Python - Sort Dictionary Key and Values List

Given a dictionary containing keys and corresponding lists as values, the task is to sort both the dictionary keys in ascending order and the lists of values for each key. For Example:

Input: {'c': [3], 'b': [12, 10], 'a': [19, 4]} 
Output: {'a': [4, 19], 'b': [10, 12], 'c': [3]} 

Let's explore different methods to sort dictionary key and values list in Python.

Using Dictionary Comprehension + sorted()

This method combines both key sorting and value list sorting in a single line using dictionary comprehension.

t = {'gfg': [7, 6, 3], 'is': [2, 10, 3], 'best': [19, 4]}
res = {key: sorted(t[key]) for key in sorted(t)}
print(res)

{'best': [4, 19], 'gfg': [3, 6, 7], 'is': [2, 3, 10]}

Explanation:

• sorted(t) sorts dictionary keys in ascending order.
• {key: sorted(t[key]) ...} creates a new dictionary with each list of values sorted.

Using Lambda Function with sorted()

This method sorts dictionary items using a lambda function, then sorts the lists of values for each key.

t = {'gfg': [7, 6, 3], 'is': [2, 10, 3], 'best': [19, 4]}
res = dict(sorted(t.items(), key=lambda x: x[0]))

for key in res:
    res[key] = sorted(res[key])
print(res)

{'best': [4, 19], 'gfg': [3, 6, 7], 'is': [2, 3, 10]}

Explanation:

• sorted(t.items(), key=lambda x: x[0]): Sorts items by key.
• dict(...): Converts sorted pairs back to a dictionary.
• res[key] = sorted(res[key]): Sorts each value list.

Using zip() with sorted()

This method zips dictionary keys and values into tuples, sorts them by key, and then reconstructs the dictionary.

t = {'gfg': [7, 6, 3], 'is': [2, 10, 3], 'best': [19, 4]}
keys = list(t.keys())
values = list(t.values())

s1 = sorted(zip(keys, values), key=lambda x: x[0])
res = {k: sorted(v) for k, v in s1}

print(res)

{'best': [4, 19], 'gfg': [3, 6, 7], 'is': [2, 3, 10]}

Explanation:

• zip(keys, values): Pairs each key with its list.
• sorted(..., key=lambda x: x[0]): Sorts key-value pairs by key.
• {k: sorted(v) for k, v in s1}: Rebuilds a sorted dictionary.

Using Recursive Method

This approach recursively finds and sorts the smallest key and its corresponding list, then processes the remaining dictionary.

def sort_dict(t):
    if not t:
        return {}
    m1 = min(t.keys())
    s1 = sorted(t[m1])
    remaining = {k: v for k, v in t.items() if k != m1}
    return {m1: s1, **sort_dict(remaining)}

t = {'gfg': [7, 6, 3], 'is': [2, 10, 3], 'best': [19, 4]}
res = sort_dict(t)
print(res)

{'best': [4, 19], 'gfg': [3, 6, 7], 'is': [2, 3, 10]}

Explanation:

• min(t.keys()): Finds the smallest key.
• sorted(t[m1]): Sorts the value list for that key.
• Recursively sorts remaining keys until the dictionary is empty.

Related Articles:

• How to Sort a Dictionary by Value
• Sort List by Dictionary values