, 3), (3, 0), (4, 5)])

Although od's printed representation may vary, it will uphold the desired order during subsequent interactions:

print(od[1])  # 89
print(od[3])  # 0

for k, v in od.items():
    print(k, v)  # 1 89, 2 3, 3 0, 4 5

Considerations for Python 3 Users

Python 3 users should employ the .items() method instead of .iteritems() when iterating through the OrderedDict for maintaining compatibility:

for k, v in od.items():
    print(k, v)  # 1 89, 2 3, 3 0, 4 5

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