Python spellcheck function – replace standalone words but not substrings

Scraping thousands of lines of data, I’ve created a spellcheck function for specific terms that are often misspelled, automatically correcting them before writing to file.

This works well if it’s a standalone word like "apple" and I replace it with "orange", but becomes a problem if it’s "pineapple" and turns into "pineorange". As a workaround, I pad the original term with a space on either side, but this causes it to miss out on occurrences where characters like a period are after it, "apple." for example.

What options do I have to improve the handling here? Preferably something other than a bunch of if checks on the last character.

spelling_dict = {
    "abc" : "ABC",
    "apple" : "Apple",
    "tortose" : "Tortoise"
}

def spellcheck(line):
    for word, correction in spelling_dict.items():
        
        # Pad words with a space on either side
        word = word.center( len(word) + 2 )
        correction = correction.center ( len(correction) + 2 )

        line = line.replace(word, correction)
        
    return line

myphrase = "For apple, I want to capitalize both occurrences of apple."
fixedphrase = spellcheck(myphrase)

print(fixedphrase)

>Solution :

Looks like you want regular expressions. In this case, the pattern (the thing to look for) is the string apple wrapped in word-boundaries \\b:

import re

pattern = "\\bapple\\b"

phrase = "apple pineapple apples and apple."

print(re.sub(pattern, "orange", phrase))

Output:

orange pineapple apples and orange.
>>> 

Notice how apple and apple. were replaced with orange and orange., but pineapple and apples remain unchanged.