Functools Reduce

Acronym
Acronym in Python 
from functools import reduce


def abbreviate(to_abbreviate):
    phrase = to_abbreviate.replace("_", " ").replace("-", " ").upper().split()
    
    return reduce(lambda start, word: start + word[0], phrase, "")
  • This approach begins by using str.replace() to "scrub" (remove) non-letter characters such as ',-,_, and white space from to_abbreviate.
  • The phrase is then upper-cased by calling str.upper(),
  • Finally, the phrase is turned into a list of words by calling str.split().

The three methods above are all chained together, with the output of one method serving as the input to the next method in the "chain". This works because both replace() and upper() return strings, and both upper() and split() take strings as arguments. However, if split() were called first, replace() and upper() would fail, since neither method will take a list as input.

Note

re.findall() or re.finditer() can also be used to "scrub" to_abbreviate. These two methods from the re module will return a list or a lazy iterator of results, respectively. As of this writing, both of these methods benchmark slower than using str.replace() for scrubbing.

Once the phrase is scrubbed and turned into a word list, the acronym is created via reduce(). reduce() is a method from the functools module, which provides support for higher-order functions and functional programming in Python.

functools.reduce() applies an anonymous two-argument function (the lambda in the code example) to the items of an iterable. The application of the function travels from left to right, so that the iterable becomes a single value (it is "reduced" to a single value).

Using code from the example above, reduce(lambda start, word: start + word[0], ['GNU', 'IMAGE', 'MANIPULATION', 'PROGRAM']) would calculate ((('GNU'[0] + 'IMAGE'[0])+'MANIPULATION'[0])+'PROGRAM'[0]), or GIMP. The left argument, start, is the accumulated value and the right argument, word, is the value from the iterable that is used to update the accumulated 'total'. The optional 'initializer' value '' is used here, and is placed ahead/before the items of the iterable in the calculation, and serves as a default if the iterable that is passed is empty.

Since using reduce() is fairly succinct, it is put directly on the return line to produce the acronym rather than assigning and returning an intermediate variable.

In benchmarks, this solution performed about as well as both the loops and the list-comprehension solutions.

4th Dec 2024 · Found it useful?

Other Approaches to Acronym in Python

Other ways our community solved this exercise
def abbreviate(to_abbreviate):
    phrase = to_abbreviate.replace('-', ' ').replace('_', ' ').upper().split()

    # note the lack of square brackets around the comprehension.
    return ''.join(word[0] for word in phrase)
Generator Expression

Use a generator expression with str.join() to form an acronym from text cleaned using str.replace(). 

def abbreviate(to_abbreviate):
    phrase = to_abbreviate.replace('-', ' ').replace('_', ' ').upper().split()

    return ''.join([word[0] for word in phrase])
List Comprehension

Use a list comprehension with str.join() to form an acronym from text cleaned using str.replace(). 

def abbreviate(to_abbreviate):
    phrase = to_abbreviate.replace('-', ' ').replace('_', ' ').upper().split()
    acronym = ''

    for word in phrase:
        acronym += word[0]

    return acronym
Loop

Use str.replace() to clean the input string and a loop with string concatenation to form the acronym. 

def abbreviate(to_abbreviate):
    phrase = to_abbreviate.replace("_", " ").replace("-", " ").upper().split()
    
    return ''.join(map(lambda word: word[0], phrase))
Map Built-in

Use the built-in map() function to form an acronym after cleaning the input string with str.replace(). 

import re

def abbreviate(phrase):
    removed = re.findall(r"[a-zA-Z']+", phrase)

    return ''.join(word[0] for word in removed).upper()
Regex join

Use regex to clean the input string and form the acronym with str.join(). 

import re

def abbreviate_regex_sub(to_abbreviate):
    pattern = re.compile(r"(?<!_)\B[\w']+|[ ,\-_]")

    return  re.sub(pattern, "", to_abbreviate.upper())
Regex Sub

Use re.sub() to clean the input string and create the acronym in one step.