Python - Find Keys with Specific Suffix in Dictionary

Finding keys with a specific suffix in a dictionary is a common task when filtering data based on key patterns. Python provides several approaches to accomplish this using built-in functions like endswith(), filter(), and comprehensions.

Let's consider this dictionary example

my_dict = {'compiler': 100, 'interpreter': 200, 'cooperative': 300, 'cloudbox': 400}
suffix = 'er'
print("Original dictionary:", my_dict)
print("Looking for keys ending with:", suffix)

Original dictionary: {'compiler': 100, 'interpreter': 200, 'cooperative': 300, 'cloudbox': 400}
Looking for keys ending with: er

Key Methods Used

endswith() Returns True if the string ends with the specified suffix

filter() Filters items based on a condition

lambda Creates anonymous functions for short operations

Using List Comprehension

List comprehension provides a concise way to filter keys that end with a specific suffix ?

def find_keys_with_suffix(dictionary, suffix):
    return [key for key in dictionary if key.endswith(suffix)]

# Example dictionary
my_dict = {"dropbox": 1, "box": 2, "chat": 3, "mail": 4}
suffix = "ox"

# Find keys with suffix
result = find_keys_with_suffix(my_dict, suffix)
print(f"Keys with suffix '{suffix}': {result}")

Keys with suffix 'ox': ['dropbox', 'box']

Using filter() Function

The filter() function with lambda provides a functional programming approach ?

def find_keys_with_suffix(dictionary, suffix):
    return list(filter(lambda key: key.endswith(suffix), dictionary))

# Example dictionary
my_dict = {"Evergreen": 1, "Beautiful": 2, "Fruitful": 3, "Golden": 4}
suffix = "ful"

# Find keys with suffix
result = find_keys_with_suffix(my_dict, suffix)
print(f"Keys with suffix '{suffix}': {result}")

Keys with suffix 'ful': ['Beautiful', 'Fruitful']

Using Loop and Conditional Statements

A traditional approach using loops offers more control over the filtering process ?

def find_keys_with_suffix(dictionary, suffix):
    keys_with_suffix = []
    
    for key in dictionary:
        if key.endswith(suffix):
            keys_with_suffix.append(key)
    
    return keys_with_suffix

# Example dictionary
my_dict = {"apple": 1, "banana": 2, "cherry": 3, "orange": 4}
suffix = "y"

# Find keys with suffix
result = find_keys_with_suffix(my_dict, suffix)
print(f"Keys with suffix '{suffix}': {result}")

Keys with suffix 'y': ['cherry']

Using Dictionary Comprehension

Dictionary comprehension maintains both keys and values in the result ?

def find_items_with_suffix(dictionary, suffix):
    return {key: value for key, value in dictionary.items() if key.endswith(suffix)}

# Example dictionary
my_dict = {"programs": 1, "algorithms": 2, "functions": 3, "variables": 4}
suffix = "ms"

# Find key-value pairs with suffix
result = find_items_with_suffix(my_dict, suffix)
print(f"Items with keys ending in '{suffix}': {result}")

Items with keys ending in 'ms': {'programs': 1, 'algorithms': 2}

Comparison

Conclusion

Use list comprehension for simple key filtering with readable syntax. Choose dictionary comprehension when you need to preserve key-value pairs. The filter() method works well for functional programming approaches.